Introducing RANDALLfoil - 5% speed advantage

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lladn...@gmail.com

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Aug 12, 2018, 2:34:32 AM8/12/18
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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

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Aug 13, 2018, 6:56:54 AM8/13/18
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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

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Aug 13, 2018, 4:45:07 PM8/13/18
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<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

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Aug 13, 2018, 6:23:25 PM8/13/18
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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

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Aug 14, 2018, 4:49:44 AM8/14/18
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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
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lladn...@gmail.com

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Aug 14, 2018, 7:05:44 AM8/14/18
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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

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Aug 14, 2018, 10:42:09 AM8/14/18
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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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lladn...@gmail.com

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Aug 14, 2018, 4:51:29 PM8/14/18
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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

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Aug 15, 2018, 8:27:36 AM8/15/18
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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

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Aug 15, 2018, 8:29:33 AM8/15/18
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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

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Aug 15, 2018, 11:19:22 AM8/15/18
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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

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Aug 15, 2018, 11:34:47 AM8/15/18
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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

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Aug 15, 2018, 12:59:05 PM8/15/18
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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

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Aug 15, 2018, 8:47:36 PM8/15/18
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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

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Aug 15, 2018, 10:30:50 PM8/15/18
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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

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Aug 16, 2018, 6:51:09 AM8/16/18
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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

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Aug 16, 2018, 7:45:21 AM8/16/18
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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

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Aug 17, 2018, 11:08:28 AM8/17/18
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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

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Aug 19, 2018, 10:29:49 AM8/19/18
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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

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Aug 19, 2018, 5:16:10 PM8/19/18
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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

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Aug 20, 2018, 7:31:54 AM8/20/18
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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

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Aug 20, 2018, 8:40:40 AM8/20/18
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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

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Aug 21, 2018, 3:08:25 PM8/21/18
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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

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Aug 25, 2018, 7:54:21 PM8/25/18
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The cross sectional area of the oar shaft is greater than the area presented by the oar blade and foils.

davidha...@hotmail.com

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Aug 25, 2018, 9:25:22 PM8/25/18
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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

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Aug 26, 2018, 3:26:56 AM8/26/18
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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

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Aug 26, 2018, 3:31:43 AM8/26/18
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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

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Aug 26, 2018, 9:36:51 AM8/26/18
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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

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Aug 26, 2018, 7:09:46 PM8/26/18
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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

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Aug 26, 2018, 7:21:40 PM8/26/18
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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

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Aug 28, 2018, 10:01:26 AM8/28/18
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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

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Aug 30, 2018, 5:07:56 AM8/30/18
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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

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Aug 31, 2018, 1:18:17 AM8/31/18
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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

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Aug 31, 2018, 3:30:02 AM8/31/18
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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

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Sep 2, 2018, 9:07:08 AM9/2/18
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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

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Sep 2, 2018, 9:51:32 AM9/2/18
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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

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Sep 2, 2018, 3:31:35 PM9/2/18
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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

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Sep 2, 2018, 10:17:23 PM9/2/18
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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

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Sep 3, 2018, 2:29:12 AM9/3/18
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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

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Sep 3, 2018, 4:19:14 AM9/3/18
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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

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Sep 18, 2018, 8:03:51 PM9/18/18
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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

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Oct 4, 2018, 10:04:06 AM10/4/18
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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

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Oct 6, 2018, 6:00:49 AM10/6/18
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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

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Nov 30, 2018, 5:52:42 PM11/30/18
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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

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Apr 17, 2019, 3:08:14 PM4/17/19
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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

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Apr 18, 2019, 5:52:08 PM4/18/19
to
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

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Apr 19, 2019, 1:56:21 PM4/19/19
to
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

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Apr 24, 2019, 10:10:13 AM4/24/19
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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

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Apr 24, 2019, 12:52:52 PM4/24/19
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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

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May 26, 2019, 3:32:18 AM5/26/19
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s.maddalen...@gmail.com

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Jun 4, 2019, 7:20:29 PM6/4/19
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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

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Jun 4, 2019, 9:16:14 PM6/4/19
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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

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Jun 5, 2019, 7:07:20 AM6/5/19
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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

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Jun 5, 2019, 11:02:50 AM6/5/19
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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


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alish...@gmail.com

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Jun 7, 2019, 12:01:05 AM6/7/19
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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

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Jun 7, 2019, 1:59:13 AM6/7/19
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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

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Jun 7, 2019, 2:10:58 AM6/7/19
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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

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Jun 7, 2019, 2:12:57 AM6/7/19
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They're fantastic additions for any crew aiming to build confidence especially early on in their careers.

alish...@gmail.com

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Jun 11, 2019, 6:09:24 PM6/11/19
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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

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Jun 11, 2019, 6:12:49 PM6/11/19