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Re: Stitch and Glue kayak problems
By:Paul jacobson
Date: 3/6/1999, 8:40 pm
In Response To: Stitch and Glue kayak problems (Doug)

> Help! I have started a kayak from commercial plans that really suck. I
> would be glad to reveal who's by e-mail. But at the present time I would
> be glad to just get it to work.

> (1) I'm at the stage where you stitch the beast together and I have some
> concerns. Boat is 198" stem to stern and has a 22" beam also is
> only 11" deep at amidship(sides) Will this thing even float 200lbs?

You got this far and NOW you want to know if it will float? Ah well. Rest assured that most designs similar to this have a carrying capacity of about 500 pounds. I can't tell you exactly how much your boat will support without some detailed ideas of the hull shape. General rule I go with is to assume the boat is of uniform depth and diamond shaped -- that is, it is composed of a triangle facing front joined to another triangle facing back. I can do the math on the area of the triangles very easily the height of each triangle is half the length of the boat. Base of the triangle is the width of the boat. The formula for a single triangel is 1/2 of the base times the height, but since I'm dealing with 2 triangles here, that cancels out the `1/2' factor, so my final formula is the width of the boath times half the length. In this case that would be 22 times 99 ( roughly 100) so you would have 2200 square inches of hull. For every inch that the hull drops in the water you'll displace 2200 cubic inches. Many of the designs I've seen have a water line at a depth of 4 inches. with your boat that would leave 7 inches above water, and give you a displacement (roughly) of 8800 cubic inches of water.

Another way to look at this: Your boat will rest about 1/3 of a foot (4 inches) in the water. It is about 2 feet wide and about 16 feet long. Taking half the length (8 feet) as the height of one of my triangles, I get an area of 16 square feet for the hull. At a depth of 4 inches (1/3 of a foot) I get a displacement of 5 1/3 cubic feet. A cubic foot of water is somewhere over 60 pounds, so we are talking about a displacement of somewhere over 300 pounds when the draft (depth) is 4 inches. That means that loading the boat so that it sinks an inch will take about 75 pounds of boat, paddler, gear or ballast. If you want to load it so that you have just 4 inches above water (pretty heavily loaded, but still maneuverable in calm water), and you have 11 inch sides, then you can load it so that it draws 7 inches of water. 7 times 75 pounds is a bit over 500 pounds, and that is what I quoted at the beginning of this discussion.

> (2) How are the sides and the bottom supposed to go together? edge to
> edge- or bottom over sides and sanded back(my idea) or what? I have loosly
> wired it this way.

Edge to edge. You will cover the joint on the outside of the boat with a layer of fiberglass fabric -- probably a piece of fiberglass woven into a tape, with non-ravelling edges. On the inside of the boat you will apply a bead of thickened epoxy mixture which will harden to become a full-length reinforcement. This fills the sharp bevel formed at the meeting of the wood panels, and it is smoothed into a nice gentle curve. Before it sets up you'll cover this with another piece of fiberglass and some resin.

This creates what I would call a reinforced butt joint. The glass/resin serves to reinforce the joint.

Clark-Craft has a free building supplies price list (their catalog is $5 ask for the right one and save some money) Last time I checked, in the price list they have a blurb about stitch and glue construction, and some pictures. You can get info on the price list (and catalog) from their website: www.clarkcraft.com

> (3) How do you figure the angle to cut the sheer clamps at stem and stern?

As you assemble the parts the pieces start to come together. When they get close you cut them to whatever shape seems to fit right. It might be a good idea to leave a bit of extra wood, and then you can trim it later with a sharp plane, or some agressive sanding, to make the pieces fit smoothly. You may have to wire the thing, then unwire it to make your cuts, then wire it again to check the fit, then unwire it to correct things, then re wire it, etc. This is not a big deal. Just assume that re-doing some wires is a normal construction concept.

> (4) Does anybody know of a similar design that would show location of
> cockpit and bulkheads for a boat this size? I would greatly appreciate any
> comments and or help you guys might have for this prarie boy.

You might look at Chris Kulczycki's book ``The Kayak Shop''. Otherwise, I'd pick up the assembled hull and find where the balance point is. I'd put the cockpit there. The point where a hull banaces in air is not the same as the center point when it is afloat, but this is usually close enough to work with. Adjust your seating back and forth after you start paddling, and you'll find the proper seat location in a few minutes of trial and error. In a worst case situation you'll have to make the cockpit a bit bigger.

Before you put on the deck make sure your feet fit. Seriously. There seem to be a lot of comments about decks being too low for size 12 feet. It is a lot easier to make deck bulkheads that are a bit higher before you install the deck if you need to accomodate large feet.

Hope this helps.

Paul Jacobson

Messages In This Thread

Stitch and Glue kayak problems
Doug -- 3/6/1999, 3:56 pm
Re: Stitch and Glue kayak problems - shear clamp a
Grant Goltz - Squeedunk Kayaks -- 3/12/1999, 4:35 pm
Look @ SWIFTWOOD
Brian T. Cunningham -- 3/8/1999, 12:17 pm
Re: Stitch and Glue kayak problems
Nolan Penney -- 3/8/1999, 7:12 am
Re: Stitch and Glue kayak problems
Russo -- 3/7/1999, 9:32 pm
Re: Stitch and Glue kayak problems
Chris Kulczycki -- 3/7/1999, 11:46 am
Re: Stitch and Glue kayak problems
Don Beale -- 3/7/1999, 1:08 am
Re: Stitch and Glue kayak problems
Dean Taylor -- 3/7/1999, 12:17 am
Re: Stitch and Glue kayak problems
Paul jacobson -- 3/6/1999, 8:40 pm
Re: Stitch and Glue kayak problems
Stan Heeres -- 3/6/1999, 5:14 pm