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Change the cross section of deck, not hull
By:Paul Jacobson
Date: 5/3/1999, 3:46 am
In Response To: g-expedition=same cross section as g? (craig appleyard)

> I have already painstakingly entered all the offsets for the g-mot forms.
> is the g-mot expedition single the same in height and beam and cockpit
> length as the 17' g-mot? i am concerned with getting my size 13s in there
> comfotably.

If I remember this correctly, and have nto confused you with someone else ( my apologies if I have) your original problem was with fitting into a Yare, a boat built from sheets of bent plywood. Now you are building a boat from wood strips. Different materials call for somewhat different techniques, and problems get slightly different solutions. With wood strip construction the solutions just might be easier than you imagine.

> is there any way that i could use 13" spacing between the forms to
> get a longer boat? and ad some (freeboard?) height to the fore deck.

You have one stated question and one implied one. I'm wondering if they are related. For that matter, I'm wondering of they are really the right questions. If I read between the lines, I'd guess your real question should be: How do I modify the plans to get room for my feet? I'll try to cover all these bases.

Yes, with most designs you can increase the spacing to 13 inches, or even 14. Do it over the entire length of the boat and your boat will be about 8 percent longer with similar (but not identical) characteristics to the planned design. This should give a hull with greater carrying capacity (displacement) and a theoretically higher top speed. It will also be heavier, use more materials, and be harder to turn. If you are the same weight s the boat was designed for, it will float higher, potentially making it more susceptible to being blown around by strong winds, but also allowing it to float in shallow water without scapes.

If you are heavier than normal you may want the added length to compensate for your weight. changing the length, however does not necessarily change the size of the cockpit to make it fit you. For big feet you want added interior height, not necessarily a longer boat.

With woodstrip construction this kind of modification is pretty simple. You have a couple of choices on how to do it. Let's assume you already have the forms cut out and mounted on the strongback. You would strip the hull without any changes. When it came time to strip the deck you would lay a few loose strips of wood over the top of the forms. The loose strips sitting on the top are at the height that the deck will become when you get to making it. Now, using a ruler, yardstick, or tape measure you could actually measure how much interior height you had available.

If you don't like the space that is available, modify it. With big feet you you would probably want to raise the deck IN THAT AREA. So, find the forms in front and in back of where your toes will be, and raise the top of the forms an inch or 4 inches (how big are your feet?) by nailing or screwing a piece of scrap wood to the top of the forms. If your feet are closer to one form than the other, make the scrap wood on that form higher than on the form that is far from your feet.

The scrap you have added to the form becomes in effect a new profile, or cross section for the deck. Shape it so that it blends in with the genereral lines or the rest of the forms. You can do this freehand on a bandsaw, or cut a paper or cardboard template in the shape you want, and use that as a guide in creating the new top line for these forms.

If you just add these spacers to two forms your deck will look like there is a big bubble in that area. This could be interesting, kind of like the way the hoods on hot rods are scooped and sculpted to accomodate the bigger carburetors that are under them. If you don't want such a radical look, raise the tops on several more forms, working fore and aft from your foot area. Use loose strips pressed gently against the forms to give yourself an idea of what the final deck contours will be. You can staple them temporarily in place, step back and get a good look at the emerging shape of the deck before you glue anything together.

You probably dont need, or want, to do anything to the deck behind the cockpit, so leave those forms alone. Since you are not making any changes below the sheerline (the point where the deck joins the hull) the paddling characteristics should be exactly as planned. The small additional amount that the deck is raised should not be a factor in strong winds. I have no way to predict how it will affect water spraying into your face, or not, when waves break over the bow. Nor can I predict how it will affect your ability to roll the kayak. My guess is that neither will be noticeably affected.

> thanks for any suggestions

You are welcome. Hope this helps.

Paul Jacobson

Messages In This Thread

g-expedition=same cross section as g?
craig appleyard -- 5/2/1999, 1:05 pm
Re: g-expedition=same cross section as g?
Nick Schade - Guillemot Kayaks -- 5/3/1999, 10:08 am
Change the cross section of deck, not hull
Paul Jacobson -- 5/3/1999, 3:46 am