First Bow

I intend to scan in my plans, but for now you'll have to observe the results!

I'm building a roughly 16'-long aft-mast catamaran that comes apart into pieces no longer than 8', so it fits inside my van. It will eventually be amphibious using bicycle wheels.

My understanding is the front of the boat should curve up (out of the water preferably) so it cuts through waves first before trying to float on them. So, my boat curves up in the front (these are the side panels).

I also cut up the bulkhead pieces. Each float is only 9" wide. The bottom will be a slight V-shape. My original intention was to have a flat bottom, but from these folks' experience it appears a flat bottom contributed to a very rough ride. So I added a 2" deep V to the bottom. Doesn't seem to be adding much extra work; just a few simple cuts.

I stitched together the two front sides to form the leading edge of the bow. However, I put the ugly side on the outside. Oops. I need the zip tie heads on the outside so I ended up cutting them all off then putting them back in.

While the two sides were attached, I drilled out holes along the bottom for the bottom pieces to stitch into.

Now I'm lining up the rearmost bulkhead and drilling stitch holes. I drilled through one edge of the bulkhead and both sides at the same time.

Then I lined up the other side of the bulkhead, made some marks, and drilled the stitch holes.

They lined up! Except... the rearmost bulkhead has reinforcements because the next section of hull bolts to its face, and it is going to be glued on and clamped, rather than stitched. So, this was a partial waste of time. Oh well. I'll reuse this piece somewhere else in the hull where it will be stitched.

Looks like a bow! I even stitched on the bulkhead before realizing my mistake. I have a lot of really short zip ties.

Drilling the first inner bulkhead. Drilling through one end of the bulkhead and both sides of hull. Note I have to drill two sets of holes in the side for the zip tie to come and go.

Inner bulkhead all stitched up!

According to Wood Bending Handbook by WC Stevens & N Turner, on page 13, the approximate amount of bending a cold piece of wood can take is given by the formula R/S=50, where R is the radius of curvature and S the thickness. When hot, the fomula can be R/S=13. The bow curve from leading edge to full width at the first inner bulkhead is designed to be a little over 50. Even so, it's still giving me a lot of creaking when I try to force it to be the curve I want. So when I go to install the second bulkhead (which will make it form its curve), I am going to stick an electric heater inside the front triangle and let it heat up for a while. I'd leave it out in the sun, but it'd mostly be the outside heating up, and wood will compress but not stretch so it's the inside that needs to be warm.

I set the bottom in place. I'm going to push them down into place, trace the sides underneath, then take them off and cut it out with either my jigsaw or bandsaw.