3/8 Scale Model
(three foot long)
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Foam Kayak

In previous episodes I talked about boats of various types. After much research and experimentation I built one. (well sort of). I’m poor, live in an apartment (don’t have much room) so I built it cheap. I built it out of foam.
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Build the Hull.
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To build a foam boat you need some foam. I chose XPS rigid insulation board from Home Depot (Lowes and other places have it too). Since I live in the south the only thing available to me was the thin stuff. 1 inch thick (its available in different thickness up north)


$19.48
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I needed some glue ,

$4.97 /each (2oz)
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and some toothpicks

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to stick it all together.
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First thing...
The layout.
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Use a sharpie or something that will mark on foam.
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Determine how wide you are and make the bottom of the hull that wide PLUS, however wide you want the walls of the boat.
Let’s say you’re a skinny little dude and you butt in only eighteen inches wide. and you want the wall 3inches thick.
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18” + 3” + 3” = 24” wide.
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Draw the outline of the bottom of the hull on the foam board.
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Next step.
Cut it out. Here’s the good part. Almost anything will cut foam. You can use a butter knife if you have too, a razor knife or any kind of knife (if that all you have.), or a saw
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An electric saber saw works GREAT.

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OR
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...a hotwire.
The hotwire is better in that it’s quite, cheap to build, and doesn’t leave a lot of foam dust. YouTube has a bunch of homebuilt versions
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So cut... and you get this

Cut what I call the arrowheads (because of the shape).
Measure down a little bit from the end of the hull. ( I chose a foot) and make a mark perpendicular to the centerline.

Take a piece of paper, cardboard, (something) and trace it out...and make a pattern.

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Use that pattern and trace them on the two small pieces.

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Cut them out.
This is what you have.

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Mark ‘arcs’ along the side of the cut side of the big piece.
3” wide, as many as you can.

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Cut ‘em all out too.
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Take the little triangles and notch ‘em to accept the arcs in the following manner.
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Set a triangle on each end of the hull bottom like so...with ‘about’ an inch over lap on all sides.
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Take two arcs...set them on top of the little triangles, mark a notch, leaving about an inch overlap on the sides.
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Dampen one piece with a little bit of water...smear gorilla glue on the other..secure it in place with toothpicks. Clamp or set weights on them and let dry (24hrs works).
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When it’s done
from the bottom

 
and repeat.
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That takes care of the first sheet of foam. the boat is 8ft 8inches long..and 30 inches wide, with very little freeboard... ..so keep stacking. It might take another sheet of foam (or two or three), depends on how high you want it.
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Funny thing about foam,(I discovered) It’ll bend, (a little bit) without breaking. You can have the sides go straight up (or not) and the ends extend (or not).
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Keep cutting, stacking, pinning and glueing...
eventually you wind up with something like this

 
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Smooth the sides, inside and out.
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I used one of these, just about anything will do.

It’s a wallpaper removal tool. It works amazingly well. (a little messy) In not very much time the ridges are gone and the sides are smooth.
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That's as much as I have done now.
Stay tuned.
Covering the Foam to prevent it from being damaged and adding strength is
NEXT.