This is the part of the project where I got to cut up all that expensive HDPE into little pieces. So that I wouldn't ruin any material, I did quite a bit of layout work before I started cutting.

After I was pretty sure I had it right, I fabricated the seats and decks and got them installed. Note that I also fabricated all my wiring junction boxes out of the same plastic and welded the corners to make them watertight.

Since my plan included the purchase and installation of a brand new Honda 30 HP four-stroke outboard motor, I had to do considerable beefing up to the transom in order to properly support the additional horsepower for which the boat wasn't designed.

So I added a stiffener plate fabricated from 1/4" 6061-T6 aluminum sheet and sandwiched it between my transom pieces which are 3/4" HDPE sheet. Here's the stiffener before installation.

Transom stiffener in place....

I also braced the entire transom forward to the bottom of the hull (in the center) and to the gunwales (on each side) with angle iron to keep it from flexing under load. This works nicely as it doesn't flex at all and is quite tough!

Now came time for the fun part!