Introducing RANDALLfoil - 5% speed advantage

[lladn...@gmail.com]

Greetings All,
I would like to introduce my oar design to the Google rowing community called the RANDALLfoil - link https://hydrofoiloar.blogspot.com.au/

It was discovered after considering how to eliminate all contact between the oar shaft and the water during the rowing stroke.

Bio-Mechanical scientist Dr. Kleshnev measured this drag effect or "braking splash" on boat speed and found it to be a significant limiting factor on speed. See BioRow Newsletter No 173 August 2015 Dr. Kleshnev - link http://www.biorow.com/RBN_en_2015_files/2015RowBiomNews08.pdf

The RANDALLfoil is a simple 90-degree strip attached to the top edge of the blade. The design serves as a hydrofoil and restricts the depth that an oar may be buried under the water during the stroke. The design is counter-intuitive and seems to go against the long-held assumption that the deeper the oar is buried the more 'grip' it gets.

The effect of adding a hydrofoil to an oar has been tested independently by Dr.Kleshnev and the Australian Women's National Training Centre with results showing a 3-5% speed increase and a reduction in catch slip. Results have been published on the RANDALLfoil web page. Early adopters in NZ, UK, US and Australia are also replicating results.

FISA has recently ruled that the RANDALLfoil conforms to all current laws and has allowed it to be used in competition, including all World Rowing events.*

There have been many people who have assisted in the development of this design and I would like to thank the following people within the rowing community.
- Dan Noonan, Australian Olympic Medalist
- John Keogh, Head Coach of the Australian Women's Rowing
- Dr. Valery Kleshnev of Bio Row
- Nancy Churchill, Director of Masters Rowing Western Australia
- Magnus Butlin, 2018 NSW State Masters Champion
- Drikus Conradie, NZ International Rower

"Keep your eye's in the boat"
Ian Randall

* The commercialisation of this design was a requirement for FISA certification, however, the primary intention of this project was to share this discovery with the rowing community.

[Mel Harbour]

Interesting stuff, but just a couple of basic criticisms of the maths that you're presenting that you might like to correct (see this page https://hydrofoiloar.blogspot.com/p/documents.html)

1. You quote a table with an increase of boat speed of "upto 4.5%". But in the following table, you observe that there was an increase of power output of "upto 12.8%". But you need to be clear - Biorow doesn't measure power *output*, they measure power *input*, so you haven't demonstrated with those tables that the foil is responsible for a 4.5% speed increase. You've shown that when an athlete pulls harder, they go faster. You need to remove the effect of the different input power in order to make a fair comparison.

2. Later, you ran trials via a number of 1km pieces. You observe a difference in average times with the foil blades recording roughly 0.5 seconds faster. But the variance of the times recorded is much larger than that, so you need to account for that and determine whether the results actually achieve significance. My guess, without having actually run the numbers, is that they aren't achieving mathematical significance - in other words you can't tell whether the foils are better or not.

But good to see attempts at innovation!

Mel

[stan...@gmail.com]

<snipped to avoid repetition>

The Smoothie 1 from concept2 had a similar though less pronounced lip at the top and was VERY depth stable as a result- possibly my favourite set of sculls to date!

Concept2 then replaced it with the smoothie 2
Quote from https://www.concept2.com/oars/oar-options/blades/smoothie2-plain-edge
"The Smoothie had no central ridge (a holdover from wooden blades). The design included a curved “lip” at the top edge that aided in maintaining proper level in the water and was slightly less “hooked” than the Big Blade. This gave the Smoothie a sharper feel at the catch. The outline of the Smoothie was the same as the successful Big Blade. In 2006, the Smoothie mold was refined with subtle changes to improve handling. This refinement resulted in the Smoothie2 Plain Edge we offer today and was the precursor to our more efficient Smoothie2 Vortex Edge and Fat2 blades."

From your website I would take issue with your diagram from June 21st 2017 and would suggest that
Fig 2 (Sadly again C2)
https://www.concept2.com/oars/how-made-and-tested/blade-path
is closer to reality as such the large red zone in your diagram- great for sales- doesn't really exist.

You will likely find thew following interesting too:
https://groups.google.com/d/msg/rec.sport.rowing/myC-tmx-wPI/zB6VhiNiBpwJ
I appreciate that Kelshnev's 2015 paper is more recent than this but as Mel has already pointed out I'm not sure you are comparing like with like.


I think it's great to see more innovation in the sport btw, I'm just not convinced about this yet...

best wishes

Stan

[lladn...@gmail.com]

Many thanks for your many insights and comments.

This project has been an “open” project after the efficacy of hydrofoil lift effect on a blade was discovered. There are no patents or copyright limitations.

With only two data sets the quantification of the speed gain is still under review - however the data and experiential observations have determined a positive effect. The number many layman testers are reporting is +5% (+3% without a 3-degree of oar pitch - see rigging and pitching instructions).

I welcome peer review and participants in this project.

Regards,
Ian Randall

[Mel Harbour]

As I said, very supportive of the efforts for innovation, but it's important that you recognise that based on the data and experimental observations you've shown so far, it's simply not the case that you've "determined a positive effect".

That doesn't mean that it doesn't exist. You just haven't (yet) demonstrated it. The evidence doesn't show it. There are glimmers of things that are worthy of further investigation, but certainly nothing remotely close enough to you being able to claim that the foils give you a 3-5% advantage. Remembering that for an international single sculler 3-5% speed advantage at race pace would represent them winning a race by more than 12 seconds, or 4 lengths in old money.

In order to be able to make your claim reasonably, you need to:

1. Eliminate from your analysis the effects of the people pulling at a different force.
2. Find some way of assessing whether them pulling with a different level of force is a consequence of the different equipment, or whether they are subconsciously influencing the setup. Quite hard to double blind the trials, unfortunately...
3. Get a large enough sample size to be able to overcome the random variation inherent in this sort of analysis - with such small sample sizes, and the small effect you're looking for, it's always going to be hard to distinguish from random noise in the data.
4. Possibly the hardest one of the lot, but arguably the most significant, work out whether blade efficiency is even a limiting factor in rowing propulsion, and by how much. For example in cycling, aero is by far the limiting factor, so a small gain there can make a big difference to overall performance. By contrast a small increase in power output has a much smaller effect on overall speed. Furthermore, the aero problem is overwhelmingly that of making the rider 'slippery'. Bike manufacturers love to claim that their new bike is going to be 5% faster, which may well be true up until you put the rider on top of it, but those differences practically disappear once the rider is in place. Intuitively, I'm not convinced that blade efficiency is a particularly big limiting factor in rowing performance, and therefore quoting an overall speed increase of 3-5% just seems implausible to me. That doesn't mean there's not benefit, but the chances of it being anywhere near that large are small.

But let me reiterate - I'm very supportive of the push for innovation - I think it's great to look at these things, try new ideas out and study them. The only thing I'm trying to do by being critical is to help that study actually work out what's making a difference and what isn't, so that we can find the right innovations in an evidence based manner!

Mel

[lladn...@gmail.com]

I value your comments Mel and agree, it's not all wrapped up by any means.
This project has been a whirlwind, not yet two years old and sharing our findings is very much in the spirit of "look what we've found!"
The big hurdle was the certification from FISA, as it has been difficult to gain participation and institutional partnership with the question of legality hanging over the project.
I look forward to engaging research, larger sample sizes, deepening scientific rigor and will continue to share data, welcome reviews and replication.

I am excited to have found google forums and the opportunity that dialogue and sharing will present.

Warm regards,
Ian

[carl]

On 13/08/2018 11:56, Mel Harbour wrote:
> Interesting stuff, but just a couple of basic criticisms of the maths that you're presenting that you might like to correct (see this pagehttps://hydrofoiloar.blogspot.com/p/documents.html)
>
> 1. You quote a table with an increase of boat speed of "upto 4.5%". But in the following table, you observe that there was an increase of power output of "upto 12.8%". But you need to be clear - Biorow doesn't measure power*output*, they measure power*input*, so you haven't demonstrated with those tables that the foil is responsible for a 4.5% speed increase. You've shown that when an athlete pulls harder, they go faster. You need to remove the effect of the different input power in order to make a fair comparison.

>
> 2. Later, you ran trials via a number of 1km pieces. You observe a difference in average times with the foil blades recording roughly 0.5 seconds faster. But the variance of the times recorded is much larger than that, so you need to account for that and determine whether the results actually achieve significance. My guess, without having actually run the numbers, is that they aren't achieving mathematical significance - in other words you can't tell whether the foils are better or not.
>
> But good to see attempts at innovation!
>
> Mel

As an engineer, versed in fluid dynamics & always interested in the
efficiency aspect of rowing, I applaud every effort made in that
direction. That said, the OP's data give rise to further concerns over
plausibility.

Thus, if one was to claim a 4% increase in speed from using a particular
device. which would be an 80-metre advantage over 2k, or 10 lengths in a
1x), that would imply an increase in useful power of around 12.5% or a
diminution in power losses due to the inherent inefficiency of the
oar/water system of as much as 1/3.

Extreme claims may be valid, but they do require extremely good evidence.

Cheers -
Carl

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Fine Small-Boats/AeRoWing Low-drag Riggers/Advanced Accessories
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[lladn...@gmail.com]

At this stage, I can only appeal to phenomena we are experiencing and the motivation behind the project. The science is being used to understand and measure what is occurring.

For me, I experienced...
- significant overnight increases in boat speed (at 45 years of age).
- lower heart rate at the given speed.
- lower stroke rating.

For a group of very senior (80+yrs) and experienced masters at Casitas RC, they experienced the same. They are getting times faster then Championship times in the age category below.

My doubles partner and I won our Masters C-Grade State Championship in a personal record time against long term superior competition. I would love to say that it was our extra training or improved technique... sadly, it came down to the equipment we employed.

Have a great row today,
Ian

[thomas....@googlemail.com]

One thought I had was perhaps if you publish the "raw" data collected from Biorow then I am sure people interested in this thread would help review further?

Personally id be interested to see each individual persons speed/power etc data rather than having it combined as I suspect that a persons technique would have a big impact on the effect, since for example. some rowers dig their blades deeper than others and would likely see a bigger benefit from these.

[Mel Harbour]

Great suggestion. Especially as any change to the equipment may change multiple things about the way a person rows, and disentangling them is a tricky problem to solve.

[power...@gmail.com]

As a 59-year-old Masters rower, let me describe my experience with RANDALLfoils. My wife (46) and I compete in the Mixed Masters 2x and in our singles. We prefer longer events from head races on up to full marathons. For Masters rowers, we train very hard rowing over 3 million meters per year (the bulk of this is on the water). We race to test the limits of our human potential, so results matter. A lot. For several years, we have had coaches tell us that to go faster we need to row more horizontal and stop going deep. Great, but how do we fix this issue? We have tried various drills and rigging adjustments, but we just couldn't solve this problem. About a year ago, I learned about Ian Randall's work and recently, I discovered that his foils are available for purchase. So we purchased two sets of foils for our Concept2 Skinny Oars with Fat2 blades. We have just completed ~150 kilometers of testing with the foils, mostly in our double but also in our singles. Overall, we are very pleased with the results. We no longer go deep, ever. In my single, I used to take an occasional very deep stroke with my port oar that really upset the boat, especially during a race. I cannot emphasize enough that the foils prevent this. Can you imagine a sprint race, where you go deep on the first stroke? That happened to me several times and it ruined several sprint races. While we don't focus on sprint racing, my racing starts are much better now.

In both our singles and our double, we row much smoother now. Our power is even on both sides so our boats are more stable. This gives us a better recovery. We are able to keep our blades off the water almost all the time now. This stability also yields more reach and better catches. Our meters per stroke are soaring and our splits are sinking.

At this point, it is hard to be quantitative about how much faster we will race with the foils. We will base our results on two upcoming head races this fall where we will compete against the same crews as in years past. But when we row better, look better and feel better, I am already sold on the RANDALLfoils. Sure, there will be skeptics who will doubt a 3% to 5% speed advantage for the foils, but what about the potential speed increases for those of us who do not already row like elite athletes? If anything, studies to date may underestimate the potential advantage of the foils for those of us who are more technically challenged by this sport. For instance, if I eliminate a 5-second loss on my first stroke of a 1000m race, the foils have already given me a 2% speed increase. That is a big deal if I am already finishing second or third in said regional sprint race. I'll report back in November after we have some race results.

Bob Symonds (Wichita, KS, USA)

[Mel Harbour]

It's again important to emphasise that no-one is saying that it's not possible that improvements are possible. And indeed if something addresses a weak link, the potential for improvement may be enormous.

