building a raft on $75

[Captain Mark]

Hi, I have entered a group into a local charity raft race, and we must design and build our own raft using only hand tools and $75 worth of materials.
It must hold three adults and hold together long enough to win three race heats.
Any ideas?

Cheers

[gonzo]

5gal (20 l) buckets end to end duct taped together. Make two sponsons and tie them together.

[mackid068]

Sounds pretty good! Duct tape is pretty strong. As the old adage goes: "If you can't fix it with duct tape, it's broken."

[yokebutt]

Mark,

I've seen inflatable mattresses at wal-mart for $1.99.

Yoke.

[marshmat]

I like the bucket idea, ya. A bit of duct tape (OK, a lot) and a few buckets (empty, and with the lids on) might work. Maybe tape a few old garage-sale reclining lawnchairs between them for a deck?

Or take up Yoke's point and duct-tape a dozen air mattresses together. Cheap, and so crazy it just might work.

[mackid068]

Well, if you have any sort of leftover house insulation or some foam, put that in the buckets for extra buoyancy. If a guy can sail a catamaran made of beer cans across the pacific, you can do this.

[Skippy]

If the raft needs to support a crew of three, hopefully you have a construction crew of at least two.

Buy six 4x8 sheets of plywood and 140+ft of furring strips.
Take four sheets, rip each one right down the middle, and scarf the halves together to make four 2x15 pieces.
Take two sheets and cut out of each sheet four identical 1x8 pieces shaped like the front half of a bullet.
Scarf the pieces together to make four 1x15 rounded slivers.
Screw/glue/nail furring edge-on all around the edges of all the slivers (one face only).
Screw/glue/nail the 2x15 pieces onto the furring to make two hulls.
Attach 2x4s across the tops to connect them.

You can improve on that a lot, but it's a starting point.

[mackid068]

Yeah, a catamaran could do nicely. But what about a plywood box with a scow hull?

\______| (simple enough, with sides, of course)

[Skippy]

Yes, the scow hulls are slower but even simpler. Just rip the pieces to shape & bang 'em together.

[mackid068]

Scows are a good idea, 'specially for rivers and places where you won't have to worry about comfort (like a barge)

[gonzo]

Hey guys: you are forgetting the budget is $75.00

[Skippy]

I'm thinking the cheapest ply he can find, pine furring, wood glue, etc. Actually, if he rips all the boards in 1/3s and makes 1'4" square sections, he'll have one strip leftover, enough for reinforcing the beams. But yes, I'm not positive how little that would cost.

[mackid068]

We ARE boaters, so budgets are constantly fluctuating.

But you could always falsify your budget...

[mackid068]

Well, if you have an old outboard motor and a table, there you go. Large table and an outboard makes a scow.

[Mark 42]

Originally Posted by mackid068

Well, if you have any sort of leftover house insulation or some foam, put that in the buckets for extra buoyancy.

If the buckets don't leak, the foam will reduce bouyancy. The air in the buckets will be pretty low density.
I'd be inclined to look for some tractor innertubes... might even get them free. Not as fast as a catamaran though.
If you can weld, some 55 gal. drums welded into a pair of pontoons.
Also, you can get cardboard concrete forms (tubes for making pilings) and smear them with lacquer inside and out.
If you can find some very large pipe (like for a culvert) you can cut notches and pinch the ends to make nice catamaran hulls too.

If you really want to go lightweight, build a frame and stretch blue tarp material over it. This page of cheap ideas is worth looking at:
http://www.friend.ly.net/~dadadata/index.html

http://www.friend.ly.net/~dadadata/boat/peero_plan.gif

You can also use chicken wire and cement.