[Paddlewise] Paul Caffyn's article

Hi all...

The other day someone posted a message about an article by Paul Caffyn on
the subject of rudders and skegs. Direct URL is

<www.watertribe.com/Magazine/May012000/May00Caffyn.asp>

He doesn't say anything new in this piece, basing it on experiences during
his Australian circumnavigation. Tasmanians might raise their eyebrows his
account of the origin of his rudder: in fact it was made in Tasmania by
Tony Gaiswinkler, who took measurements from an original by Laurie Ford,
the person who devised the idea of 270 deg retracting rudders in 1981 (and
receives no royalties from all those manufacturers of his idea).

There is an important point to remember about Paul's article: he is
describing a detachable fin, one that could be either on or off. In common
with many other on/off devices it had two effects: too much, or too little.

It was not a retractable fin with infinite adjustment between up or full
down that allows the boat to be trimmed to run straight of its own accord.
When such a boat is properly trimmed it needs no correcting strokes to hold
a heading. There is a world of difference between what Paul describes and
the fin systems in current use.

At one point in the article Paul quotes: [the rudder] 'not for steering,
but to trim. Sea kayaks are steered with the paddle, like all kayaks and
canoes.'

As the author of that I can give it to you in full: '2 The word 'steer' is
used here for convenience. The rudder is not for steering, but to trim. Sea
kayaks are steered with the paddle, like all kayaks and canoes.'

It's a footnote to a piece I wrote for the newsletter of the Victorian Sea
Kayak Club: Carter, P 'More on Fins', in Sewell, C (Ed) SeaTrek, 22,
February 1996, VSKC if you want the formal citation. It was based on a
paper I had written earlier: the current version is at
<users.senet.com.au/~pcarter/dirstab.html>.

I met, and paddled with, Paul on a couple of occasions before and during
the circumnavigation. One morning we briefly discussed kayak directional
stability. My understanding of the dynamics has increased greatly since
then: I sometimes wonder if Paul's has.

Paul may now steer with his rudder, but he took to rudders to fix a
directional stability problem, not to change direction.


Cheers,
Peter
pcarter_at_acslink.net.au
allegedly <www.acslink.net.au/~pcarter>
temporarily <users.senet.com.au/~pcarter>
34deg 55' 30" S 138deg 32' 4" E



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