The challenge is to prove that it's the case, which is a hard problem to solve. The plural of anecdote isn't, unfortunately, data. There are many things which could be at work to explain your improvements. In order to establish whether the foils are what is responsible, you need to find a way of controlling for them. Tom's suggestion of being able to access more of the Biorow raw data is a good start. At least in that way, various other effects can be accounted for.

As you rightly highlight though, you often need to account for things like 'comfort', which is very hard to quantify. It may well be that the equipment is not 'better' in and of itself, but if it provides a more stable/comfortable platform, it may work better. I'm sure many of us have seen examples of novices struggling with fine boats and then noticing that they often row better (and faster) in boats which have more resistance, but a more stable shape at the same time. Quantifying that is a tricky business.

Still harder to account for is the 'belief' factor. It's well documented that athletes do better with a race plan they 'believe in', for example, even if that's a less optimal plan in theory. The same is true of equipment. It's a form of a placebo effect. That doesn't mean it's not real, but again we have to try and understand it.

Mel

[power...@gmail.com]

Mel - Good points. I will point out though that my above observations were almost instantaneous (e.g. they occurred since we started using the foils 1.5 weeks ago) in the sense that my wife and I have logged over 18,000 kilometers since early 2013. So it would be hard for me to attribute our sudden improvements to something else other than the foils. And clearly we are going much less deep as indicated by the tape on the shafts of the oars. In fact, we are now at the proper blade depth as discussed in Biorow.

That said, I am a PhD scientist so I appreciate your desire to quantify and thereby prove that the foils may or may not make a difference. My take is that there is a wide variation in rowing technique and fitness. For my wife and I, our main limiting factor has been blade depth; hence, the potential for improving our rowing technique and speed with the foils is enormous. However, some crews row with perfect blade depth so I do wonder if they will see a 3% to 5% in boat speed by using the foils. But quite a few elite rowers do pull deep. For instance, Mahe Drysdale is shown going deep in the following video analysis of his 2016 Henley final that he lost to Obreno.

https://youtu.be/jJlqo5G5kZc

He recently finished 4th at the 2018 World Cup III just ~7 seconds behind his teammate, R. Manson. Yet that 7 seconds cost him the opportunity to represent New Zealand in the single for the 2018 World Championships. Would he benefit from the foils? I definitely want to know the answer to that question.

Bob

[carl]

This topic is most interesting to me, as a fluid dynamicist, as the
explanations for the results claimed run counter to my expectation.
Thus there's the stated assumption that immersing more than the blade
itself reduces propulsive efficiency: if we, for now, ignore the catch
& finish phases, which should already be rather more efficient (less
loss-making) than the stalled mid-stroke, that leaves the stalled
mid-stroke. It is standard knowledge that the reaction force against a
plate immersed square to a steady flow - the stalled situation -
increases with its depth of immersion & continues to increase as the
depth of its upper edge below the water surface increases. On that
basis, a deeper blade should suffer reduce slippage through the water &
so be a more effective propulsor.

I know the old coach's argument that the shaft of the blade should be
kept out of the water as, if immersed, it must be backwatering. Yet if
any of the shaft is significantly backwatering (enough to generate
measurable deleterious drag), that implies that part of the blade is
also backwatering. Observations tend to show this to be untrue, with
the "turning point" of the oar being inboard of the inner end of the
blade itself. In which case there is no drag penalty from a modest
length of shaft being immersed (& remember that drag is proportional to
the square of velocity, so is very small at low relative velocities, &
the shaft is of circular cross-section which is also a low-drag form at
low relative velocities)

I will return to this as more info & comments become available, & please
understand that I don't challenge your observations. All I would say is
that, reading between the lines, the Randallfoil appears to give you
much better control of your blades which, alone, might explain at fair
part of the benefit you have gained.

I would be very reluctant to criticise the technique of a 2x Olympic &
5x World Champion (plus 3 silvers and a bronze) of nearly 40. How many
of the world's very top athletes are as old? And your criticism of
Mahe's deep stroke technique should equally apply to that other great
Kiwi champion, Rob Waddell (1 Olympic & 2 World Golds). I think I'd cut
Mahe a bit of slack & allow him a less stellar season from time to time?

I'm not saying the system does not work, as clearly it works for you
right now, but I would look for a more solid fluid dynamic basis & more
extensive data.

Let's hope it really is a great step forward, but let's establish as
scientific basis too.

[lladn...@gmail.com]

I'd be very happy to send Valery's raw data on request via email.
The results are not public documents and I do not have permission to publish, however, I have permission from Valery to distribute privately.

Send your request to me:

randall...@gmail.com

Also, I would be happy to provide samples to sports scientific institutions interested in partnering with me.

Enjoy the water today,
Ian

[thomas....@googlemail.com]

A quick question on the Australian testing - The page reports a 3% speed increase with RANDALLfoils, however if I am reading the data correctly it is only the double that was testing the foils (the scullers kept non-foiled blades) and from the 5 runs the double did (2 without foils 3 with) the result was that the foils were on average 0.5 seconds slower over 1000m than the foils?

This is likely from fatigue but I am not sure where the 3% speed increase has come from?

[James HS]

it is always interesting to see the development - and work out why something might/might not work.

From someone who does not understand all the physics, i can absolutely see something that helps get the depth of the blade consistent could be a great help.

I see lots of rowers who have a parabolic (using as a description, not scientifically) in that the catch, go deep, hands go high and then come down towards the chest and 'pop' out with the rower looking slightly surprised as the blade springs out. i have also observed that the left and right blade are often at different depths, and the boat rolling to accommodate.

This is as opposed to an 'ideal' (to me) catching a few inches under the water, driving through horizontally and feathering out (hand heights similar).

IMHO fixing that 'fault' is what I spend lots of time doing - and consequently those rowers get faster.

The other thing I try to fix is insufficient blade depth - i.e. washing out, and the ideal (from a speed issue) seems to be a few inches burried.

I see lots of scullers who push harder than they/the system can control, and I think they (the body/brain being a clever thing) raise the blades to the water boundary or above, where it suddenly becomes easier to manage the poorer connection, and this becomes a habit - whereas what i try to coach is for them to moderate their power to a level that is appropriate per stroke (boy there is a disconnect in scullers as to how to go faster - they try to push harder at lower rate, rather than less hard at higher rate!!

So it would be really interesting (to me) if testing took place on those with what (I) think are a less efficient stroke, and those who have what I regard as a better (more horizontal) stroke.

As a background - I take novice scullers to the edge of the jetty with a blade in their hand. I get them to let it float at it's natural buoyancy point and then push it hard through the water - it slides along quite easily. Then I get them to repeat this with the blade an inch below and again push - and they nearly fall over as they are surprised that the water is 'resisting' so heavily.


James

[chr...@westnet.com.au]

While arguments of speed increases are enticing, they are notoriously difficult to quantify - especially at club level. Instead, consider the improvements to technique that RANDALLfoils can provide to a rower that will translate into better rowing, as discussed in the previous post. I am relatively new ( 4 years) to rowing, and have used the foils for the past four months rowing in a 1x. I was, I believe, the first to use them at a regatta. I found them extremely useful in controlling blade depth, instantly correcting a problem with a deep bow side blade that was affecting balance and drifting in the lane. The different proprioceptive feel also assisted in making sure the blades are loaded before beginning the drive. My rowing has improved, my coach is happy and I enjoy my rowing more. Am I faster ? Impossible to definitively say yes given so many other variables, but I suspect so. They haven’t made me an instant success, but I wouldn’t expect them too. In the hands of an elite sculler I suspect they will provide an extra edge that could well be significant. Don’t let the shortage of data stop you or your novice rowers giving them a try - you could be pleasantly surprised.

[Brian Chapman]

On Friday, 17 August 2018 16:08:28 UTC+1, chr...@westnet.com.au wrote:
> While arguments of speed increases are enticing, they are notoriously difficult to quantify - especially at club level. Instead, consider the improvements to technique that RANDALLfoils can provide to a rower that will translate into better rowing, as discussed in the previous post. I am relatively new ( 4 years) to rowing, and have used the foils for the past four months rowing in a 1x. I was, I believe, the first to use them at a regatta. I found them extremely useful in controlling blade depth, instantly correcting a problem with a deep bow side blade that was affecting balance and drifting in the lane. The different proprioceptive feel also assisted in making sure the blades are loaded before beginning the drive. My rowing has improved, my coach is happy and I enjoy my rowing more. Am I faster ? Impossible to definitively say yes given so many other variables, but I suspect so. They haven’t made me an instant success, but I wouldn’t expect them too. In the hands of an elite sculler I suspect they will provide an extra edge that could well be significant. Don’t let the shortage of data stop you or your novice rowers giving them a try - you could be pleasantly surprised.

Has the decrease in speed resulting from extra drag caused by the increase in cross section when the blade is feathered been calculated?

[lladn...@gmail.com]

Water and air both influence boat speed. Water being the heavier element has a greater influence. Dr Valery Kleshnev has quantified this influence in his 2015 paper, a small increase in oar depth or oar shaft creates a measurable change in boat speed. Anyone who has dragged a stick through water has felt the resistance water holds. The amount of wind resistance created by the foils does not negate the benefit through the water.

I have also been asked about the catch slip as the blade is so close to the surface and the results are counter intuitive. We tested with various oar pitching and found that by decreasing the angle to 3-degree (pins set at zero) the effect was a solid “locking on” sensation. There is a measurable reduction in catch slip in the data.

Exciting News: I have been contacted by two universities who are interested in replicating the trials.

I also invite anyone to do a trial. Make your own foils with pvc 90-degree angle that can be purchased from a hardware store and double sided tape. Shape the pvc with a knife and bend it in hot water (not boiling) to fit your oar. Ensure you correct pitch and rigging accordingly (see my instructions). It is worth pointing out that Valery’s trials were conducted with hand made pvc foils. The current RANDALLfoil is less than half the weight and uses less material.

Kind regards,
Ian
- -

[Kit Davies]

Might some of the benefit come from the foil acting as a kind of "wing
tip" separating the different pressures on each side of the blade?

Kit

[madmar...@gmail.com]

On Monday, 20 August 2018 12:31:54 UTC+1, Kit Davies wrote:
> >
>
> Might some of the benefit come from the foil acting as a kind of "wing
> tip" separating the different pressures on each side of the blade?
>
> Kit

Did anyone here ever row a set of the Braca blades with the very pronounced top edge hook? Not quite as big as these, but probably much the same effect.

[wmar...@gmail.com]

It will be interesting to see if there is a performance benefit in international competition. RE: Drysdale's deep blades - he's not the only one. If you look at a lot of fast scullers, their blades are relatively deep compared to what conventional coaching calls for. Italian LM2X in the late 90s. Drysdale, Waddell, Others...

At a coaching conference I asked Valery Kleshnev what his angles of blade-down meant for a goal depth of blade, and his reply was half-a-blade-width of water above the top edge. Being deeper like that probably allows the blade to push on the water and cause the boat to move past the blades more than the blades pull through the water due to less "slip" perpendicular to the face of the blade.

[davidha...@hotmail.com]

The cross sectional area of the oar shaft is greater than the area presented by the oar blade and foils.

[davidha...@hotmail.com]

I row the pair. Earlier this year, I saw an article about RANDALLfoils, which stated they were suitable for C2 and Croker oars. We use special order Braca sweep oars for the pair. I emailed Ian to ask if the foils were compatible with Braca oars. He emailed me a set to evaluate.

We are a FISA J class pair (boat age 81)

The first time we tried them was after a long primary practice. We started with a pair of oars without foils. At a 30 stroke rate we we were able to do 2:22 split. For reference, at Bled, the winning split was a 2:23.

Our coach came over with the pair of oars with foils and we changed. The first strokes were interesting, it felt heavier at the release, but I adapted quickly. The pieces were at 30 again, but I was so tired it took awhile to get to 30. The splits were at 2:15, quite pleasing for a first effort.

The next week, again we had a long practice before testing. we did back and forth rows. Unfortunately, our racing pair was not available, and we had to settle for an old, Chinese heavyweight pair (we are both lightweights). Without foils, it averaged 2:22 with a best split reading of 2:15. Again we changed oars to the ones with foils. The pieces averaged 2:12 with a best of 2:09. Again promising. See video at the end.

https://drive.google.com/file/d/1WJTt4DqIZv3Ye6Z70n2msyQqNDuBlYwB/view

I am partially disabled and we are not allowed to go out without a coach in attendance. We had four practices for National Championships. For the third one, we had some race start practice. Here is a video at the end. 38 to start, settle to 28. 2:15 after the 5 start and high 10.

https://www.facebook.com/groups/306806859494187/permalink/1028655373975995/?hc_location=ufi

If you look at my Facebook page (https://www.facebook.com/david.harralson) you will notice I row with a noticeable stern splash at the catch. Same at WRMR. In the videos, the oar is just at the surface and there is no stern splash, even at full pressure on the start strokes.

