First, I build a mold.
Next, I join together my EPS sheets. My boat is 12 feet long, but my EPS sheets are 8 feet long. Therefore I butt my sheets together and bond them with expanding polyurethane foam.
I designed the hull in Hulls, a free program for designing hulls. I then transfered the hull and panel layouts into AutoCAD where I completed the more detailed design drawings. The panel layouts were plotted full sized, glued to 1/8″ masonite, and patterns were cut from the masonite. I traced the panels to the EPS sheets from the patterns.
I cut the hull panels using a sharp steak knife.
The side panels are attached to the mold and bonded with expanding foam.
Thickened epoxy is applied to the top edges of the side panels (which are actually the bottom edges since the hull is being built upside down) and the bottom panel is bonded to the side panels. The jugs of water are used to bend the bottom panel to shape. Drywall screws temporarily hold the bottom panel in place while the epoxy sets.
Once the epoxy sets I shape the hull with a Surform and sanding block. The bottom panel is trimmed flush with the side panels, and all edges are given a slight radius so the fiberglass will drape over the hull properly.
The photo below shows how much rocker the hull has.
I also added a bit of V to the bow and stern.
The hull is ready for fiberglass. I used 4 layers of 6 oz cloth on the bottom and 3 layers on the sides. Getting all of that cloth to drape properly over the hull took 2 days.
It took another day to wet out the cloth with epoxy.
Three hot coats were needed to fill out the weave and get a glossy finish for sanding. The hull was then flipped over and the mold was removed.
Here I am pouring some expanding foam into the bow.
Now I am ready to fiberglass the inside of the hull.