Re: [Paddlewise] skeg ups

John Winters wrote:
> 
> ...<big snip>...
>
> An interesting aspect of skegs comes from their location. Both skegs and
> rudders generate lift to offset leeway. A skeg mounted well forward would
> work in much the same way as a centerboard on a sail boat producing a net
> increase in efficiency when paddling in conditions that produce leeway. A
> rather neat aspect deriving (possibly)  from a more amidships location comes
> in the form of both reducing leeway and weathercocking that, depending upon
> the shape of the hull, may not inhibit maneuverability.
> ...

Very interesting points. I wish we had more information regarding the
effectiveness of skegs (and various hull shapes) in reducing leeway, and
the implications for efficiency. This may or may not be important for
sea kayaks. In principle it seems as though it may be important, but
when paddling with others I have not noticed any obvious changes in
relative speed among boats with various designs (some with skegs) when
encountering conditions that produce leeway. I suspect that this is the
sort of thing that could only be detected with very carefully controlled
experiments, which is another way of stating that the effects are not
large. But maybe I would be surprised. 

One major difference between skegs and rudders that I have not seen
mentioned (in this recent discussion) is the tendency for rudders to
lift free in steep seas. I suppose that this is also something that can
be attributed to poor design, since it is a function of rudder
placement. This can be avoided by mounting the rudder under the hull,
and yes (in anticipation of the standard reaction) it *is* possible to
mount a *retractable* rudder under the hull. I recently saw one such
design that fully retracts. In addition to avoiding "lift out" and
surface piercing effects, I was told by the designer that there is
another advantage to this type of rudder. He claims that a foil-shaped
rudder can create lift more efficiently if it is in line with the boat's
keel. The standard stern-mounted rudder does not pivot about its center,
but instead swings out to the side. Does this really make a difference? 

Of course there is a simpler path. 

"Clean hands, Clean heart, Clean stern" (and clean keel)

Dan Hagen
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