The following week we had a full race length simulation. Start at 42, settle to 30, last 200 meters at 36-38. 2:20 average split.

Gold medal at the Master's National Championships.

My pair partner (Don) is primarily a sculler. Ian shipped two sets of sculling foils for us to test. I have used them several times. Other than being careful to not let the edge of the foil catch the water, they seem fine. Since I have been in a quad, I could not get any comparative times. Don has used them several times, but is still getting used to them, with 1,000 meter times close to foil and non-foil.

Nevertheless, he took them up to Lake Merritt and got two gold medals, both lightweight and heavyweight K 1x.

I believe we are the first rowers to use the foils at a National Championship level. Three races, three golds. Not too bad for a first time effort.

The oars are now approved for Henly, are legal under USRowing regulations, and have been approved by FISA.

For sweep oars, our coach had us use two clams instead of the one we normally use. In the subsequent months, we will experiment with different spans, oar lengths and collar positions and clams with and without foils to see what works the best.

But, it seem at worst the foils will not slow us down, it appears our rowing form adapts well to using the foils. I see no reason an elite level rower could not take advantage of the features offered by the foils.

[Mel Harbour]

On Sunday, 26 August 2018 00:54:21 UTC+1, davidha...@hotmail.com wrote:
> The cross sectional area of the oar shaft is greater than the area presented by the oar blade and foils.

Cross sectional area is but one part of aerodynamics. For example, the cables on a racing bike have a tiny cross sectional area, but cause drag roughly equivalent (IIRC) to hanging a trout off your handlebars.

Mel

[Mel Harbour]

I'll again highlight that the plural of anecdote isn't data. Also, as others have pointed out, things may well work differently for different levels of technique. I can't see the second video as it's in a closed group, but in the first one, if you compare you to an international, they generally put their blades in deeper, and generally establish a higher percentage of their maximum force much earlier in the drive phase. Consequently (due to the inherent pitch on the blade) their blades are forcing themselves upwards in the water far more than yours are, and hence achieve a great deal more stability.

It could be (hypothesis time!) that the foils are helping you overcome a technical deficiency (good!). If internationals don't have that technique deficiency, then there may be negatives of the foils that would then have an effect that dominates. We simply don't know, as there isn't enough careful research yet.

Mel

[James HS]

On Sunday, 26 August 2018 02:25:22 UTC+1, davidha...@hotmail.com wrote:

so the change between blades was not just the foils but the clams, and so a gearing change? or did you use more clams that normal on both runs?

not sure how you get from the foils not slowing you down to no reason why they won't help an elite rower .... until we understand if there is a) an advantage and b) what might be producing that advantage

I love innovation, but normally like to understand it, and the shaft drag does not do it for me :)

[davidha...@hotmail.com]

Mel,

We started out with Don at port stroke. On our second row, we recorded data using our Smart Oar recording capability. The next practice, coach rigged the boat with starboard stroke because of what he could see in the data and we are faster that way.

I have a front loaded force profile. I have examined other video of us rowing, and I can see the force profile difference, although it is subtle. Eights have the most front loaded force profile, pairs not so much. My pair partner is basically a sculler, with a much more back loaded force profile. I have had to modify my rowing style to be more together when rowing at lighter pressures and stroke rates, although the differences seem to narrow as we progress up the pressure curve. Kindly note that we have rowed the pair fewer than 15 times, so are getting used to each other.

As I mentioned, I typically have a stern splash at the catch, which is indicative of a front loaded force profile, allied to starting the drive as the blade drops. The foils seem to stop that inefficiency cold.

With my previous pair partner (now retired from rowing), I rowed bow because Smart Oar data showed I was better in bow seat with that combination of rowers. We also had the riggers in different holes, different spreads, and different number of clams, amongst other things. Eventually resulted in a 1:42 split at 39 for close to 1,000 meters (I thought we were doing 2K back to the dock). Not bad for a 75+ year old rower.

Sorry about the second video. It is in my coach's Facebook page and I have not figured out how to get it out. I could ask her to make that post public.

Basically, it was higher stroke rate and increased pressure (5 stroke start 1/2, 5/8, 3/4, 7/8, full) 10 high, 10 settle. We are below race pace at the end of the 10 high, so do not need the usual 20. Still no stern splash, and the oars are buried up to the foils. Minimal bow splash as I am working at keeping my hands slightly lower into the catch.

I am not a proponent of deep blade rowing, despite some rowers using that style. I have always felt the oar was most efficient just under the surface with a "hump" of water on top. Going deeper requires more time at the catch and release and I feel I am applying rotational torque as I get the blade deeper which has the probability of upsetting the boat. It is possible to get the foils under the water (my first sculling use of the foils had the starboard oar under the water). I feel that the design of the foils increases the oar's efficiency when at the surface since there is no water spilling over the top of the blade.

It may be that different rowers styles interact with the foils in better or not so good ways. All I can say is, we had two comparison rows, with equivalent results. We had only four practices before Nationals, and neither the coaches nor us thought of trying without foils. We took our oars to Merritt and used a rented (heavyweight!,yuk) pair.

If you have any doubts, get a set from Ian and do your own testing.

[davidha...@hotmail.com]

James,

For the tests, everything was the same. One set of oars had the foils, one set did not.

It was coach who added the second clam for our practices for Nationals. Even with these big blade stiff shaft Braca oars, I typically do not use clams. We used one for our first rows, and coach added the second one for our practices leading up to Nationals. It was her call, I just row.

My rowing style typically has a stern splash at the catch, which I feel wastes some of the energy I am putting into the blade and it is not transferring all of that to the water. With the foils, there is no stern splash, so I feel all my energy is going into moving the boat, not water.

[power...@gmail.com]

I thought that I would give an update on how the foils handle in the wind. My wife and I row on a narrow, somewhat protected river in Wichita, KS. As such, we get the Kansas wind, but not heavy chop. Yesterday, we rowed in very windy conditions (sustained winds of 30 mph, gusts from 40 mph to 45 mph). On one 2-km stretch we were rowing against the wind with 1 - 1.5 foot waves. The foils were absolutely fantastic. I increased the stroke rate to 23 to 25 (from 20) and cut the recovery-to-drive ratio from 2 to 1. (This is a standard open-water technique.) The foils helped us lock in at the catch and perform a very smooth, powerful drive without going deep. As a consequence, our recovery was also smooth. We ripped right through the waves and got some very nice splits despite the headwind. When we came back to the dock after our 10 km row, we didn't have any water in our boat. While we are experience rowers and often row in wind, We have never rowed this well in chop before. I should also point out that we the foils do not get caught in the wind.

Bob Symonds (Wichita, KS)

[Mel Harbour]

On Monday, 27 August 2018 00:09:46 UTC+1, davidha...@hotmail.com wrote:
> As I mentioned, I typically have a stern splash at the catch, which is indicative of a front loaded force profile, allied to starting the drive as the blade drops. The foils seem to stop that inefficiency cold.

Just to quibble a little - a stern splash doesn't show a front loaded force profile. It shows that the blade is moving towards the stern faster than the speed of the water at that point, which implies that force has been applied before putting the blade into the water. Relatively speaking, little force is required at that point to achieve an oar speed faster than water speed as air resistance is so much lower than water resistance.

> I am not a proponent of deep blade rowing, despite some rowers using that style. I have always felt the oar was most efficient just under the surface with a "hump" of water on top. Going deeper requires more time at the catch and release and I feel I am applying rotational torque as I get the blade deeper which has the probability of upsetting the boat. It is possible to get the foils under the water (my first sculling use of the foils had the starboard oar under the water). I feel that the design of the foils increases the oar's efficiency when at the surface since there is no water spilling over the top of the blade.

When you say that you've 'always felt' a given style was most efficient, it's important to be clear about what you mean. For example, you could mean:

1. You happen to believe it, with little actually evidence.
2. When you think you've been rowing in a given way, you've been going faster.
3. When you've been rowing in a different way, you haven't learnt how to row that technique well, so have been rowing slower.

The last point is really the difference between technique and skill. You might be very skillful at a less optimal technique, and less skillful and a more optimal technique. Doesn't necessarily mean one is right or wrong, especially when you factor in different people's bodies etc!

Mel

[Peter]

On Tuesday, 28 August 2018 15:01:26 UTC+1, power...@gmail.com wrote:
> I thought that I would give an update on how the foils handle in the wind. My wife and I row on a narrow, somewhat protected river in Wichita, KS. As such, we get the Kansas wind, but not heavy chop. Yesterday, we rowed in very windy conditions (sustained winds of 30 mph, gusts from 40 mph to 45 mph). On one 2-km stretch we were rowing against the wind with 1 - 1.5 foot waves. The foils were absolutely fantastic. I increased the stroke rate to 23 to 25 (from 20) and cut the recovery-to-drive ratio from 2 to 1. (This is a standard open-water technique.) The foils helped us lock in at the catch and perform a very smooth, powerful drive without going deep. As a consequence, our recovery was also smooth. We ripped right through the waves and got some very nice splits despite the headwind. When we came back to the dock after our 10 km row, we didn't have any water in our boat. While we are experience rowers and often row in wind, We have never rowed this well in chop before. I should also point out that we the foils do not get caught in the wind.
>
> Bob Symonds (Wichita, KS)

1.5 ft waves and no water in the boat? Pull the other one unless you were in a dory. And irrespectve of foils/technique etc I'd like to see anyone doing good splits in headwind gusts to 45mph.

peter

[lladn...@gmail.com]

Thanks Bob for sharing your experience of rowing with Foils in poor conditions.
Rowing in poor conditions is a concern for many Olympic teams as the Tokyo 2020 races are to be held in the harbour.
The purpose of this design project has been one of discovery and sharing. I thank Bob for his willingness to share his experience, I too also have found an advantage in using foils in poor conditions.
Our boats are extremely buoyant, watertight and are very good at deflecting waves. Most of the water that enters our boats is from oar splash. Foils simply reduce the amount of contact between the loom and the water creating less splash. Thanks again for sharing Bob.

[James HS]

Wow ...... I row on the tidal thames and I would say that MOST of the water that enters my single is from swamping! I don't think i have ever noticed loom splash, but have noticed blade splash.

Maybe I just object to using words like 'most' rather than something more like "i have noticed a reduction in splash in my situation and think it might be ...."

James

[pmac...@sympatico.ca]

Wondering whether some portion of the improvement in speed could be due to improved balance/set.
Might not be a big differentiator at the elite level, but for Club level masters, would think better stability leading to more consistent power application would make a material difference in average speed.

[carl]

On 31/08/2018 08:30, lladn...@gmail.com wrote:

Most of the water that enters our boats is from oar splash. Foils simply
reduce the amount of contact between the loom and the water creating
less splash

It is unproven assertions which damage the case for any device.

I can believe that this device helps those newer to the sport to
maintain consistent & equal blade depths, which will have performance
advantages.

In that context alone, the claim of 5% speed advantage might make sense.

For more experienced rowers I find that claim less plausible - unless &
until regatta competitions validate it - since a 16% propulsive power
advantage (which a 5% speed improvement implies) & a distance advantage
of 100m over 2k seem beyond the realms of feasibility.

The old argument about large quantities of water coming into the boat
from blade and shaft splash is not credible. One modest wave can
entirely fill the footwell of a single, but almost no amount of messy
sculling can do that in an outing. There has long been the popular
fiction, among rowers not versed in engineering sciences such as fluid
mechanics, that boats are swamped by spray from oars & riggers, but it
is entirely without foundation. Yes, spray is impressive & may drench
you, but a racing eight can take on a tonne of water in less than a
minute from waves overtopping the sides (if you doubt that, you have
only to apply the rules for flows over broad-crested weirs, assuming
reasonable wave forms).

And if we go back to the start of this discussion:
What might be described as over-immersed shafts do not in fact
backwater, & you'd have to dig rather deep for any part of the shaft to
be backwatering. Even then, no part of the slim & circular shaft would
be moving with much speed through the water. Indeed, unless the
imaginary turning point of the blade did lie inboard of the blade's
inner end (i.e. somewhere up the shaft) the more inboard part of the
blade would itself be backwatering - which would indeed incur
significant drag.

I don't discount the possibility of the novice digging their blades very
deep, & anything that helps to control that excess must help (indeed it
must help to keep them in the boat). But, if anything, the evidence of
the fastest scullers (& of science) suggests that most rowers row less
deep than they should. The point here is that the deeper the blade
below the surface the less easily air is entrained downwards onto its
convex, low-pressure face & the consequently higher its stalled drag
coefficient will be.

