Re: [Paddlewise] rudder in/out of water

Doug wrote:
> However, it is entirely possible, and in my case,
>experiential, to have local wind-wave transposed upon the bigger sea. This
>sea state situation further exasperates broaching tendencies when it is at
>different angles to the larger swell, as some of the other techniques of
>edging and leaning can be inhibited if too dangerous or require countless
>hours of corrective action.

Why would edging and leaning techniques be too dangerous?  Aren't these the
very techniques that keep you upright?

>I would suggest a thick bungy cord
>haul-down that would be hands-free. Current Designs uses that type of
>system (there may be others, but Jerry has a CD boat so he can relate to
>the illustration). The rudder will lift up over the obstruction, then snap
>back down into the water as you glide along.

This mechanism does indeed work well.  I have asked companions to observe
the rudder as I deliberately went through kelp in different conditions and
the rudder snaps right back down.

> A well designed sea kayak generally has an ability to remain
>stable in a trough where the bow and stern are still supported yet retain
>the waterline.

I thought the problem was when the boat was on a crest, with the ends, and
the rudder, out of the water.


>I added 4 inches to my stock VC rudder, and find this works well with my
>Nordkapp which is slender toward the stern.

How important is this increase in length?  It seems to me that the Nordkapp
slender stern would cause the rudder to lift only rarely any way.  Did you
actually find that the VC rudder was too short in practice or did you
increase its length on general principles.

>I have limited the
>right and left "set" so as not to cause too much inefficiency in the water,
>and only use it when I absolutely need to.

Why not just rely on not applying too much rudder rather than mechanical
limits?

>We have a company on Vancouver
>Island that makes kayaks (two current models) called Extreme Interface.
>Their rudders retract into the hull. When in the down position, they never
>see "air time". They are a "drop-skeg-rudder-kind-of-thing" I guess.
>Apparently they work well, and I mention it to show you that designers are
>addressing the problems in some interesting ways.
>

Never heard of these boats.  Do they have a web site?



Matt wrote:
> It is only in steep following seas that it really becomes a problem.
>The length of the rudder, the length of the stern (longer can lift the
stern
>higher off the back of a wave) and how low the rudder is mounted all make a
>difference. ...... I'm sure anyone who get a kick surfing wind waves in
gales and boat
>wakes at the intersection of divergent and transverse waves, like I do, is
>familiar with this phenomenom. It's not just the rudder that comes out of
>the water its the narrow stern sections at the stern that on calmer days
>would help the kayak to track. Unfortunately it is just when the stern is
>out of the water that the kayak is on a position on the wave that most
>strongly promotes the tendency to broach.

I guess I haven't been in steep enough seas to notice this phenomenon.  The
rudder on my narrow sterned CD GTS has not come out of the water and I can
prevent a broach with small rudder corrections, sometimes with a bit of
additional stern rudder with the paddle.  Basically the same technique used
with my Mariner Express with full stern, except of course that the leans and
stern rudder are much more effective.

The lifting rudder that you cite for the Wilderness Systems XL may therefore
be a function of the total boat design rather than attributable to the
narrow stern alone.

Jerry

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