Subject: Re: [baidarka] Back to skegs for a minute
From: Jeffrey Hatton (jdhat@msn.com)
Date: Sun Oct 21 2001 - 09:41:28 EDT
I believe the difference between a kayak with a skeg and a surf board is the
speed at which we go. The surf board lines up with the waive and paddles like
mad to catch the waive. By the time they start to steer and put pressure on
the skeg, they are up on a plane and the skeg has a lot of grip on the water.
The kayak on the other hand is moving much slower the skeg is one more surface
for the overtaking waive to push on.
I have done quite a bit of windsurfing and the skeg (fin) really is not
effective until the board is moving much faster than a kayak travels.
Additionally the windsufer moves over the board to remain balanced with the
aft foot driving off of the fin which is something we cannot begin to do in a
kayak. On a windsurfer, and I believe on a surf board, the center of effort
is always centered on the fin (unless one is trying to turn).
In the kayak, the center of effort is more or less centered at the cockpit
with the skeg significantly aft of this balance point. As long as the kayak
is traveling faster than the waives, it will be effective. If the situation
is reversed such is waives off of the stern quarter, the skeg is adding to the
surface of the kayak the waive can push on.
I think my analysis is correct based on my paddling and windsurfing
experience.
Jeff
----- Original Message -----
From: Brian Nystrom
Sent: Saturday, October 20, 2001 10:33 AM
Subject: Re: [baidarka] Back to skegs for a minute
Phil Ellis wrote:
> Brian,
>
> On the skeg thing, your point is well taken on the leecocking effect a skeg
> would have if the boat was ballanced in the first place, but wouldn't it
> also improve directional stability under way?
Yes, but the boat will still turn downwind.
> And wouldn't it tend to
> prevent broaching on a following wave?
I don't believe so based on my experience with the YouKnowWhatKapp. I have a
plastic boat with a retractable skeg and I found that under certain following
sea conditions, I'm better off with the skeg up.
> Isn't that what the skegs are for on surfboards?
Possibly, but it's really an apples to oranges comparison. Surfers can move
around on the board to change their c/g, etc. at will, thus altering the
handling of the board. Kayakers can't. Consider also that a surfboard without
skegs has no keel; a kayak does. There is also nothing to anchor the bow of a
surfboard to the water. The narrow bow of a kayak serves as somewhat of a
forward skeg. Last, but not least, a surfboard is a planing hull. Except when
surfing, a kayak isn't.
> H.C. Petersen notes (Skinboats of Greenland, pp.68-69) that experiments with
> skegs (aka, steering fins) began in 1867 and that after the idea was
> described in an 1884 magazine article by Lars Moller, their use became
> widespread. Petersen says that the skegs were used to prevent the boat from
> suddenly veering as the hunter was about to throw his harpoon, but doesn't
> specify what the cause would be. It might be significant that this would
> also have been around the time that rifle hunting from kayaks became
> popular, and the magazine article mentioned above also described the rifle
> holster and shooting screen.
I believe this is referring to them traveling forward in a straight line. The
need for a skeg would obviously vary with the boat and the wind/water
conditions. If you're traveling upwind in a boat that weathercocks, no skeg
would be necessary.
Without reading the book, I really can't comment further. I have a copy on the
way from Greenland. When it gets here, I'll check it out.
> Anyway, I'm curious about how they work and how much drag the lines produce,
> and so on, and I can probably build one in less than an hour, so why not?
It certainly can't hurt to try it. If nothing else, it would be an interesting
experiment. I'm not trying to discourage you; I'm just offering some impirical
data.
> Somebody at the Delmarva had a strap-on rubber skeg (not sure I'd even tell
> people I had something like that), but I didn't get a chance to try it out.
Sounds kinky.
> Don't know where they got it.
Kayak_kinks.com perhaps? ;-)
> I also have part of an old photo from
> Skinboats in Greenland that shows a whole rack of West Greenland kayaks and
> they all have skegs. I'll post it for the curious.
I think I've seen the same photo.
> On the other hand, Harvey Golden and John Brand have both built boats
> similar to mine, and neither one of them mentions the wind and wave problem,
> so maybe it's just me.
Well, every skin boat is unique. No matter how carefully you follow a design,
there will always be some variation. I've also found that the weight of the
paddler makes a HUGE difference in many boats, SOF or otherwise.
--Regards
Brian
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