Re: [Paddlewise] A Rudder Experience

Your snazzy note read......

>Now the GTS tracks extremely well so I left the
> rudder up and was able to hold direction with no problem, except 
that the
> occasional sweep was causing a slight strain on a not perfect 
rotator cuff.
> 
> I then decided to lower the rudder to ease any possible strain on 
my
> shoulder.  As soon as the rudder was down, the stern anchored 
slightly and
> the bow blew off.  This was easily corrected by a bit of rudder.  
However I
> immediately began falling behind Kris.  Added drag, I guess.  I 
re-raised
> the rudder and caught up to her again.  I repeated the experiment 
with the
> same results.
> 
> A bit later the wind died.  I lowered the rudder again and was able 
to keep
> up again.
> 
> Conclusion:  The rudder adds drag only if deflected.  Obvious, I 
guess, if
> you think about it.
> 
> Jerry
> 

Interesting observations Jerry. A conclusion we came to was that as 
a designer, you need to decide whether your kayak will be balanced 
with or without a rudder in side winds. One of our kayaks was quite 
balanced without, and then with the rudder deployed (as virtually all 
people paddle here in New Zealand) the bow would blow downwind. 
This is exacerbated by light loadings/paddlers or stern loadings. 

Consequently we now produce boats that weathercock without the 
rudder, but are balanced (or more balanced depending on the final 
tradeoff we choose) with the the rudder. The stronger the winds, the 
more of a problem it becomes, and we do live in a very windy part of 
the world here.

I concur that using a rudder to turn, or hold trim causes drag. 
Paddling an Olympic K1 with a speedo mounted shows it clearly. 
Small steering movements show an instant speed loss, even with the 
tiny K1 rudder. Major turns show a massive speed loss. A sea kayak 
rudder which is most often a pretty large and crude foil will show big 
losses as its angle of attack increases.

For all that however, we've found that for our paddling conditions, 
rudders are more energy efficient overall both in racing and touring. 
The extra effort used to sweep stroke or lean the kayak to turn can 
be put into paddling instead. There are definitely some conditions 
where the rudderless kayak is faster however.

I also found that during speed testing of our latest boat, not deploying 
the rudder gave me an extra 0.3 of a knot (7.3 rather than 7.0) 
sprinting, but at a steady 5 knots I couldn't detect the difference. Of 
course that was in flat water, and I wasn't using the rudder to turn 
unless inadvertently, so the drag does become considerable at speed 
even without deflection.

Cheers,

Glyn Dickson
Paddling Perfection New Zealand
Finest Quality Handcrafted Kayaks
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