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From: John Winters <jdwinters_at_eastlink.ca> subject: [Paddlewise] weather cocking and racing Date: Fri, 29 Dec 2006 10:18:26 -0400 · This archive was generated by hypermail 2.4.0 : Thu Aug 21 2025 - 16:33:43 PDT

Avner wrote:
SNIP
> Only moving forward by 5-10cm (2-4 Inch), will of course lengthen the 
> stroke
> within its most efficient portion. But also will increase the weather
> cocking.
> Adding weight to the stern, should compensate for it.
> Still I am afraid that this extra weight, will slow me down, because more 
> of
> the kayak in the water, means more friction.
> What do you think?.

Not sure why moving the seat forward would change the stroke so I can't 
comment.

As for adding weight it would help to know if you are currently paddling at 
or close to the designed displacement for the boat. If not then you may want 
to consider a boat designed for your weight. I have no familiarity with the 
Cape Ann so can't comment on what will happen to its lateral area with more 
weight. Most boats require a lot of weight before a significant effect 
materializes. You can find out by asking the designer how much weight it 
takes to achieve a useful increase in draft. Of course, adding weight also 
increases wave making resistance.

Since weather cocking results from the effect of two forces (normal 
resistance acting from forward and leeway acting from the side) that produce 
a turning moment around the center of gravity you have two approaches - 
reduce leeway or counteract the turning moment forward with a turning moment 
aft. Increasing draft reduces leeway but probably not as effectively as a 
small fin (fixed or retractable like a sailboat's centerboard) that can even 
provide some lift. You can make a metal fin of sheet metal folded to have 
flange and tape it to the bottom to find the ideal location and size, then 
make a permanent fin once you have determined the size etc. (You can also do 
the same thing with a metal skeg to determine the best location and size.)

The other approach (skeg or rudder) is more common. Skegs are the simplest 
and probably the cheapest. You may even consider a fixed skeg for the sake 
of simplicity. The problem with a skeg or rudder is that neither reduces 
leeway so the boat still will travel farther than if it made no leeway or if 
you steer to compensate for leeway, the boat tracks at an angle through the 
water which also increases resistance. There is some interesting research on 
this (T.Tanner, Royal Institute of Naval Architects Transactions, 1960) and 
a good summary in Marchaj's "Sailing Theory and Practice".

Sprint racing kayaks use rudders because of the very problem Avner 
encountered. Controlling the boat with a rudder is more efficient than 
controlling it with the stroke. Many people look at this strictly from the 
standpoint of friction but the issue is one of net efficiency and the rudder 
achieves greater net efficiency.  Of course, sprint racers do not encounter 
the  extreme conditions of open water racers so a new boat or the fin option 
may make more sense.

There are many who swear by the "no appendage" philosophy but the proof is 
in the winning and if an appendage can do it, why fight physics.:-)
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