Lew Crenshaw: My most recent idea is to install the coaming the way
Feathercraft does its hatches. Sew a piece of nylon or neoprene the shape of
your coaming to the deck where the cockpit will be, install shock cord to its
inside edge and pull it up and over the lip of your coaming.
Ralph Hoehn: That would appear to be an excellent idea!!
I'm not sure whether it is better if the material comes up through the inner
diameter of the coaming and is pulled over the outside or vice versa.
Pouch uses such a system for the reach-through hatches, where the material
comes up through the inside. The main reason for this is that an integral
roll-top closure provides the water tight seal rather than a hatch cover --
the latter is provided only as a final security measure.
In theory I would favour having the rim material come up over the outside of
the coaming. That way the addition of the spray skirt would tend to reinforce
the grip on the coaming, rather than trying to pull the rim material off with
it as sometimes happens with seasocks that come off together with the spray
skirt, for example.
Not having tried it, I only wonder whether you can get the shock cord tight
enough to produce a fully reliable fit; the hatches are much smaller and are
circular (most modern coamings are not likely to be circular).
Perhaps a combination of this concept and Stefano's would be a useful way
forward.
Having played with Peter Chopelas's North Alaska Retrieval Kayak, I feel that
the leg of Stefano's "P", as well a generous outer diameter are important to
obtain a strong attachment for the spray skirt.
Lorenz Mayr (author of "The Book" :-) advocates a solution by Herbert Slanar
(one of the pioneers of the thirties -- and still going strong strong in the
fifties -- of folding greenland type kayaks, although adapted for white water
use). A brief synopsis:
1 - Make a flat left and right circle-section sleeve of deck material, its
inner circumference sewn to the inner circumference of the cockpit hole in
the deck material.
2 - Flat aluminium circle-sections can be pushed in from slots in the rear of
the coaming, meet at a seam at the front and have small overlapping tabs in
the rear, which stop them from slipping out or from slipping over each other.
(The sections must be true sections of a circle or they will not easily go
into the sleeves!)
This solution works well on the "Moell", originally designed by Herbert
Slanar and commercially produced by GESA, pictures of which can be admired on
Marian Gunkel's website. The latter reports that the arrangement works well,
providing a good seal and good security. Lorenz Mayr installed this on all of
his boats and is fully satisfied after using them in heavy white water for
almost fifty years.
In some of their singles Klepper, Pouch and, in an adapted solution
Feathercraft, have a reinforced inside rim of the deck material inserted in a
groove running around the inside of the coaming. This works well, but can be
a pain to assemble unless the fabric and the groove are well matched.
Subsequent tensioning of the deck holds the material and hence the coaming in
place. I doubt that it would be a pleasure to build at home though!
One solution that has intrigued me (but not yet enough to try it) would be to
adapt a particular Greenland practice: The cockpit rim has a ledge around the
bottom of the inner edge, into which (short, well rounded) pegs are driven
more or less vertically. The deck material receives small holes to correspond
to these pegs. A special tool makes hooking the deck over the pegs easier.
In an adaptation to folding kayak construction, a bungee cord stitched at
intervals to the rim of the deck material and hooked over the pegs could be
substituted. I doubt that this would be any trickier during assembly than the
solution where the material has to be inserted in the groove.
However, at the end Lew's solution seems to hold the most promise in my view.
I look forward to trying it or hearing more about its implementation.
Happy New Year and best regards,
Ralph
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