Monday, July 16, 2007

New direction

After I finished my model of a lobsterboat-style hull, I decided that , although fully functional, the boat looked drab and uninteresting. Rather slab-sided, not curvaceous enough, so I started over on the design. By changing co-efficients in some calculations, I gave the bow more flare, gave the stern more tumblehome, and flattened the run of the hull bottom. I also added a double cockpit and a fully cambered deck of classic runabout style. Then I started on building a new model. Drawings can't full visualize the three-dimensional form and proportions of such an object.

Lobsterboats are traditionally built in the range of 28 to 38 feet. Since I didn't want to exceed 20', the proper proportions weren't quite achievable on the reduced scale. Classic runabouts seem to be attractive to everybody, and I am no exception. I went to a wooden boat show and was disappointed in the selection of runabouts shown. Most were rather slab-sided, simple shapes; not a Riva among them. With the experience I have in creating developable shapes, I thought I could create something interesting.

I wanted fuel efficiency which generally means long and narrow. Twenty feet is the maximum length that will fit in most garages. The width had to be adequate for two people to sit abreast comfortably in the cockpit; that requires about a five foot width at the waterline. The result is a L/B ratio of 4:1 which is a reasonable compromise.

I am now finishing the 1/5 scale model of this new design and am extremely pleased with the result. This is the curvaceous and well proportioned shape I was hoping for. I hope to post pictures and more details in the near future. I don't plan to finish this model completely; I want to leave the deck open so that the structural details can be visualized- a guide for the future full sized hull. I do want to paint the outside of the hull and make it watertight so that I can check the hull buoyancy and loading.

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