Let's await some comparative top-level competition results, & prepare if
necessary to eat slices of humble pie.

[lladn...@gmail.com]

There have been a number of forum comments regarding the ‘help’ foils provide to rowers being more beneficial to some over others; foils may help “masters” or “novices” but not elites.
The assumption is that elites have reached a level in performance and technical proficiency that an improvement in design will not be beneficial or offer an advantage only marginally, if at all.

One principle of design which has governed this project is ‘Universal Access’. Where automatic doors and ramps were once only considered only for the ‘disable’, now architects are including these as standard for public buildings. Automatic doors and ramps enable everyone to enter buildings with ease, including ‘elite' door handle turners and step climbers. I have sort to make a rowing oar perform universally more effectively by seeking to enable a rower to perform a stroke with the oar automatically at the most effective depth. I have accepted the established fact that 'braking splash' has a negative effect on boat speed and understood it as influencing the design change to ‘skinny’ shafts or ‘arrows’ by our major oar manufacturers. I have simply taken this design one step further down the road.

All designers aim to create better products and aim for the ‘it just works’ experience by users and I have shown that oar can be designed to operate automatically at an optimal depth. With a fine-tuning of oar pitch and gate height, an oar with a foil has the same ‘feel’ and functionality as a standard oar, but with improved performance and usability. Any design development is for the benefit of all. In addition, this design change could benefit an elite training program by eliminating hours of oar depth drills and analysis to focus on other areas.

As for numbers, I have presented the data and analysis of this design project as they stand at the moment and await with great anticipation the results of university trials in Australia, UK and US.

"Keep your eyes in the boat",
Ian

[James HS]

Ian,

By posting about your design on a discussion board where every aspect of rowing is dissected to get at the nitty gritty of how it works (often involving years of debate as it is a complex issue) you have to accept that the same will be applied to your invention, which you assert can generate up to 5% 'improvement' in ANYONE that uses your device - including, therefore elite and/or novice.

We are doing what we always do - debating to understand how something works. Your claim is that your foils do two things (I am summarising) in consistently placing the blade at the 'ideal depth' - where the physics as I understand it state that the blade should be slightly deeper, and that by having less of the loom in the water it avoids backsplash (which I have never observed) and Drag which I have heard others say is minimal compared to the less covered blade being less efficient.

So we are just analysing how/whether we think these could work, and you have a study with I think a population of n=2 and several people who have used the blades and say that (in practice) it has given them a massive reduction in splits.

I am afraid that your use of providing building access is a red herring (I happen to specialise in making buildings accessible for disabled people) and these features are NOT a universal panacea - take for example stabaliser wheels on a bicycle - lets anyone have a go without the risk of falling off - do you really think this would help elite cyclists? An automatic door can slow down the passage of someone who would normally just have pushed their way through, stairs are much faster than a platform lift, steps shorter than a ramp and you get many more non accessible WCs in a space than accessible and so improve the 'throughput' ...... 'universal' design just does not exist in this sense (even though I specialise in this area, and have occasionally designed a theatre seat for someone arriving on a trolly, I am still only messing around in a larger portion of the bell curve and NEVER getting remotely close to the ends (or do we think universal is 90% not 100%.

So ..... to postulate that an elite sculler (for instance) could take 5 seconds out of the competition is a bold claim, and until it is established, one that my enquiring mind will still treat with scepticism and curiosity.

I think we all know that technique changes and set-up changes can have profound effects - over my years of sculling I have had some 'aha' moments where I have changed rigging and then made measurements with the empower oarlock and had 5% +
improvements (questioned here for the quantuum). And I accept that there are so many elements at work that some of this would be measurement error, some external factors, some correction of my relatively novice status (11 years sculling), some because I wanted it to be (investment), and some because I have gone from a non optimal to a more optimal setting for me and the conditions (the latest was to reduce my span, and blade length (overall and inboard) and rate higher!)

No one is calling you out for the proposition that a design change might improve speed, but I personally don't yet understand the explanation and await DATA that I can get my teeth into to understand the substantiated claims.


James

[lladn...@gmail.com]

I have already offered the raw data in a previous post and have distributed to all requests - please write to me at randall...@gmail.com

[lladn...@gmail.com]

New review of RANDALLfoils presented by Aram Lemmerer

Tested by “elite” rower - two time U23 European Champion - Jakob Zwölfer

https://youtu.be/5DSUo6IdaBs

[m...@nicholasthorn.com]

On Sunday, 12 August 2018 07:34:32 UTC+1, lladn...@gmail.com wrote:
> Greetings All,
> I would like to introduce my oar design to the Google rowing community called the RANDALLfoil - link https://hydrofoiloar.blogspot.com.au/
>
> It was discovered after considering how to eliminate all contact between the oar shaft and the water during the rowing stroke.
>
> Bio-Mechanical scientist Dr. Kleshnev measured this drag effect or "braking splash" on boat speed and found it to be a significant limiting factor on speed. See BioRow Newsletter No 173 August 2015 Dr. Kleshnev - link http://www.biorow.com/RBN_en_2015_files/2015RowBiomNews08.pdf
>
> The RANDALLfoil is a simple 90-degree strip attached to the top edge of the blade. The design serves as a hydrofoil and restricts the depth that an oar may be buried under the water during the stroke. The design is counter-intuitive and seems to go against the long-held assumption that the deeper the oar is buried the more 'grip' it gets.
>
> The effect of adding a hydrofoil to an oar has been tested independently by Dr.Kleshnev and the Australian Women's National Training Centre with results showing a 3-5% speed increase and a reduction in catch slip. Results have been published on the RANDALLfoil web page. Early adopters in NZ, UK, US and Australia are also replicating results.
>
> FISA has recently ruled that the RANDALLfoil conforms to all current laws and has allowed it to be used in competition, including all World Rowing events.*
>
> There have been many people who have assisted in the development of this design and I would like to thank the following people within the rowing community.
> - Dan Noonan, Australian Olympic Medalist
> - John Keogh, Head Coach of the Australian Women's Rowing
> - Dr. Valery Kleshnev of Bio Row
> - Nancy Churchill, Director of Masters Rowing Western Australia
> - Magnus Butlin, 2018 NSW State Masters Champion
> - Drikus Conradie, NZ International Rower
>
> "Keep your eye's in the boat"
> Ian Randall
>
> * The commercialisation of this design was a requirement for FISA certification, however, the primary intention of this project was to share this discovery with the rowing community.

Plotting watts vs boat speed seems to be dominated by the R36 datapoint; all the other steps make it them look marginally slower for the effort as measured by Biorow:

https://docs.google.com/spreadsheets/d/1ZJF5ALuz1pKmIgPBHhOyLOVkJYBgGYMCn_8ozgHPFUU/edit?usp=sharing

Interesting though, I would like to have a play with some as sorting out my digging deep in the 2x might give bow seat one less thing to complain about. Thanks for sharing these!

[lladn...@gmail.com]

Thanks for adding to the discussion Nicholas and you reading of the data through a new lens.

I conclude that it does make sense, as there is an exponential relationship between boat speed and the power that it takes to accelerate a boat.

The Biorow data shows RANDALLfoil's allow a higher output of power and we understand this to be due to the reduction in slip and higher blade efficiency.

You just seem to be able to get a better 'hold' on the water, right from the catch and deliver a more powerful stroke - resulting in a faster boat speed.

I will soon able to publish more data sets.

Kind regards,
Ian

[lladn...@gmail.com]

2018 FISA World Rowing Coaches Conference Berlin

RANDALLfoil Presentation
- A new oar with an Attached Hydrofoil Limits Diving Depth and Increases Boat Speed.
Ian Randall
RANDALLfoil, Leura, Australia

https://youtu.be/RiyqQtXDLuQ

[atkin...@gmail.com]

Hello all:
I'm pretty late to this thread, but have a few observations to offer.

1. The blade depth controversy:
Rather than endlessly argue this I note that simple experiments could settle the matter.
See: http://www.atkinsopht.com/row/bladepth.htm

2. Re the referenced Concept2 presentation:
https://www.concept2.com/oars/how-made-and-tested/blade-path
Figure 1. Assumed blade path-- No blade path in rowing is remotely like this. Such a path could be true only if the blade had zero surface area.
Figure 3. The ideal blade path-- There is nothing "ideal" about this path; it is simply the path of zero slip; no force applied to the blade. For a given oar and rigging all zero-slip paths are identical.
Observation 4. Less Slip? No, these are not at all the absolute slips--which can be as much at one meter in length.
Credit: Note that the photo of the blade path from the bridge was taken by Ken Young (RIP) of the University of Washington.
See: http://www.atkinsopht.com/row/bladpath.htm

3. The RandallFoil
There seem to be no confirming data as yet.
Extraordinary claims require extraordinary proof.
We await its presentation.

If you'd like, see also https://wp.me/p6Isot-oj

My best regards to all.
Bill

[sully]

On Wednesday, April 17, 2019 at 1:08:14 PM UTC-6, atkin...@gmail.com wrote:
> On Friday, November 30, 2018 at 5:52:42 PM UTC-5, lladn...@gmail.com wrote:
> > 2018 FISA World Rowing Coaches Conference Berlin
> >
> > RANDALLfoil Presentation
> > - A new oar with an Attached Hydrofoil Limits Diving Depth and Increases Boat Speed.
> > Ian Randall
> > RANDALLfoil, Leura, Australia
> >
> > https://youtu.be/RiyqQtXDLuQ
>
> Hello all:
> I'm pretty late to this thread, but have a few observations to offer.
>
> 1. The blade depth controversy:
> Rather than endlessly argue this I note that simple experiments could settle the matter.
> See: http://www.atkinsopht.com/row/bladepth.htm

Thank you for this. The women's coach at our collegiate club is using them and believes they are effective, no hard data however.

I have been an advocate for deeper blades, but have trouble supporting it.

One issue is what you address above, that's shaft drag from mid-drive to finish. In the above link you say:
There are those who worry about the supposed drag resulting from that portion of the shaft buried with the blade. The shaft, near the blade, is merely an inefficient extension of the blade surface area itself -- contributing weak additional propulsion, perhaps, but no troublesome drag.

My doubts: From mid-drive to finish of stroke, the blade acts as a foil, the flow over the back of the blade vs front of the blade to finish provides some lift force, given rower keeps blade effectively buried. The boat moving past the blade creates that flow. A buried shaft seems to me to be all drag as it's pulled along with the boat, the flow on the back of the blade contributes to lift, shaft does not. (I have a counter for this but not now). This is observable as you can see water frothing up off the shaft toward finish.

How am I mistaken here?

[atkin...@gmail.com]

Sully:

For reference see Figure-2 at http://www.atkinsopht.com/row/bladpath.htm
The path through the water of the center-of-pressure of the blade.

In this (a typical) case the blade path through the (stationary) water is represented by twenty calculated data points. The close-by shaft axis is not diagrammed but is essentially tangent to the slip curve for the first 15 points, normal to it for six, and tangent again for five--tangent for 20 of the 26 points. While tangent the shaft moves essentially axially through the water--no appreciable resistance possible. And while normal is slipping sternward with the blade, adding (perhaps with a splash?) an inefficient bit to the propulsion effort. There is no component of "check".

Bill

[berend.v...@gmail.com]

Dear Bill,

Thank you very much for your explanation, which I completely agree with. I have always found the calculation of Kleshnev to be wrong on this point, which he explains here:

http://www.biorow.com/RBN_en_2015_files/2015RowBiomNews08.pdf

In Equation 1 in the above Newsletter, the drag is estimated by the usual equation for drag. But the velocity in this equation, which should be the slip velocity between the blade and buried part of the stem, is treated as if the stem is standing still next to the boat - which is wrong in most cases. In fact, as you point out, the buried part of the stem typically moves faster through the water, adding a bit of additional drag in the other (the useful) direction to the oar. It is questionable how effective it is - but it certainly doesn't hurt the propulsion.

Another factor, which is not often discussed, is that the major part of the drag is given by the difference in pressure between the front of the blade and the back of the blade, and that if air would entrain behind the blade, the minimum pressure behind the blade is the atmospheric pressure, P0. I could imagine when the blade is kept deeper under the water surface, air will not be able to entrain behind the blade, and the pressure might even become lower than P0, leading to additional propulsion. I have no idea if this is actually important, or not.

One thing which I could imagine in favour of the Randall-foil, is the dissipation of the flow of water in directions perpendicular to the blade surface when the blade is entered in the water. I could imagine that when a blade is quickly entered in the water, there is some flow perpendicular to the blade, which could give a slight feeling of instability to the sculler? These currents could maybe be hindered somewhat by the foil on top of the blade? It certainly won't be major ...

