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Re: skin on frame
By:Mike Allen
Date: 6/10/1999, 2:01 pm
In Response To: skin on frame (Kelly Trehearne)

I don't have the article in front of me and I am not building this kayak so I can't answer your specific questions but:

I consider Robert Morris's account of how to design/build a skin kayak the premier article I have ever read. It shows how the kayak sort of designs itself as you build. I look at his article as a description of a process rather than a direct prescription. So from this approach I'll attempt to answer some of your queries.

> 1)gunwale length is listed at 10 feet but in the article there is
> reference to a "centre mark" at 54 inches from the bow... Does
> that mean 54" along the length of the 3x1, or along the 'keel line'
> once the gunwales have been 'bowed'? Is the 10 footer cut to a length of 9
> feet or left at 10? What is the overall length of the completed kayak, as
> built per the article?

My guess is that the gunwales are 10 feet long before bending, but the important question of ctr mark will come more from the shape of the curved gunwales you bend than from anything else. Others can be more specific than I, but if the gunwale shape is symmetrical and you sort of intend a symmetrical boat, I would guess the c/l will be in the centre real dimension(guess at 58"- meaning boat is 9'8" long after gunwale curved). However, if I remember the kayak, it is quite distictly fish form, meaning that its true ctr of grav. or bouyancy is farther forward, so the placement at 54" true length from the front does not seem unreasonable. But the main point is that it depends - depends on the shape you choose - this the cool part - it can depend on how the gunwales bend - or how you rocker them - I think that I could play with the gunwales for hours. But I would strongly recommend making a simple simple simple scale model of the important parts.

> 2)Once the overall length is determined, how much longer will the keelson
> and hull stringers be than the bow to stern length? I was planning on
> ripping the gunwales, keelson, and stringers from a single plank, and so I
> want to ensure that I get a plank that will be long enough! The article
> lists a 12 foot length for the keelson/stringers - seems rather long...

My guess is that if the gunwales were 10' then the keelson would not be much more say 10'1 or 2

> 3)What is the reason for the 3/4" spacer in front of the
> backrest/deckbeam?

> 4)on page 42 it says 'position the last deck beam between the masik and
> footbrace...', yet there is no mention,nor photo, of this last deck beam.
> Is it needed, or is it a 'phantom' deckbeam??

I would put one in - the deck is important

> 5)the 'depth to sheer' is listed at around six inches, but in the photos
> it appears to be much greater...

My guess he means below the gunwale - so 6" + 3" + 4" = 13" high at the highest - seems reasonable

> Many thanks for any and all help, Kelly

try also link below - you'll see some of his posts.

Basically enjoy the process and allow it to be involved in determining the design. Have fun and tell us how you're doing.

-mike

Messages In This Thread

skin on frame
Kelly Trehearne -- 6/10/1999, 11:52 am
Re: skin on frame
Mike Allen -- 6/10/1999, 2:01 pm
Better Answers
Mike Allen -- 6/11/1999, 4:56 pm
Re: Better Answers
Kelly T -- 6/12/1999, 10:19 am
Re: Better Answers
Mike Hanks -- 6/13/1999, 10:45 pm
Re: Better Answers
Kelly T -- 6/18/1999, 12:12 pm
Re: Better Answers
Mike Hanks -- 6/18/1999, 12:51 pm
Some more
mike allen -- 6/13/1999, 12:54 pm