The curves not so good

Tue 30 July 2013 by Cory Cross

When I examined the curves of the boat as I began assembling it, I realized something was amiss. The front curved inward far too tightly. When I drew the lines on paper I realized I had done it so tightly the side would have been concave!

So real designers use battens to create their dimensions. Below is me doing so. In order to get a decent-looking curve that's still thin enough for the fore-hull to nest in the aft-hull, I shortened the fore-hull by 6 inches, bring the total length of the fore-hull to 5' and the overall boat length to 12' 6".

I then took distances from the centerline along its length and adjusted my drawings.

Built forms, mounted aft hull

Sun 28 July 2013 by Cory Cross

When building a plywood stitch-and-glue boat, you don't need to build the boat on the traditional forms and strongback because the shape of the panels fully constrains the boat. However, since I have created my own plans, I don't have the shape of my panels. They could theoretically be designed …

Lines drawn, bulkheads cut

Sun 21 July 2013 by Cory Cross

I got impatient waiting for the Piccup Pram plans to arrive, so Saturday I went down to the library and read 20-odd issues of Boat Design Quarterly. BDQ has a collection of about 6 plans varying from "study plans" to full dimensions for different boats in each issue. A "study …

Change in plans

Tue 16 July 2013 by Cory Cross

Been scraping off the old epoxy and finally put new fillets in. But as I've been planning the mast and sail plan, I didn't like the designs that I came up with. The amas (side floats) would be plenty strong, but I don't know if the center sections would be …

Ruh-roh, screwed up the epoxy mix

Sun 30 June 2013 by Cory Cross

I went to add more fillets today and noticed yesterday's were still squishy. Ruh-roh. I haven't used this epoxy before and thought maybe the cool temperature just makes it take a long time (though unlikely). So I carefully made up another batch, added more fillets, and it set within a …

They aren't the prettiest fillets ever

Sat 29 June 2013 by Cory Cross

Okay, next time I'm going to start with the fillets at the bottom of the boat. Because when reaching down to the bottom I wiped my arm across the ones at the top. Yuck!

They aren't pretty, but they're hopefully functional.

Stitching the bottom in

Sat 22 June 2013 by Cory Cross

Complex curves are hard.

As the bow curves upward, the bottom pieces slope upward (downward in these pictures since it is upside-down) in a complex 3-dimensional curve. I started trimming the front to match the curve, and I couldn't get them to bend or line up worth a damn, so …

First Bow's Rear Bulkhead

Thu 20 June 2013 by Cory Cross

So I glued up the reinforcing pieces of 3/4" (so-called 1") thick, 1.7" inch wide pieces of pine to the inside of the rear bulkhead. There'll be 1/2" holes through this where I'll bolt 1/2" SS bolts through to lock the hulls together.

The day before …

First Bow

Wed 19 June 2013 by Cory Cross

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 …