Thanks for your insights and your fantastic website.

Berend.

[berend.v...@gmail.com]

Apologies! The last paragraph should have read:

One thing which I could imagine in favour of the Randall-foil, is the dissipation of the flow of water in the plane of the blade surface when the blade is entered in the water. I could imagine that when a blade is quickly entered in the water, there is some flow next to the blade, which could give a slight feeling of instability to the sculler? These currents could maybe be hindered somewhat by the foil on top of the blade? It certainly won't be major ...

[lladn...@gmail.com]

RANDALLfoil update - audio file (7:45s)

https://drive.google.com/file/d/1NSHWAqGvlwCI3RclDvBuH9wlEhaXxOKT/view?usp=drivesdk

[s.maddalen...@gmail.com]

On Sunday, 26 May 2019 08:32:18 UTC+1, lladn...@gmail.com wrote:
> RANDALLfoil update - audio file (7:45s)
>
> https://drive.google.com/file/d/1NSHWAqGvlwCI3RclDvBuH9wlEhaXxOKT/view?usp=drivesdk

I listened to this speech and found it a bit creepy; sounding so sincere as to cause doubt in that very quality.
Claiming that such a foil benefits masters novice rowers is a conveniently grey area.
Has the 3 to 5 percent speed increase been proven in international competition?

[sully]

our varsity women raced w/ them this spring. They didn't have a particularly good result so no conclusion as to whether they helped. In talking to one of the team, she didn't like them, told me she felt they removed some sensitivity and feel on the drive.

Haven't yet talked to coach about his thoughts after trying them.

[James HS]

Seemed to just be a rant about rowing not adopting innovation - yet it seems from one year to the next there can be a wholesale change of boat manufacturer who dominates - and that is serious kit expenditure, so I would beg to differ.

If benefits are properly demonstrated - rather than just the 'puff' that I currently see (I don't believe that looms in the water are a problem as I understand that the blade remains kind of stationary and the boat travels past it).

The rest of the 'claims' seem a bit counter intuitive to me - but happy to read more about the 'physics' and then to see some data on the performance gains.

I am slightly unsure about the issue of rowers not being able to properly get blade depth - if they are not able to master this technique element there may be other things that are missing in their performance?

As a coach I am always looking for performance gains - I look for most of them in the athletes first, and with coaching they get blade depth consistently where I want it - so this is not currently on my list of things to address, which may be why I am not fitting them :)


James

[carl]

If a 5% speed advantage was available, then over 2k your crew should
have gained 100 metres. That's about 6 eights' lengths.

Extraordinary claims demand extraordinary evidence.

However, I'm confused by crew talk about "sensitivity & feel". What has
that touchy-feely stuff got to do with going fast? It's only the useful
work done that moves the boat so, to me, that's adding an imaginary
faux-artistic element to the simple task of getting the blade cleanly in
& out & pulling hard - which bit of "feel" makes the boat go faster?

Cheers -
Carl


--
Carl Douglas Racing Shells -
Fine Small-Boats/AeRoWing Low-drag Riggers/Advanced Accessories
Write: Harris Boatyard, Laleham Reach, Chertsey KT16 8RP, UK
Find: tinyurl.com/2tqujf
Email: ca...@carldouglasrowing.com Tel: +44(0)1932-570946 Fax: -563682
URLs: carldouglasrowing.com & now on Facebook @ CarlDouglasRacingShells

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[alish...@gmail.com]

I have been using these for about 6 months now and with the correct set up they result in improved consistency over a race distance mainly due to the dramatic increase in stability through the front turn. The additional stability results in the ability to do a lot more work in the initial part of the drive phase. I have been rowing for 31 years and it is great to see some innovation that results in faster race times. Prior to racing with them I did a huge amount of experimenting with set up which has been fun and my trialling of them demonstrated a clear improvement in my ability to maintain boat speed.

[James HS]

On Friday, 7 June 2019 05:01:05 UTC+1, alish...@gmail.com wrote:
> I have been using these for about 6 months now and with the correct set up they result in improved consistency over a race distance mainly due to the dramatic increase in stability through the front turn. The additional stability results in the ability to do a lot more work in the initial part of the drive phase. I have been rowing for 31 years and it is great to see some innovation that results in faster race times. Prior to racing with them I did a huge amount of experimenting with set up which has been fun and my trialling of them demonstrated a clear improvement in my ability to maintain boat speed.

Any numbers you can put on that? Improved consistency and improved ability to maintain speed sound like they come from reading data?

Just curious, as so far only discussions have come from 'feel', yet % improvements have also been discussed - which sounds like it should come from numbers.

James

[sully]

On Wednesday, June 5, 2019 at 9:02:50 AM UTC-6, carl wrote:
> On 05/06/2019 02:16, sully wrote:
> > On Tuesday, June 4, 2019 at 5:20:29 PM UTC-6, s.maddale...@gmail.com wrote:
> >> On Sunday, 26 May 2019 08:32:18 UTC+1, lladn...@gmail.com wrote:
> >>> RANDALLfoil update - audio file (7:45s)
> >>>
> >>> https://drive.google.com/file/d/1NSHWAqGvlwCI3RclDvBuH9wlEhaXxOKT/view?usp=drivesdk
> >> I listened to this speech and found it a bit creepy; sounding so sincere as to cause doubt in that very quality.
> >> Claiming that such a foil benefits masters novice rowers is a conveniently grey area.
> >> Has the 3 to 5 percent speed increase been proven in international competition?
> >
> >
> > our varsity women raced w/ them this spring. They didn't have a particularly good result so no conclusion as to whether they helped. In talking to one of the team, she didn't like them, told me she felt they removed some sensitivity and feel on the drive.
> >
> > Haven't yet talked to coach about his thoughts after trying them.
> >
>
> If a 5% speed advantage was available, then over 2k your crew should
> have gained 100 metres. That's about 6 eights' lengths.
>
> Extraordinary claims demand extraordinary evidence.
>
> However, I'm confused by crew talk about "sensitivity & feel". What has
> that touchy-feely stuff got to do with going fast? It's only the useful
> work done that moves the boat so, to me, that's adding an imaginary
> faux-artistic element to the simple task of getting the blade cleanly in
> & out & pulling hard - which bit of "feel" makes the boat go faster?
>

I can think of a number of "feel' effects that hava an effect on boat speed.

An example is the sensation of a well locked finish, leading to a clean relaxed release, an extra sensation of "zing" right after the release.

Another is the sensation of the blade being directly attached to the butt to achieve effective catch timing.

The motions one does when not powering the shell that helps the boat run better, stay on keel, have much to do with sensitivity and feel.

[dhr...@gmail.com]

They're fantastic additions for any crew aiming to build confidence especially early on in their careers.

[alish...@gmail.com]

Hi James,

I am not going to put numbers on it because it is not necessary to do so as it is my personal feeling. The smallest puff of wind makes a significant difference to boat speed and it is impossible to control these variables in a outdoor sport. All I can say is that I can rate higher and take less bad strokes because of the foils. I also find that because I spend less time modulating the blade through the stroke I am more relaxed in the shoulders and my rate of fatigue is reduced which results in less bad strokes and an increased ability to maintain speed. My personal experience is that they make me faster, I row better and I take less bad strokes. I would encourage anyone that is interested in improving to give them a try and decide for themselves if they help. They are no silver bullet, if you are carrying 5kgs too many and you haven't done the training then you are still going to be slow. They are for the people that are fit, train consistently and are looking for a way to go faster on a consistent basis. They are for those that want to embrace innovation in rowing just as any cyclist will try a wheel that purports to be faster, any rower should see if the foils are for them.

Regards,
Alastair

[alish...@gmail.com]

Carl,

Can I ask how many times have you rowed with the foils?

[carl]

On 11/06/2019 23:12, alish...@gmail.com wrote:
> Carl,
>
> Can I ask how many times have you rowed with the foils?
>

One may reasonably pose questions when a claim seems excessive without
being called upon to test the thing or, by implication from your
question, to shut up. I've never used this product, but I do know a bit
of fluid dynamics and have done a certain amount of serious
experimentation with blades.

Let me pose you some questions:
1. What is the propulsive efficiency of the oar through its stroke?
2. How much extra propulsive work must there be, through increases in
the blade's propulsive efficiency, to increase boat speed by 5%?

Tricky, buts try some stabs at answers?

It has been suggested that propulsive efficiency is ~70%, but figures as
high as 80% have been waved around.

That will demand not less than 16% increase in useful propulsive work if
we take the conservative assumption that drag losses are proportional to
the cube of boat speed.

So our 70% propulsive efficiency must rise by 16% to 81.2%, while our
80% would have to rise to 92.8%. Or, in other words, the amount of work
presently dissipated would have to fall by 11.2x100/(100-70) = 37%% in
the first case and by 12.8x100/(100-80) = 64% in the second.

We can later revisit this from another, more analytical direction, but
lets start simply. Consider, for now, if those reductions in the total
power lost around the blade during the stroke seem reasonable or, as I
suggested, rather extraordinary?

[andymck...@gmail.com]

I think Carl's point about efficiencies and force are persuasive, they do make the assumption that 100% of strokes achieve 100% of the rowers capacity. You could run the numbers another way - assume a 'normal' sculler's ability to put power in the water is a normally distributed about some percentage of 'perfection' where perfection is a perfect stroke for their strength and fitness. In my case I would guess the mean of the distribution would be at about 80% of my capacity. A reasonable percentage of strokes are 'better' and occasional ones are horribly worse. Could the Randall foil change the ratio between capacity/performance? The downside of that argument is that it would imply benefits would be for less capable rowers, but as most of us in the real world aren't aiming at a 6'30" 2k in our sculls.

[alish...@gmail.com]

I take it from your answer that you haven't rowed with them. Maybe go for a row with them then comment. Your mathematical assumptions would also be then based on your experience by this time. Theoretical models of blade efficiency are so difficult to quantify with objective data as any effort to establish concrete numbers will always be scrutinised heavily - just as this forum is demonstrating. I personally will always give something a go before I comment.

[thomas....@googlemail.com]

> We can later revisit this from another, more analytical direction, but
> lets start simply. Consider, for now, if those reductions in the total
> power lost around the blade during the stroke seem reasonable or, as I
> suggested, rather extraordinary?

Following through your question, yes I think it is quite extraordinary to think that 20-30% of the energy put into the stroke is wasted by Blade inefficiency.

I assume this must be because this inefficiency in the blade results in the most "efficient" stroke from a bio mechanical point of view?

[magnus....@gmail.com]

Insisting that someone has actually used something to qualify them to ask questions or comment, especially an expert in the field, is highly specious. In F1 or aerospace even the designers and engineers themselves never actually use their own designs, let alone others’.

But being experts, and, crucially, independent, it is entirely appropriate and necessary for them to ask critical questions of anything new in their field. The more dramatic the claims, especially if unsubstantiated or made by non- independent parties (such as those trying to sell the new product), the more important it is that those questions get asked and properly answered.

Unfortunately in rowing it’s very difficult, impossible perhaps, to control for all the other noisy variables when testing design changes likely at best to have a marginal effect on performance. That doesn’t mean that we should revert instead to using anecdote as next-best evidence.

Personally, my feeling is that at the top level this design innovation will have a detrimental effect, preventing the blade from getting deep enough for maximum “grip”. At the level of those less skilled, my feeling is different: it will have the effect of bicycle stabilizers, increasing stability (and thereby, perhaps, speed) in the short run until the skill and confidence has been acquired to “go advanced” and take them off. But those are my personal feelings and they count for very little without data or other evidence. I would certainly change my mind in the light of sufficient evidence or reasoning.
Magnus

[James HS]

I think Magnus and Carl have summed it up well.

In a performance athlete, good at what they do, the increases in stated performance are hard to believe.

In novices, or those who are inconsistent/unconfident in their blade placement, the equivalent of bicycle stabilisers could allow for a higher "hit rate" in their strokes, and hence increase 'speed'.

We use a float device to help a beginner sculler, and it makes them less likely to fall in initially. But I take it off very fast as I dont wan't them to become reliant.

I would possibly see this more like the difference in automatic and stick shift, where the time to change gear is decided by the mechanics, and never learned.

