The Design

The hull on the modern Moth does very little. Unless the wind is low, the hull is totally out of the water. So other than aerodynamics and weight, the hull has very little impact on sailing. For this reason, you don’t need to have a highly specialized and evolved hull design. There are some important design considerations and you do spend some time with the hull in the water, but for the most part you can have whatever shape hull you want.

My hull design was based off of Phil S’s plywood moth design. The overall structure of the boat was reduced considerably from Phil’s designs to more closely resemble the newest generation of boats. I also wanted to put some pretty hard chines on the hull. Although a round hull is faster going through the water, a flatter hull with hard chines will plane faster and theoretically fly sooner.

Here are some pictures of the iterations of hulls shapes I created using cardboard. I tweaked each hull generation slightly until I got a hull that looked how I wanted it. I think the final result looks pretty good. After I completed my final design I discovered Doug Culnane’s moth Blog. Doug has been building moths for years and seems to know what he’s doing. His blog was nice enough to provide measurements at key points all over his newest boat. I started looking at these measurements and checking how close I was with my design. The verdict: close, really close, scary close, I-promise-I-did-not-copy-your-boat-design-Doug close. The reality is that Doug and I chose to do somewhat of a similar construction technique and that technique really lends itself to this boat shape. At least that’s the story I’m going with.

The only real difference the Mothball One will have from other modern designs will be the knuckle bow. This is a modification that I came up with which should have some good effects on sailing. The idea came from the latest generation of America’s Cup boats. If this design is used on the ultimate seahugger boats, then it should hopefully have some good effects on moth sailing when in seahugging mode, in theory. Also, it should improve the touchdown handling of the boat. The knuckle bow should impact the water all at once which will hopefully reduce the water entry speed and lessen the nose dive tendency... in theory.

Next Time – Construction Technique.