new speed/drag comparison

How about putting the same paddler in a number of different kayaks/surfskis,towing it up to maybe 15kph confirmed by gps,releasing the towrope and seeing how lonbg and how far it takes for tghe vessel to stop. Sure there are variables but it could be inbteresting
g

1 GPS makes no allowance for current or wind.
2 Boat run will depend on size of paddler, one boat may be better for bigger or smaller paddler.
3 Takes a bloody long time to make several runs of several boats.
4 Does not take into account the dynamic of a moving paddler and paddle induced boat movement.

It's already known that most top end skis are pretty close to each other already.
I think that you would find that the noise in you test may be greater than difference in the skis.......

But wouldn't hurt to try I suppose.

Valid comments but i would like to see a comparison not of the top end skis but a number of different types including plastic ones.
They do have a thing called lakes which to the best of my knowledge are current free and not all days are windy by the way.
as far as the dynamics sure I agree but is any test perfect?

as far as time is concerned.......you forget the fun factor.
But you do make valid pointss
B

I'd be interested to see this...

not a bad idea at all. we have champion lakes here in WA, a manmade lake for paddling with a rowing course, that would be ideal, but alas finding day without wind here in WA is challenging

Hmmm. Wind. Well this would be an estimation at best and not a definitive test......put in the disclaimer of course LOL.

Now for the technical part.

I'd also like to see how the resistance/effort/energy expent if you will varies with speed.

I use an endorfinn and notice above 6kph or so the effort required to cruise decreases. I always wonder what the maximum economical speed id if you well. I understand that in a resistance sport situation the speed vs resistance is more exponential than linear but I'd like to know at roughly what speed I am expending "too much" energy due to hull resistance I guess.
G

For sure, our six and a half meter boats are not as efficient at lower speeds than their shorter counterparts.

Every hull is designed to be efficient in the predicted speed range it will be operating in.

That's why it is pretty useless to put a beginner women and small men in a full size sea kayak.
More weight than need be and the hull is made to be best at a cruising speed in excess of what they are capable off.

It may also be a little bit of the reasoning behind the new Epic V8.

Now I got it.
The key phrase is efficientcy at the cruising speed I am capable of.
For now my endorfinn is the go. I do own a spirit race ski which requires less effort but still come to grips with the stability.......not a fan of onshore wind in Pt. Phillip Bay or the powerboat wakes at Patterson Lakes.
Thanks insight.
G

The information you'd get from the drag and glide test would be a sum of the ski's efficiency at each point on the curve of decreasing speeds. The data might be interesting but I'm not sure if it would tell us anything worthwhile at all. Like you said above, we're mainly interested in total drag with our weight at the certain speed that we race on flatwater. Total drag in rough water would be much more complicated to measure. Erik

Thanks for your responses. I have a better insight as to what speed to aim for and not try to exceed.
G

Trying to think of a not so technical way to measure drag while being towed at a certain speed.

How about a set of hanging scales (like they hang fish on) set-up between the tow craft and the ski, the drag would be measured in kg, would this be accurate enough?

Simplest way is to mount an accelerometer and paddle up to speed, stop paddling in each craft and compare the slope as it slows down.

I have an accelerometer app on my iPhone.

Or you could use one of these that I found last night whilst hunting for new paddles.

Cool device, I want one.


I downloaded the software and have been having a play with it with some provided files of some European paddler.
Don't know how much it is worth yet.
But it mounts to the craft, so is not paddle dependent, gives;

cadence
acceleration in three planes
speed

It can overlay graphs with each other and sync to a video and google earth for in depth paddling analysis.
Has cool things like relationships between variables like speed to cadence,

I want!

Polar makes a footpod which is also an accelerometer. I am trying to get a hold of them to see if there is a chance that will work for out purpose
g