Re: [Paddlewise] Turns Easier When Loaded (was:RE: Baja Trip report and photos)

From: Matt Broze <mkayaks_at_oz.net>
Date: Wed, 16 Jan 2002 18:46:24 -0800
Mike wrote:
>>>>Matt, do you have the numbers for the GT for comparison?  Its extra beam
is often offered as a reason for its easier turning.  The wider midsection
is supposed to allow the keel to be lifted easier and aid in turning.
I've noticed a difference, but haven't seen anything like an objective
test.<<<<<<<<

GTS   22 sec. leaned  43 level
GT    14 sec. leaned  34 level (15 leaned with full rudder)
GT XL 17 sec. leaned  32 level (20 leaned with full rudder)

The GT was done in fresh water in April 93 (estimate 50 degrees) the GTS and
GT XL were done in salt water in (Sept. 99 and 01--estimate temp about 50
degrees). Salt to fresh water density differences tend to cancel out as the
kayak floats higher to compensate. However, there is about a 2.5% difference
for each 10 degrees of water temperature difference due to the greater
viscosity (stickiness) of colder water that I have to factor in if comparing
or analyzing the raw data.

The extra beam of the GT's certainly helps and (at least partly) for the
reason you heard. Also I might be able to lean the wider kayak more before
water would pour into an uncovered cockpit (which is the maximum I lean
during the test--if I can do that much without excessive risk of capsizing
given the cockpit bracing situation--because that way I can compare a kayak
even though I don't have a spraydeck to fit it. Given the same width cockpit
I could most likely lean the GT more because of the wider middle too.
Several other factors could be involved as well such as more rocker or
shallower angles at the keels but just the one proposed to you could account
for this difference. I noted it was windy the day I tested the GT (but not
the GT XL). Wave action might have sped up the GT's leaned turn a little bit
(and with a stiff tracking boat I'd do the test at an angle where the wind
might help me do less work rather than more--but I think without waves, in
general, a wind slows me down a bit especially with the level turns). The
wind might have slowed the level turn somewhat especially if I had to turn
the bow into it at any point during the 180. Even if I avoided that the
stern would be slowed when I was more sideways to the wind.
I get real tired of stiff tracking boats when faced with testing many of
them in a row through three 360 degree spins and three 180 degree turns with
each kayak one after the other. Probably the reason I didn't test the turn
with the rudder down with the GTS was that I didn't feel like putting my all
into another long hard (but slow) turn again right away (although sometimes
I don't get rudder down data because the rudder is broken or the pedals have
become jammed with sand on beach demo days). Sometimes I cheat a bit with
the real slow turning boats. I spin a 180 in place and multiply by two. I
always do a full 180 on all the "at speed" turns though. I also count
strokes on the spins but I have found that strokes can vary a whole lot more
than the time will when testing the same kayak repeatedly.

Matt Broze
http://www.marinerkayaks.com


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Received on Wed Jan 16 2002 - 18:42:11 PST

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