Boat Design

Model testing the Almaguin, part 1: The framework

Computer simulations are pretty good these days, but there's still a lot they can't do. And as nice as it would be to have my own full-scale prototype of every boat I draw, that's just not feasible- there's never enough space or money for that. Models, though, are inexpensive, don't take up much room, and are fun to build- and, if done carefully with the right mathematical backing, can offer a lot of insight into how the full-size boat will perform.

Boat Parameters

Here is a list of definitions for the various parameters used to describe boats.

As a general rule, parameters and ratios listed on the M. B. Marsh Design site are for the boat at its fully loaded design displacement, including full tanks, full crew, and typical cargo. The one exception is the light-ship displacement figure, which is (roughly) the weight of the fully fitted out, but unloaded, boat as it leaves the construction shed.


Why so few proas?

Proas- the original multihulls- are rather rare these days. Which is really quite a shame.

A proa, for the uninitiated, is a laterally asymmetrical multihull: one hull is smaller than the other. Proas, at least in the strict definition, are also double-ended, switching bow for stern in a manoeuvre called a "shunt" when ordinary sailboats would tack. There are, of course, proas that tack in the conventional manner, although these are more commonly called tacking outriggers.

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