Devices for measuring boat check
Jake
behaviour of a small quantity of muddy water rolling up and down a
flat part of my stern deck. I noticed the way that during the drive, a
constant acceleration led to this dirty water flowing sternwards, then
during the recovery it flowed towards the bow, gently as the boat
gradually decelerated. Then as I was taking the catches, as I was
rowing sloppily for commuting purposes, and thinking of a million
other things, I noted that the patch of water would rapidly accelerate
bow-wards before the blades were properly engaged for the drive. This
means my boat was hitting the brakes. I then worked on covering my
blades faster (better timed, quicker catches) and stopped this water
from rolling towards me with such a rapid acceleration at the end of
the recovery, so was checking the boat less I think.
The usefulness of immediate feedback of this dirty water rolling back
and forth made me wonder if there had ever been simple devices on the
market that worked in this sort of way to gauge boat check. I know
that there's electronic devices containing accelerometers that could
do it. But I think a pingpong ball in a transparent banana shaped
chute might do the job much cheaper. I know coaches sometimes tape a
tube to the stern to create a water chute/ fountain, to indicate
changes in speed through the stroke while training but the extra drag
of this makes it unappealing for racing.
I also think an IPhone may contain a decent accelerometer from the
apps I have seen, but I don't know if they've done a waterproof
version yet. If they have, this kind of principle might make a useful
rowing app.
Or would such an indicator be indicating only part of a story that's
not quite so simple?
David McC
> While sculling home from work one evening last week, I noted the
> behaviour of a small quantity of muddy water rolling up and down a
> flat part of my stern deck. I noticed the way that during the drive, a
> constant acceleration led to this dirty water flowing sternwards, then
> during the recovery it flowed towards the bow, gently as the boat
> gradually decelerated. Then as I was taking the catches, as I was
> rowing sloppily for commuting purposes, and thinking of a million
> other things, I noted that the patch of water would rapidly accelerate
> bow-wards before the blades were properly engaged for the drive. This
> means my boat was hitting the brakes. I then worked on covering my
> blades faster (better timed, quicker catches) and stopped this water
> from rolling towards me with such a rapid acceleration at the end of
> the recovery, so was checking the boat less I think.
>
> The usefulness of immediate feedback of this dirty water rolling back
> and forth made me wonder if there had ever been simple devices on the
> market that worked in this sort of way to gauge boat check.
Haven't you just invented it, ... again?
Taniwha
Charles Carroll
Many scullers love the idea of the straw on the stern to indicate boat
check. As I understand it, the straw only really works at higher rates.
If you have access to a shell with a scupper in the bottom, you can use this
to tell you about how much you may be checking the boat. For example, with a
Maas 24 if you scull with the scupper open and can maintain a sucking sound
through the recovery, it is a good indication that you are minimizing boat
check. But again, this kind of vented valve only works at higher rates.
Active-tools makes a small device named ActiveTime that comes with a Check
Factor function. I highly recommend it.
Tony Andrews' app for the iPhone requires the separate purchase of a
waterproof case for the iPhone. Reports are that it is very good. But I
don't recall its having a Check Factor function. Tony, by the way, is a
consulting engineer for Nielsen Kellerman (NK).
NK recently has offered a wonderful device, Stroke Coach with surge. It has
an accelerometer and is super good for timing, rate and stroke count, but
does not come with a Check Factor function. I understand sales for the
device have been quite good. It is my hope that NK will build a next
generation device that will include a Check Factor function, among other
things.
Well, more than you wanted to know, eh?
Cordially,
Charles
"Jake" <frit...@googlemail.com> wrote in message
news:724a8749-a73e-4dcc...@q30g2000yqd.googlegroups.com...
Charles Carroll
just use the little bit of water in you cockpit. If it moves too rapidly
bowards, they say, you probably need to work on reducing check.
Jim Dwyer
Bend a small pipe or hose around your stern and tape it in place. One end
is in the water pointing towards the bow and
the other end sticks straight up in the air.
Have fun with it!
Jim
Now row and try to keep the water squirting out of the pipe at a constant
level.
"Jake" <frit...@googlemail.com> wrote in message
news:724a8749-a73e-4dcc...@q30g2000yqd.googlegroups.com...
Kit
Re. the pingpong ball idea: F1 driver Jackie Stewart used to advocate
driving with a pingpong ball in a saucer on your dashboard to help you
learn control around corners. So the idea may not be that far-fetched.