James

[jordan.e...@gmail.com]

Greetings all,

Long time lurker here. Masters sculler in Tennessee. I tend to be one of those who likes to dig at the catch, and thought I'd give them a shot. I rowed daily with the foils on my C2 VE skinny blades for about a week. First of all, I won't describe it as making it impossible to go deep. However, the changes I noticed were more along the lines of "wow I'm rowing clean today.". During Sprint pieces, I saw boat speeds I've never attained before, hitting around a 1:37 split peak speed. That being said, 10K of steady state resulted in feeling tension and aches in my lower back. As a professional pilot and flight instructor, I'm very familiar with fluid dynamics, albeit of a different type of fluid body. The feeling of increased load is consistent with what I expected from the design. It essentially looks like a winglet on an airfoil to me. At the tip of a wing or airfoil, you have a significant pressure differential between the upper and lower surface (front and back of the blade). At the tip, those pressures try to equalize, moving from high to low, creating wingtip vortices and essentially rendering the outer portion of the wing useless since the laminar flow over the airfoil is negated by tumbling swirling airflow. Winglets help to make that a more gradual delayed blending, essentially adding a meter of wing to the airplane. That is consistent to me with the perception of increased load with the foils. The blade surface is essentially more effective due to less slip, so a higher speed CAN be obtained, but the load may also be too heavy on longer rows. My suspicion is foils plus some rigging modifications would reap the benefit of the blade depth without overloading.

Long story short, I'm not making mine permanent. I don't think I'd like them at a head race, and I'm not wanting to reset all rigging to fix occasional digging.

That being said, cool idea, and I'm amazed that FISA approves things like this, but won't let anyone wax a shell.

Now, back to drooling over Carl Douglass shells. Always been a fan, Carl. Saw one of your boats in person for the first time at Masters worlds in Sarasota last year. Been wanting one ever since. Just don't have an indoor storage facility.

Jordan
Tennessee, USA

[Henry Law]

On 13/06/2019 17:00, jordan.e...@gmail.com wrote:
> It essentially looks like a winglet on an airfoil to me.

And in the current, slightly controversial, discussion, it's worth
pointing out that the aerospace industry ignored winglets for decades
and suddenly discovered them, what, ten years ago? When I was
travelling regularly on business at that time they were just starting to
come in, whereas there's hardly an airliner (old or new) now that
doesn't have them. And I can't imagine that they were difficult to
design or expensive to fit: just nobody had bothered to clear the way to
their use. It /could/ be that this foil thing is another of the same.

> Long story short, I'm not making mine permanent.

To me that's significant, and is consistent with the "training floats"
analogy that someone else made. I suspect that for those without
perfect technique the Randall thingie is really helpful; for elite
scullers probably not so much.

> Now, back to drooling over Carl Douglass shells... Just don't have an indoor storage facility.

You have a garage? My CD comes in two sections. I keep it in my
(nornal-length) garage; I take it with me from home to the club and can
have it off the roof rack, rigged and onto the water in under nine minutes.

It would take me at least that long to open the boathouse, move the
storage trolleys out of the way, take the boat out of its bag (which I
surely would use, given the way boats get damaged at our club) and walk
it to the canal.


--
Henry Law n e w s @ l a w s h o u s e . o r g
Manchester, England

[jordan.e...@gmail.com]

Interesting, wasn't aware they could be split.

Yeah, Airbus knew for a while that even a flat plate on the end made a difference. They did that with the 320 series, which was launched in the mid 80's. I own glider as well, which mid 90's began using winglets to drastically improve low speed handling and performance.

Jordan

[carl]

On 13/06/2019 01:01, alish...@gmail.com wrote:
> I take it from your answer that you haven't rowed with them. Maybe go for a row with them then comment. Your mathematical assumptions would also be then based on your experience by this time. Theoretical models of blade efficiency are so difficult to quantify with objective data as any effort to establish concrete numbers will always be scrutinised heavily - just as this forum is demonstrating. I personally will always give something a go before I comment.
>

So, before even questioning the potential validity of a seemingly OTT
claim, I should spend time testing kit the claims for which appear, on
reasonable scientific grounds, to be over-sold?

You prefer me not to use my brain, & some basic science, to assess &
then query apparently implausible claims? Have you a bridge that I
should also buy?


Please give me good reasons why this device should work as claimed,
rather than as a training aid, & I will listen. Otherwise reflect the
time & cost of performing a fair, comparative test series to evaluate
these claims. And then think how presumptuous it was to tell me to
"Maybe go for a row with them then comment"?

[carl]

On 13/06/2019 17:00, jordan.e...@gmail.com wrote:

Hi Jordan -

Good points made. They were talking about wing-tip foils over 60 years
ago, at that time trying to replicate the wing-tip feathers which are
prominently used by some birds in flight. These serve an important
function for flight efficiency by controlling & restricting air-flow
around the wing-tip from the high-pressure (under) side to the
low-pressure upper surface (which generates the tip vortex, reducing
wing efficiency & wasting energy).

Some experiments around that time tried replicating tip feathers with a
bunch of small aerofoils - not very effectively. Later came the first
winged keel (the Ben Lexcen keel on Alan Bond's Australian America's Cup
winner). Only a while thereafter did tip foils appear on commercial
aircraft - & now we see tip foils replaced on some wings by an upturn of
the entire wing-tip.

Back to rowing:
Digging at the catch is a matter of technique, as is control of blade
depth throughout the stroke. Blade depth should vary smoothly through
the stroke - there's no validity in the popular belief that getting the
shaft a bit wet is bad - & as a sculler you're free to experiment with
this. Just remember that a more efficient stroke (from going a bit
deeper) is certain to take a little longer to complete, & will feel
heavier. So you have to give it that little it of extra time in the
water & not try to rip it through by pulling harder & then complain that
it is "too heavy".

If your stroke is more efficient, then that's because it is slipping
less WRT the water (all blade slip is wasted work that doesn't move the
boat). As there's a limit how much work you can sustain per stroke, you
should also consider marginally reducing the load you apply as work done
= force x distance &, in effect, the stroke has become longer not just
by the extra time taken but also by the amount by which the blade slip
has been reduced (which that extra time reflects). The which explains,
perhaps, why I don't set much store by the magic of "feel"?

A last point: a device which prevents digging at the catch may indeed
be helpful in the learning process - if you have a poor catch technique
- but seems less likely to help & not disadvantage a skilled rower.

Cheers -
Carl

PS Many thanks for your kind comments. Yes, it's good to protect any
boat from too much direct sunlight as the UV damages all finishes -
which is why today's excellent boat covers are such a good idea (they
also prtect against casual damage and stones thrown up when travelling)
- but you'd be amazed how much sun it takes to impair a clear finish.
C

[alish...@gmail.com]

Carl,

The only claim that I have made is that for me I row more consistently at high rates (race pace, where it matters) and as a result I go faster. So all I am saying is that they are faster. How much faster depends on a lot of factors and being an outdoor sport it is challenging to quantify. I don't consider my personal experience to be that radical a claim.

There is a difference between the theoretical and the actual. Take for example the Axior pitching system. In theory it is a fantastic design. In reality sediment builds up and the system siezes, the plastic also becomes brittle and breaks - fantastic when new, not so good over the long term!

Adrian Newey describes himself how the correlation between CFD and wind tunnel data and the way this manifests itself on track does not always correlate - the plight of Williams F1 at the moment reflects this issue and the way on track testing limits their ability to identify these correlation issues in a more timely manner.

I would encourage you to give them a go, you never know you might learn something from the exercise. if you need set up suggestions I can send you some changes to pitch, gate height and angle of attack that I think get the best from the foils.

I will sign off by suggesting that there are people smarter than both of us that are currently researching the foil, blade design and other elements of rigging. The design elements of the foils may just find there way into future generations of blade! Part of this research, strangely enough is on water testing!

Please let me know if you do get around the trying them.

Kind regards,
Alastair

[carl]

Not sure about the kindness of your regards, given that you switch
effortlessly to an unsolicited & irrelevant attack against the longevity
of our AxioR pin pitching systems? Why did you never bring that up with
me privately - when you advise me to go away & test something before I
discuss its feasibility? That was a pointless attack on a system of
which many thousands have been (& many remain) in worldwide service for
40 years (being, of course, subjected to neglect & physical misuse, as
is nearly every item of rowing equipment!). Hmmm.

Now to engineering science? No one working in CFD for F1 expects it to
do better than offer a reasonable (but increasingly improving)
correlation with what happens on the track. Indeed, wind tunnel testing
(of which I've a fair experience, BTW) is also an approximation to the
truth, as is ship-tank testing. The point is that we attempt, by these
methods, to simulate mathematically fiercely challenging physical
situations. That you try to use that to question physical fundamentals
is really not smart.

I've done serious research into oar design & performance so I might,
just possibly, have a modest insight into what happens around a working
blade. But I was addressing the fundamental physical limits within
which one must assess a claimed 5% speed-gain.

You may not know that, if you do change the actual fluid flow situation
around the blade by a given design change to thereby increase boat
speed, that a) can only come from an increase in the blade's propulsive
efficiency, b) there's limited scope for such improvements, since the
blade is already quite an efficient propulsor when well-used, & c) a 5%
speed improvement in a good rower is going to require more than a
conservatively-stated 16% increase in that propulsive efficiency. While
that may not be impossible, it is definitely implausible that you will
so greatly diminish the gap between current blade efficiencies & the
total impossibility of a 100%-efficient blade.

As explained in another response, any increase in blade efficiency must
- immediately & significantly - increase the duration of the power
stroke. Think about how that will feel to the average rower. That's
why rowers complain that going a bit deeper means their blades extract
later than those of their crew-mates, & why we're tempted to row less
deep if we can't sustain the pace. Remember that the blade should not
(ideally) slip through the water as all slip is wasted work (= the force
x the distance slipped, put simply) that did not move the boat.

Which is why any performance claim must first be measured against what
is theoretically possible, accepting the impossibility of closely
approaching, let alone equalling, 100% propulsive efficiency. There's
only so much room in which to play.

[madsh...@gmail.com]

Carl, I am most likely wrong, but when I have previously read your comments regarding blade depth, one of the points I took away was that placing a bit deeper helped prevent entrainment of air on the low pressure side of the blade- this was useful as air would provide less lift compared to water and so the blade would slip more, giving that ripping feeling (forgive the clumsy description, hopefully you get the gist!). However the randall foil looks to modify the high pressure side of the blade- which wouldn't suffer such issues. Surely there would be greater benefit from placing the lip of the foil on the other side so that when the blade was placed (with the lip on/ just below the surface of the water) it would make a much more tortuous path for air to get to the low pressure side of the blade, which could possibly help in reducing slippage? Reading the comments above on wings there is talk about the bleeding from the high pressure to low pressure areas, but in this instance are we not also concerned about the bleeding to/from the ambient conditions? If you look at endplates on wings/ spoilers used in motorsport the area of the plate associated with the suction side is usually much greater than that of the high pressure side- I (possibly incorrectly) thought this was again due to trying to prevent bleeding from the surroundings, so possibly this is a useful analogy?

feel free to mock me if I have got the wrong end of the stick!

[carl]

On 14/06/2019 16:56, madsh...@gmail.com wrote:
> Carl, I am most likely wrong, but when I have previously read your comments regarding blade depth, one of the points I took away was that placing a bit deeper helped prevent entrainment of air on the low pressure side of the blade- this was useful as air would provide less lift compared to water and so the blade would slip more, giving that ripping feeling (forgive the clumsy description, hopefully you get the gist!). However the randall foil looks to modify the high pressure side of the blade- which wouldn't suffer such issues. Surely there would be greater benefit from placing the lip of the foil on the other side so that when the blade was placed (with the lip on/ just below the surface of the water) it would make a much more tortuous path for air to get to the low pressure side of the blade, which could possibly help in reducing slippage? Reading the comments above on wings there is talk about the bleeding from the high pressure to low pressure areas, but in this instance are we not also concerned about the bleeding to/from the ambient conditions? If you look at endplates on wings/ spoilers used in motorsport the area of the plate associated with the suction side is usually much greater than that of the high pressure side- I (possibly incorrectly) thought this was again due to trying to prevent bleeding from the surroundings, so possibly this is a useful analogy?
>
> feel free to mock me if I have got the wrong end of the stick!
>

It's an excellent stick, & I think you're holding it by the pretty much
the right end. I hope, further, that I'd never mock if I thought you
wrong. These are tricky concepts for us all.

As you indicate, the deeper blade discourages air entrainment, which
arises from the proximity of the water surface to the low pressure zone
behind the blade. It's a necessary & inevitable fact that the pressure
fall behind the blade, & contrary to popular belief it is largely the
fall in pressure in the water currently attached to the back of the
blade which provides the resistance to blade slip.

Our problem is that if we load up a blade which is held close to the
surface, air soon flows from the free surface & down into this
low-pressure zone. Then you have atmospheric, not sub-atmospheric,
pressure wherever the air goes & the blade loses much of its connection
with the water, so it slips face first & feels lighter to pull.

