Planking the first float hull half

After numerous distractions and test starts, we finally started to make progress on real, live boat construction.  Here you see about 2 hours worth of progress on planking a half of one of the float hulls (haven't decided which one yet).  This is the bow end.  As you can see, it takes lots of screws to hold the planks in place while the glue sets.  The screws and ply pieces will be removed after the glue sets and replaced with screws through the bottom of the forms (exterior side of the hull), so the interior glassing can be completed.  Then additional reinforcing elements and the bulkheads will be installed.  By then, the hull half should hold its form pretty well so it can be removed from the form.  Of course, this is a trimaran, so I get to start all over again on the second float half at that point, and then we flip the form frame around and make two more half sections to complete the floats.  Then it is on to the main hull ...

I am using a water activated polyurethane adhesive (similar to Gorilla Glue) to join the foam core planks.  This makes the planking process easier - just spray the edges, apply poly glue, and clamp in place while it foams.  And it should sand about the same as the foam, which is important for fairing the hull surfaces.  The seam between planks only needs to be as strong as the foam since the glass fiber will handle the structural loads.  The core serves as a spacer between the glass/epoxy surfaces in this composite sandwich. This type of construction works just like an I-beam, with the skins in compression/tension, while the core resists shear stresses.

At the end of the weekend, I had hoped to finish planking the entire hull half.  Unfortunately, a heat wave arrived and the temperature in the boat house skyrocketed into the 100's.  I called it a day early on Saturday when the thermometer inside hit 111 F!  (It was in the 90's outside)  The foam didn't care, but I wimped out.  Sunday was much better (only hit 101 F inside, and then thunderstorms provided welcomed relief), so I was able to make some progress.  I completed about 75% of the planking, including replacing the screw and ply clamps with screws through the bottom of the frame battens.  I used 1-1/8" fine thread drywall screws which were the perfect length to get maximum hold on the foam without going all the way through.  In the photo you can see what it looked like at the end of the day.  There are still a few screw and ply clamps on the last couple of planks because the glue hadn't quite set yet.  In any case, I can almost see a boat hull in there if I tilt my head and squint!