Kit
Carl Douglas
Mmmm. Aren't centripetal accelerations in F1 IRO 4G? In which case
Jackie's saucer would need to be hemispherical. Did anyone find a lot
of trashed celluloid around the track when he was the master?
;)
Carl
--
Carl Douglas Racing Shells -
Fine Small-Boats/AeRoWing Low-drag Riggers/Advanced Accessories
Write: Harris Boatyard, Laleham Reach, Chertsey KT16 8RP, UK
Find: http://tinyurl.com/2tqujf
Email: ca...@carldouglas.co.uk Tel: +44(0)1932-570946 Fax: -563682
URLs: www.carldouglas.co.uk (boats) & www.aerowing.co.uk (riggers)
Henry Law
> While sculling home from work one evening last week
Yeah, interesting discussion on acceleromters and such. But no
discussion on the most amazing thing of all: this guy goes to work, and
comes back _in his sculling boat_! That has got to be the coolest thing
in the work environment I've heard for years. (No pun intended).
Tell us more, Jake: where is home, where is work, where to you "park"
the boat when you get there, what do you do about anything you have to
carry (finding space for it, what if it gets wet), do you have to change
when you get to work (what do you work at), etc etc ... a hundred
fascinating questions.
(Of course everyone else in the group may know all about Jake; if so I
apologise for behing behind the curve).
--
Henry Law Manchester, England
Kit
> URLs: www.carldouglas.co.uk(boats) &www.aerowing.co.uk(riggers)
LOL. I think it was a recommendation to ordinary drivers in their road
cars, not F1 colleagues (who were IIRC more interested at the time in
the brightness of their fuel anyway).
I like the idea of simple tools like this, or the tube on the stern.
I'm sure there are other alternatives that don't involved $$$/£££.
Kit
Kit
In a similar vein, ISTR a story recently about a couple of St Paul's
boys who used to scull to/from school each day by 2x from the Richmond
area.
Kit
Tal Shalif (talos)
showing the boat acceleration/deceleration curve. I am using it
frequently to control boat roll during the stroke/recovery, but it
could also provide the kind of feedback you would like to improve on
the catch. The application works for me on my Nexus One, but may also
work on other mobile phones running Android 2.0 or above. Anyone
interested can download it from http://nargila.org/trac/robostroke.
Charles Carroll
Wow! An Android application for rowing that works on a Nexus One! I have
been waiting for this since I bought a Nexus One in March.
Have you read Tony Andrews' "Thoughts on Android?"
In brief Tony says that he could not write a Mobile Application for Android
for four reasons: Performance, Garbage Collection, Multi-tasking, and Device
fragmentation. You will have to read Tony's explanations for yourself. I
have almost no way of judging their accuracy. But I must say, having read
Tony's "Thoughts on Android," I did not expect to see a rowing application
for Android any time soon.
One question: how do you keep your Nexus One dry?
Charles Carroll
I downloaded robostroke this afternoon. It is installed and ready to use on
my Nexus One.
I am curious. Why did you decide not to list robostroke on Android Market?
One thing is for sure. I am not taking my Nexus One out on the water without
a waterproof case. Any recommendations? Do you know if the Nexus One will
fit into NK's waterproof case for the iPhone?
In the User Guide you mention that viewing the screen in daylight may be a
problem. I would imagine so, especially under a bright Sausalito sun. To
compound matters, I wear sunglasses with polarized lenses. While these
sunglasses reduce glare, they also have a tendency to make the Nexus One
screen nearly invisible. Do you have any suggestions?
At first glance, it seems like a nice app.
Cordially,
Charles
Roger
wrote:
Hey Jake,
You still at the RYA or have you found another close to the beach
place of work?
You can usually see the effect by looking at the very stern of the
boat, as you move towards the catch the boat accelerates, as you
arrive it starts to stop (??) until you get the blades in and drive. A
smooth recovery limits the acceleration and deceleration cycle which
helps keep the average speed higher than someone rushing down the
tracks for the next catch (Time on the slide is time wasted as the
saying goes in certain circles). I like the idea of the pingpong ball
in the cup althought the dink dink noise every stroke would begin to
wear after a while.
Mike De Petris
wrote:
> Active-tools makes a small device named ActiveTime that comes with a Check
> Factor function. I highly recommend it.
I have it since last October, it's a very good tool, is there anybody
around that can share his experience? I only use it in the single or
the "bigger sea single" and coastal rowing solo.