That's just a version of the flow separation problem you get when a wing
stalls in air - except that then you have only a single fluid phase -
air. The better example is with sailboat keels & rudders, when air is
able to enter the low pressure zone on the weather face of the foil
(foil = keel or rudder) & travels down that face, causing flow
separation - separation between the water & the foil's low-pressure
surface. You get a sudden loss of lift - the pressure depression across
one face of the foil on which the working of all foils & wings
absolutely depends. This aeration on the rudder causes your boat to
suddenly lose its steering & veer into the wind. If you get it on the
keel it will as suddenly start making lots of leeway & losing speed and
controllability.

As you suggest, a reverse lip on the upper edge of the blade would, if
itself below the water surface, help to delay or prevent blade aeration
with the consequent increased slip. However, it might give problems on
the recovery if you touch the water.

Fortunately, water is a dense medium, so responds (relatively) slowly to
changes in internal pressure, taking time for the low-pressure created
behind the blade to make the surface fall & start aerating the back of
the blade (& creating your showy, frothy but inefficient puddle). As
long as the top edge of the blade is sufficiently below the original
water surface (which also depends on the load applied, which varies
through the stroke) its convex face will stay fully covered.

So technique is king!

[carl]

On 14/06/2019 20:39, carl wrote:
>It's a necessary & inevitable fact that the pressure fall behind the blade, & contrary to popular belief it is largely the fall in pressure in the water currently attached to the back of the blade which provides the resistance to blade slip

a poor edit, so please try this:

"It's a necessary & inevitable fact that the pressure falls behind the
blade &, contrary to popular belief, it is largely that fall in pressure

in the water currently attached to the back of the blade which provides
the resistance to blade slip"

[carl]

On 11/06/2019 23:09, alish...@gmail.com wrote:
> Hi James,
>
> I am not going to put numbers on it because it is not necessary to do so as it is my personal feeling. The smallest puff of wind makes a significant difference to boat speed and it is impossible to control these variables in a outdoor sport.

But you presumed to tell me to test this device before commenting.
That's a double standard, when all that now matters to you is your
subjective opinion. Races are won by going faster, & a specific,
unambiguous claim was made of a 5% speed increase.

All I can say is that I can rate higher and take less bad strokes
because of the foils. I also find that because I spend less time
modulating the blade through the stroke I am more relaxed in the
shoulders and my rate of fatigue is reduced which results in less bad
strokes and an increased ability to maintain speed. My personal
experience is that they make me faster, I row better and I take less bad
strokes.

A reasonably competent sculler does not take bad strokes. Nor are they
"modulating the blade through the stroke" (whatever that might mean).

I would encourage anyone that is interested in improving to give them
a try and decide for themselves if they help. They are no silver
bullet, if you are carrying 5kgs too many and you haven't done the
training then you are still going to be slow. They are for the people
that are fit, train consistently and are looking for a way to go faster
on a consistent basis. They are for those that want to embrace
innovation in rowing just as any cyclist will try a wheel that purports
to be faster, any rower should see if the foils are for them.

Sport abounds with those who will try & then reject any number of
devices which promised them something for nothing, & those who offer no
rational or consistent justification for what they claim will boost the
performance of the user of that kit.

I note that you now claim an equivalence between this device & losing an
extra 5kg, yet many top rowers tend to carry extra body mass, sometimes
rather more than 5kg, through the off-season yet compete very
effectively in head races

I understand that you are keen to promote the Randall Foil. Maybe it
offers benefits for less-experienced rowers. But you offer no coherent
basis for the apparently hyperbolic across-the-board performance-gain
claim, instead trying to shout down my questioning which derives from
basic science, of the feasibility of a gain in performances matching
that claim.

[A. Dumas]

carl wrote, on 16-06-2019 16:59:
> I understand that you are keen to promote the Randall Foil.

Suspiciously so.

[power...@gmail.com]

I have been using the foils for almost one year now and am finally getting some meaningful race results. Last year, my wife and I focused on rowing the 31-mile Boston Rowing Marathon in the double. While we really enjoyed using foils in that event, our results are difficult to evaluate due to weeds on the course (we had to stop and back up 15-20 times to clear weeds from our fin). We did, however, finish in the top 25% of all boats.

I started rowing in the fall of 2009. Since that time, I have rowed almost 27,000 km combined on the water and the erg. I set my best 2K time (7:12.2) in 2011 and came within one second of matching that this past February. In terms of Concept2 rankings, I am best at 5K pieces and worse at 1K pieces and in between on 2K pieces. In summary, my fitness has been relatively constant since 2012 and my physiological strength is head racing rather than sprinting. I am also a lightweight (5'-8", 160 lbs).

Between 2011 and 2017, I have completed 15 1K sprint races in my single. I would rate two of these races as excellent with good starts, good overall speed, and great overall times (e.g. raw time in the low four minute range). However, in the 13 other races, I had various problems that slowed me down. My biggest problem has been very bad starts that alone cost me several seconds and one or more placings in the medals.

In May, I finished 2nd out of 6 in the Men's F 1x at the Dogwood Masters Classic in Oak Ridge, TN using foils. My results were a dream, especially since I have not done a sprint race in my single for two years. Sure, I have areas for potential improvement (e.g. gearing seems heavy since the foils have such great connection with the water) but I am now a real competitor in sprint races. I have never had such confidence with my starts until I started using the foils. I am gaining confidence, getting faster, and getting older. This is a great combination for a 60-year-old masters rower.

Do I have hard numbers comparing results with foils and without foils? No, but who cares. I row with more control, confidence and speed with the foils so that is what matters. The bottom line is that the foils help me do better. I race to do my best and to win medals so I like that.

[carl]

I see that you've raced both in the UK, in the original Boston Marathon,
as well as in the USA. Years ago we didn't get today's accursed weeds
problem in the R Witham - is this due to changes in agricultural
practices, reduced pollution or more, or to rising global temperatures,
I wonder?

Yours is the kind of information that helps in evaluating a product.


I note in particular your comment that, with the foils, the gearing
seemed heavy. That's the first meaningful observation. As I've already
pointed out, you can't increase propulsive efficiency without reduced
slip, so pulling a more efficient oar _must_ feel "heavier".

You've also addressed the matter of confidence. Good rowing,
particularly good sculling, is an art form. Some rowers find blades
hard to control while others don't. This can be down to lack of
confidence - a fear that if you load up early the blade will misbehave,
so anything which seems to stabilise the blade at the catch must
increase confidence & thus help you to load up sooner.

This discussion has seemed adversarial because a claim was made which
implies this device allows one to come too close to the absolute limits
imposed by science when the reality is that you can't get very close to
100% propulsion efficiency in fluids. But no one here has said that,
where a device serves as a useful aid to blade control, that won't
improve confidence & hence performance - in those who need that help.

The next questions are:
1. once confidence has been gained, is return to a more standard blade
problematic for the user?
2. does this device help the elite rower?

[atkin...@gmail.com]

Carl is right:
". . . you can't increase propulsive efficiency without reduced slip, so pulling a more efficient oar_ must_ feel "heavier"."
Amen

[carl]

On 18/06/2019 15:57, atkin...@gmail.com wrote:
> On Tuesday, June 18, 2019 at 9:00:50 AM UTC-4, carl wrote:
>> On 17/06/2019 18:51, power...@gmail.com wrote:

<snipped>

>
> Carl is right:
> ". . . you can't increase propulsive efficiency without reduced slip, so pulling a more efficient oar_ must_ feel "heavier"."
> Amen
>

Thanks, Bill.

It's not such a tough one to grasp, but it's not generally appreciated.

Yet it's apparent in some of the great scullers (e.g., but not only,
Waddell, Drysdale) - how deep they cover their blades.

We know that rowing deeper feels heavier (less slip, because you're
connecting with more water, so you move it less, giving that larger mass
of water less kinetic energy). We know that rowing shallow is easier
(more slip, more shear, more kinetic energy imparted to that smaller
mass of water, stroke done sooner). But armchair experts still tell us
those champions would be faster if they didn't go so deep - doh!

[wmar...@gmail.com]

At the FISA Coaches Conference in Canberra (2000?) the "crew of the year" was the Italian LM2X. One of the Danish coaches asked/commented to the crew's coach if the blades were going deeper than conventional thought - and the Italian gentleman said "yes, because it's... better".

[carl]

On 19/06/2019 04:54, wmar...@gmail.com wrote:
> On Tuesday, 18 June 2019 19:06:09 UTC-6, carl wrote:
>> On 18/06/2019 15:57, atkin...@gmail.com wrote:
>>> On Tuesday, June 18, 2019 at 9:00:50 AM UTC-4, carl wrote:
>>>> On 17/06/2019 18:51, power...@gmail.com wrote:
>> <snipped>
>>>
>>> Carl is right:
>>> ". . . you can't increase propulsive efficiency without reduced slip, so pulling a more efficient oar_ must_ feel "heavier"."
>>> Amen
>>>
>>
>> Thanks, Bill.
>>
>> It's not such a tough one to grasp, but it's not generally appreciated.
>>
>> Yet it's apparent in some of the great scullers (e.g., but not only,
>> Waddell, Drysdale) - how deep they cover their blades.
>>
>> We know that rowing deeper feels heavier (less slip, because you're
>> connecting with more water, so you move it less, giving that larger mass
>> of water less kinetic energy). We know that rowing shallow is easier
>> (more slip, more shear, more kinetic energy imparted to that smaller
>> mass of water, stroke done sooner). But armchair experts still tell us
>> those champions would be faster if they didn't go so deep - doh!
>>
>> Cheers -
>> Carl
>>


>

> At the FISA Coaches Conference in Canberra (2000?) the "crew of the year" was the Italian LM2X. One of the Danish coaches asked/commented to the crew's coach if the blades were going deeper than conventional thought - and the Italian gentleman said "yes, because it's... better".
>

Yup!

Progressively immerse a plate into a flow with its plane perpendicular
to the stream & the force against that plate increases steadily from
when its lower edge makes initial contact with the surface until its top
edge is well below the water surface.

A simple experiment, with easily measured results, yet rowers & coaches
don't think or dare to try it. Instead they are disconcerted by the
increased resistance of the deeper blade & cling to the myth that
immersing any part of the shaft must inflict a drastic drag penalty.
Which begs a couple of questions:

1. Where, along the blade & shaft, is the actual point of rotation in
the water? (Answer: at mid-stroke it turns about a point significantly
inboard from the inboard end of the blade, & the more so the harder you
pull.)

2. How fast is any supposedly adverse flow around the shaft, & how much
adverse drag might that incur versus the deeper blade's enhanced
performance? (Answer: relative velocity at worst is very low, the shaft
cross-section is slim & its circular cross-section has a low drag
coefficient compared to any part of the blade. And drag losses on the
shaft, being proportional to frontal area & the cube of relative
velocity, are very low.)

If we cling to convention we may be doomed to perform conventionally.

[lladn...@gmail.com]

Dear Bill and Carl,

Thank you for your continued interest in the hydrofoil oar project and your contributions on this forum.

I have previously written to you both personally inviting you to trial for yourselves my oar adaptation. But for various reasons you have passed on that offer.

Again, I wish to offer a hand of friendship and commit to the common purpose of progressing our sport.

The original premise of the project was based on a discovery and seeking to understand it. As testimony on this forum presents, this device is making adopters faster, row better, learn faster and enjoy the sport more and we are seeking to understand why. The foil is solving many long term design and performance issues people have addressed with existing oars. But to my surprise, this design appears to be a threat to you - there is simply no need. Test the design yourself and explain why the oar is behaving as you will observe - even disprove testimony and findings.

The accusation that you made in recent posts that proponents of this design are sitting in armchairs sprouting conventional opinions ... this is simply untrue and unfair. I am a student of this sport and look to leaders, like yourselves, to lead and to guide. I have spent hours out of my armchair, despite the mocking of the conservative crowd, on the water with rowers at all levels of the sport and every test is affirming the efficacy of the design. I am not a threat to you and this design is having a positive influence on users experience and importantly performance.

I am calling on you now to test this design yourself or allow someone you 'authorise' to do so and to contribute constructively to the project.

I am working to progress our sport in partnership and within the rowing community,

Faithfully and respectfully,
Ian Randall

[Kit Davies]

It would be nice if oarmakers designed their blades to float naturally
properly buried, rather than with the top edge at the surface. Or
better, provide a means to adjust at what level they float.

When I focus on blade depth, I find keeping them properly buried
requires a noticeable effort lifting the handles with the arms & shoulders.

