These are made from swimming pool toys called "Wacky Noodles", also know as "Pool Noodles". I found them on sale for $1.29 each. Four were required. They are described as "Closed-cell polyethylene foam rods", "66 inches long." Some measure 60". Outside diameter about 2 1/2" with a 1/2" hole. NEW I recently discovered Wacky Noodles are being made in "giant size". Oversize Wacky Noodles. They are 5" diameter with a 1" hole, 66" long. That gives each one a buoyancy of 44.9 pounds (24.4 kilo) in fresh water vs. ~25 pounds for the smaller 2 1/2" noodles. It will take four noodles to do both sides of the Flapdoodle.
The calculated displacement is 25 pounds (11.34 kilo) for all four of them. A capsize would let my trolling motor battery sink, but the noodles are more than enough to prevent my trolling motor from sinking the Flapdoodle. Not great, but every bit helps. Later I will show how to increase this.
Begin by cutting the connectors from scrap wood. They are ~3" (7.62cm) long and about 1/2 x 3/4 inch (1.27 x 2cm). Not a thing critical here.
Make one for every hole in the gunwale you plan to tie them to. Drill the hole 1/2" (6.5mm) and sand the ends round. I did not bother to sand the sides, then dipped them in shellac.
I attached a line to a long thin wood scrap with tape and treaded it into 2 noodles. One end was tied to the gunwale at the stern, and the other trimmed to match a hole near the bow then tied. The noodles cut very easily with a razor cutter.
The line tied to the gunwale was replaced with a wood toggle later.
A cut was made in the noodle at middle of the boat, a line fed through the hole in the wood connector. Then the connector (shown in red) was inserted in the gap and tied to the gunwale. Use as many as you feel necessary.
If you want more buoyancy, two rows of noodles could be used:
The connector is more work though. Two dowels glued into holes in a small strip of plywood. Allow a slot for the lines that runs the length of the boat.
I discovered another noodle user here