The reading is quite meaningful at higher rates, say over 30 spm, but
I still have to understand why I get counterintuictive reading at
lower rates, which check numbers should I aim for at say 24 spm?
Carl Douglas
Hi Mike -
What do you mean by "meaningful" and what was the "counterintuitive"
reading?
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: http://tinyurl.com/2tqujf
Mike De Petris
> Mike De Petris wrote:
> > On May 10, 12:47 am, "Charles Carroll" <charles_carr...@comcast.net>
> > wrote:
> >> Active-tools makes a small device named ActiveTime that comes with a Check
> >> Factor function. I highly recommend it.
>
> > I have it since last October, it's a very good tool, is there anybody
> > around that can share his experience? I only use it in the single or
> > the "bigger sea single" and coastal rowing solo.
>
> > The reading is quite meaningful at higher rates, say over 30 spm, but
> > I still have to understand why I get counterintuictive reading at
> > lower rates, which check numbers should I aim for at say 24 spm?
>
> Hi Mike -
>
> What do you mean by "meaningful" and what was the "counterintuitive"
> reading?
I mean, if I try, given a stroke rate, to have quicker catch, or
constant-speed recovery, or slow first part of recovery then
accelerate, or even slam forward then wait at the catch with blades to
the sky, I expect to read smaller or bigger numbers, but at low rates
I read the opposite!
Kit
wrote:
I am surprised that the performance on Android was such an issue for
Tony. There is no doubt that the iPhone offers a platform that is much
easier to get good performance on, given the single-tasking and use of
native-code applications. And one does need to approach performance on
Android which much more careful design. But there are plenty of
Android apps that integrate real-time processing of things like GPS
and accelerometer data so it should be possible.
Regarding fragmentation, there are plenty who would prefer a base-line
platform that applies over many phones, than tying the user to just
one type of phone. Android is certainly increasing in popularity. I
hope Tony doesn't miss the boat!
Kit
Charles Carroll
>> Check
>> Factor function. I highly recommend it.
> I have it since last October, it's a very good tool, is there anybody
> around that can share his experience? I only use it in the single or
> the "bigger sea single" and coastal rowing solo.
> The reading is quite meaningful at higher rates, say over 30 spm, but
> I still have to understand why I get counterintuictive reading at
> lower rates, which check numbers should I aim for at say 24 spm?
Mike,
See below:
Or in brief"
"Many thanks for your initial thoughts, and in answer to your queries:
">The first question is what do the numbers mean for boat check?
"The number is an average (over time) of the amount that you are
slowing the boat as you approach, and take, the catch. There is some
compensation built in for rate as at higher rates there is no way of
avoiding higher boat decelerations.
">The second question is what is a good number? What he is asking is what
numbers do the fastest, smoothest scullers produce? Is the low 20s a good
number? Or should he try for lower numbers? Could you give us a target
number?
"From what we have seen so far, good scullers achieve numbers in the
low 20s when paddling and numbers in the low to mid 40s when flat
out."
Mike De Petris
wrote:
> "The number is an average (over time) of the amount that you are
> slowing the boat as you approach, and take, the catch. There is some
> compensation built in for rate as at higher rates there is no way of
> avoiding higher boat decelerations.
>
> ">The second question is what is a good number? What he is asking is what
> numbers do the fastest, smoothest scullers produce? Is the low 20s a good
> number? Or should he try for lower numbers? Could you give us a target
> number?
>
> "From what we have seen so far, good scullers achieve numbers in the
> low 20s when paddling and numbers in the low to mid 40s when flat
> out."
thank you, I remember this post, now :-) and answers well to my
doubts, will make some more testing in the sea boat
Charles Carroll
> Tony. There is no doubt that the iPhone offers a platform that is much
> easier to get good performance on, given the single-tasking and use of
> native-code applications. And one does need to approach performance on
> Android which much more careful design. But there are plenty of
> Android apps that integrate real-time processing of things like GPS
> and accelerometer data so it should be possible.
Kit,
I downloaded and installed RoboStroke yesterday morning.
Tal has written a nice app, and it is certainly worth taking a look at. But
unhappily even with a Nexus One RoboStroke is unusable in bright sunlight.
It is just impossible to read the display.
Probably the fault should not be laid at Tal's door. While indoors the Nexus
One's display is stunning, outdoors is a different matter altogether. Peak
white brightness on the Nexus One is famously low and makes the Nexus One's
display nearly impossible to read in direct sunlight.