Kit

[wmar...@gmail.com]

On Wednesday, 19 June 2019 11:27:16 UTC-6, Kit Davies wrote:
> It would be nice if oarmakers designed their blades to float naturally
> properly buried, rather than with the top edge at the surface. Or
> better, provide a means to adjust at what level they float.
>
> When I focus on blade depth, I find keeping them properly buried
> requires a noticeable effort lifting the handles with the arms & shoulders.
>
> Kit

You could try adjusting the pitch a little - depth at the catch/early drive can be achieved partly by how you catch and partly by having perhaps a degree less "stern" pitch - and vertical pins instead of outward pin pitch.
> >

[carl]

Ian -

I'm sorry that you're peeved. You were challenged on a generalised
performance enhancement claim which evidently overstepped the physical
limitations that apply to oared propulsion. But no one suggested that
your device might not benefit a sector of the rowing public. Indeed, it
seems entirely plausible that something which helps rowers to be
comfortable at the catch where previously they were not is likely to be
beneficial - to those rowers.

This is a rowing newsgroup - the oldest on the Internet - & it might be
said that you're using it for free publicity without contributing much
in return beyond repeated assertions of 5% speed advantage. "Introducing
RANDALLfoil - 5% speed advantage" & hammering on about it is shameless
puffery. Should we welcome "a major drinks company" telling us how
their various drinks will surely help our performance? Should we rush
off to buy some when, on scientific grounds, it's entirely obvious that
their claims are hard or impossible to justify?

We're you to quit making assertions &, rather, enter into a dialogue or
discussion of how, where & why it is that your device can yield such
vast performance gains (5% is indeed a vast gain) then no one would, I
hope, wish to shoot you down. But when you just get ratty, & start
insulting the wit & competence of people you don't know from Adam, then
the plot is lost.

As for your childish suggestion that I might ever think your device
somehow challenges my interests - well, that's truly ludicrous. As a
rower I welcome all new ideas & I welcome all friendly competition. I
also welcome good arguments, civilly & rationally advanced. So why on
earth should I bother to test your device before commenting on your
claims, any more than I should test "a major drinks company's" range of
soft & alcoholic drinks before I question any claims they might choose
to make?

You piously claim, "I am working to progress our sport in partnership
and within the rowing community". Well, I think you're shamelessly
promoting your wares in a free forum, but when someone who might just
possibly understand the science of fluid dynamics better than you
questions your claims you go all petulant, flounce & fall over yourself
at the first hurdle. And then there's that uncharming alisherwood, your
acolyte or alter ego ...

Enough! Tomorrow's a busy day with already too much to do, so I'll
leave it there.

[madmar...@gmail.com]

On Thursday, 20 June 2019 01:49:49 UTC+1, carl wrote:

I would normally let a rant by Carl go through to the keeper, but the astonishing rudeness and hypocrisy in this one needs to be called out.


<pulls pin, rolls in grenade...>



Carl - you're being rude, even by your standards.

Carl - you shamelessly promote your own wares here.

Carl - you claim to welcome new ideas, but you don't (not unless they are yours). I've worked for you and it's your way or the highway on everything even if you are at times completely wrong (I could give a number of amusing examples...).

Carl - Ian has every right to be a little peeved since you've behaved like a pompous pig and a bit of a bully in this schoolyard (ie this forum).

Carl - most of your successful products have not been as scientifically proven as you like to portray. Many are exactly the same as Ian's...novel ideas based in sound theory, then experimented with. It's a bit cheeky to hold Ian to a standard that you have not been!

Carl - you're not going to test this product because it might challenge the notion that you know everything, and you haven't rowed for a great number of years so in all likelihood would struggle to feel the nuance in any equipment.


As for the insult about Al Isherwood and the backhanded suggestion that he might be an alter-ego for Ian, I can assure the other readers that Al is real (I'm pretty sure you can look up his AUS rowing career on the FISA website) and is a highly experienced and respected coach on the Yarra River. I know both him and his wife (whom I coached as a novice). I have not met Ian. There are plenty of Carl Douglas acolytes out there, so I'm not sure what your beef with that is!



Ian - Don't mind Carl. You are not the first person he's been rude to. He's well known for it. Consider it a badge of honor!

Ian - Irrespective of the possible benefits of your idea, your big mistake was to promote a number that you can't prove. However, to be fair just about any performance number for any rowing product is impossible to quantify due to the nature of the sport.



Back to the original topic:

I think the concept is sound. Many people have (in this and other discussions) agreed that reducing slip is a good thing and would have performance benefits. The only *real* way to know if this product works for you is to test it (the same way we do for boat hulls and oars). Not everyone will feel a benefit or like the changes that they do feel (just like some people don't like other rowing products).

It would be interesting to see what rowing with only one foil attached feels like. Would a sculler be like a one legged duck, going in circles? Could you feel the difference in your hands during the drive?




All - before Carl blasts back at me, I used to work there and left after some disagreements about how the world works. He's a fascinating and talented designer, but by God he's a bugger to work for! Since my leaving he has made up a lot of stories about me that are completely false and has exaggerated others wildly. At times it is amusing to hear back through the grapevine how I'm responsible for some problem or other at CDRS, especially the ones that pre-date my arrival or happened after I left. In some industries one might consider a defamation action, but it's just not worth bothering about given his well known grumpy reputation - the people who count already take many of his personal comments with a grain of salt.

[atkin...@gmail.com]

Hi All:

"It would be interesting to see what rowing with only one foil attached feels like. Would a sculler be like a one legged duck, going in circles? Could you feel the difference in your hands during the drive?"

What a simple good idea. You might not learn much, but you'd surely see if there were a significant difference.

Bill

[magnus....@gmail.com]

I believe Carl has done something not dissimilar in the context of blade depth discussions, by slicing off the top few centimetres of blade on one side only, going for a scull and demonstrating that a sculler can't tell the difference

[carl]

On 20/06/2019 15:04, magnus....@gmail.com wrote:
> I believe Carl has done something not dissimilar in the context of blade depth discussions, by slicing off the top few centimetres of blade on one side only, going for a scull and demonstrating that a sculler can't tell the difference
>

Correct. I sliced off a parallel strip about 2cm wide, for half the
length of the blade from the tip, along the top edge of one of a pair of
sculls. Just one of a set of experiments on blade design & performance.

My understanding, from this & other tests that I've made, is that the
loss of that much of the blade area was compensated by the consequent
reduction in air entrainment behind the blade thanks to due to the
greater distance of that part of its top edge below the surface.
Surprisingly, it didn't affect how the blade feels to use, & the boat
still goes perfectly straight.

[thomas....@googlemail.com]

On a similar line I once landed from an outing and noticed one scull handle was about 5cm shorter inboard than the other for that outing - completely hadn’t noticed which made me somewhat relax my concern about whether or not to adjust my blades 1-2cm because of conditions.

My takeaway was that as rower we are actually a lot more adaptable than we realise

[berthold....@googlemail.com]

Hi Bill,

it´s the lame duck - I can tell you!
I rowed around 700 km mostly with foils (Braca sculls). Due to contact with driftwood, bottles and stuff like that one foil got loose. I fixed it (a bit too hasty and maybe the glue was overaged) but lost it some sessions later.
You`ll notice one-sided an immediate lack of pressure. For me it was 3 more strokes when I noticed something was completely wrong. Difficult to return to the boathouse...

One advantage of the foils is that it´s easier to stabilize the boat against rolling motion. This is because you always feel conneciton to the surface through the blades. Rowing a Douglas racing shell, for me it´s an advantage in choppy water.
Once you are used to the Randallfoils it takes some time to get used to sculls without foils again. Berend was right in his assumption: a slight feeling of instability - which suddenly gets dominant because it was nearly completely eliminated when rowing with foils.

Discussion here is mainly about advertising promises, proofing, data etc.
I´d like to talk about some personal experiences.
I´m a 52 year old masters rower (mainly 1x but also 2x). Personal best around 3:42 at 1k in calm condition. Rowing around 3k/year.

Is it an advantage to row with Randallfoils...to be faster?
Yes and no. It depends on wheather conditions, stroke rate, boat/scull-
characteristics and your personal settings and fitness.

What you get is simply a bigger blade with less slip. With all advantages and disadvantages this may have for your personal rowing style. If the complete package fits - you´ll be faster!

Using them at a 1k masters regatta?
Depends on stroke rate you´re able to generate. Me, I do max. 34 str/min when rowing without foils. At race-speed with foils it´s automatically lower...30 str/min. This is due to "heavier gearing" which is in reality less slip and "bigger blade.
According to Valery Kleshnevs calculations Randallfoils are not such efficient at strokerates higher than 30.
But if you like heavier gearing at low stroke rates you´ll get certainly advantages when racing.

Using them for training purposes?
Yes. They create incredible, constantly clean strokes. Your body "learns" a nearly perfect motion - and will remember this movement pattern.
You think your blade management is clean? Try with Randallfoils and you have to rethink...
I personally use sculls with and without foils alternately.

Fun factor?
Unbeatable! I gave my sculls with foils to other rowers and always saw a grin in their face!

Just my two-cents...

Berthold

[madmar...@gmail.com]

On Thursday, 20 June 2019 17:04:19 UTC+1, thomas...@googlemail.com wrote:
> On a similar line I once landed from an outing and noticed one scull handle was about 5cm shorter inboard than the other for that outing - completely hadn’t noticed which made me somewhat relax my concern about whether or not to adjust my blades 1-2cm because of conditions.
>
> My takeaway was that as rower we are actually a lot more adaptable than we realise

Jonny via googlegroups.com

13:11 (4 minutes ago)

to

On Thursday, June 20, 2019 at 5:04:19 PM UTC+1, thomas...@googlemail.com wrote:
> On a similar line I once landed from an outing and noticed one scull handle was about 5cm shorter inboard than the other for that outing - completely hadn’t noticed which made me somewhat relax my concern about whether or not to adjust my blades 1-2cm because of conditions.
>
> My takeaway was that as rower we are actually a lot more adaptable than we realise

We are very adaptable - at least until we injure something!

This is part of what makes quantifying rowing performance gains (in equipment or technique) so hard.

I'm fairly quick to notice something that impacts my comfort. Different grips, different inboards (creating an uneven finish), very short or very long inboard that radically alter my work position and how my finish reaches my body.

I'm not so sure that I'd notice that the out board on one oar was different, and it might take me a longer session to notice if my gearing had been altered by a little.

It would be interesting to know if I'd notice two different blade types (ie C2 big blade one side and a smooth vortex the other?) if the oars otherwise looked the same (shaft, grip etc), and I do recall many people commenting on Carl's modified blades, although I never rowed them.

Berthold has given us one answer about the foils and ducks, which is something that would be interesting to test out.

I've previously wondered if there was any merit in having a differing oar set up when racing on an open 2k course hit by a cross wind. A different gearing or blade type on one side might help to counter the effects of the cross wind?

[Kit Davies]

On 20/06/2019 13:31, atkin...@gmail.com wrote:

> Hi All:
>
> "It would be interesting to see what rowing with only one foil attached feels like. Would a sculler be like a one legged duck, going in circles? Could you feel the difference in your hands during the drive?"
>
> What a simple good idea. You might not learn much, but you'd surely see if there were a significant difference.
>
> Bill
>

There was an elite pair, international standard I believe but I forget
who, who tested out big blades when they came on the scene by rowing one
side big blade and one side macons.

AIUI, the verdict was there was not as much difference as one might suppose.

Kit

[atkin...@gmail.com]

Kit:
One would expect a noticeable difference if the variable were a significant change in blade surface area, immersion depth, or inboard.
But it is hard to see how the addition of a bit of surface area, essentially normal to the main blade surface, could have much of an effect.
Bill

[gsl...@gmail.com]

On Friday, June 21, 2019 at 8:35:54 AM UTC-7, atkin...@gmail.com wrote:
> Kit:
> One would expect a noticeable difference if the variable were a significant change in blade surface area, immersion depth, or inboard.
> But it is hard to see how the addition of a bit of surface area, essentially normal to the main blade surface, could have much of an effect.
> Bill

A couple of years ago I rowed with one Macon and one C2 Vortex smoothie. Closed my eyes and did a start followed by a high thirty. Did this several times. Then switched which side had the Macon and did it again. I rowed straight each time.

In a few subsequent rows I swapped out my Macons for the Smoothies between pieces. I think there was a slight advantage to the Smoothies but it was pretty hard to tell if it was above the noise.

I'm sure I could get clear results with a lot more testing, but it does take a fair amount of effort to get good results. There are usually other factors that are much more important in how well I row and race than which oars I'm using.

I do think the better you row the less difference equipment makes. At one point I found hatchets easier to row with than Macons but not anymore.