You could always take a Nexus One with you on the water and set RoboStroke
to record. That way you would acquire lots of information about an on water
session to review after you have come in off the water. But that's not
really how I want to use a rate meter/speedometer. I want a device that can
give me immediate feedback while I am sculling.
But in RoboStroke's favor, it can be said that it clearly shows you the
potential of Android. With an Android Phone with a better display it would
be a terrific application and quite a serviceable tool for scullers and
rowers.
As for Tony Andrews, he doesn't say what iteration of Android he used when
he did his consulting work on Android. Did he use 2.1? It would be
interesting to hear his thoughts on this, especially in light of Tal's
RoboStroke.
Cordially,
Charles
Ps When I entered RoboStroke in my Search Engine (Google), I was mildly
amused by the first hit. Tal chose an interesting name. I wonder if he has
to pay royalties to the other RoboStroke, which is a mechanical merkin with
luxurious ribs, etc. I can tell you, it brought a smile to my face. The
things you stumble upon when you search the net!
Jake
Hi Henry,
I don't consider rowing to work any more impractical than cycling in,
though the combination of factors that have to conspire to make it
possible are much harder to achieve for most people.
Home for me is Hamble near Southampton (SO31 4LB)
Work is at Sailing Today magazine (SO31 1ZL) www.sailingtoday.co.uk
With work being in a marina there are berth holders showers I use. I
take the sculls out of the boat and leave it upside down on the
riggers and hope kids don't climb on it while I'm at work. I keep
several full changes of clothes at work. The marina which is right
near work is sadly not accessible easily by sculling boat as the
pontoons are too high off the water, and getting out of the marina
through the electric gate with boat on shoulder or head would be next
to impossible. I have to keep the sculling boat on the public hard a
couple of hundred metres downstream of the office so it's useful that
it's a battered old Burgashell.
The route presents a challenging combination of conditions though,
which has led to me building and fitting a pair of stabilising
outriggers in foam/carbon/ epoxy (they are mounted just under the
riggers so well clear of the water). This means they are there in the
rough of Southampton Water to prevent a capsize if the worst comes to
the worst, but well above the water once into the Hamble river for
zero drag. The first part of the journey can be rough, and if it's low
water it's a longer journey as I have to go round Hamble spit. Then
there's the fact that it's a long carry each end at low water.
I've gone to quite a lot of trouble to put things into place to enable
rowing in, such as the floats, working out a safe place to keep it
etc. and quite a few days I need the car at work during the course of
the day so more often than not I end up driving in. Other times the
workload is too high to allow travel home before dark, even at this
time of year, so once again, it's the car. I think the culture of the
place I work (I am Editor of a yachting magazine) means that rowing in
is not frowned upon to the extent it might be if I worked in a bank or
something. It's barely noticed in fact. Many days our work itself
entails test sailing yachts, creating boat handling articles, testing
sailing gear and generally getting out on the water and hopefully a
reasonable time is had by all involved, so there's no great incentive
for anybody to give anybody else a hard time for getting to work in a
manner that helps them enjoy their job even more. However, if there's
been a few sacrifices required to enable me to row to work, it's
nothing compared to the decade of sustained effort I've put in to get
into the career of being a yachting journalist. There are plenty of
jobs I've had in the past where I'm sure some bitter middle manager
would have taken great pleasure in banning staff from rowing in for
some arbitrary reason. Still, those days are gone for me, for the time
being.
Still, rowing in is a good thing to do when I can manage it. Surely
I'm not completely alone in rowing to work though?
Back onto the original thrust of my posting, I've been thinking about
the 'pingpong ball in a chute' idea of a simple non electronic 'check
checker'. I think a better solution which would damp the movement a
bit more would be a u shaped clear plastic tube with coloured oil in
it half full. You could make it a complete circle so the oil doesn't
come out when the boat is turned upside down- which would be a bonus!
I'm going to knock something up and see if it works when I get the
time...
I like the idea of the squirting tube at the stern, but not the drag,
though the drag effect is largely psychological as the boundary layer
is pretty thick that far back. I'm after a solution that's a bit more
elegant for everyday use than the tube idea.
Tal Shalif (talos)
use an Aquapack waterproof which is not Nexus One specific. Screen
brightness is a problem with nexus one. It is possible to use it with
other android devices though. It needs Android version 1.5 or higher.
I row towards the end of the day, so I can usually see most details -
except for some of the background roll colours.
Tal
On 11 May, 03:51, "Charles Carroll" <charles_carr...@comcast.net>
wrote: