The Best Form of Sailing Vessels

A Correspondent of the Scientific American, under the above caption, in the number of April 19th, thus writes: —Out of a great number of experiments with different sized models, the following was the most satisfactory: With a 20 inch model (2 inch beam) I tried the relative values of straight and curved floors, and I am constrained to believe that the latter is the best. With the straight floor and keel the model was drawn through still water 60 feet, by a seven pound iron sinker, the line passing over a horizontal staff in ten seconds. The sinker was then changed for a four pound lead, which required 14 seconds to accomplish the same result. The model was then cut down to convex curves, and the length divided into sevenths; forward three-sevenths shaped to a curve whose circle would be 600 inches in circumference, and aftermost four-sevenths, to the curve of a circle of 840 —nearly a parabolic curve; that is, in a ship 200 feet long the curve from forward to center of motion, and abaft that, would be respectively 1000 and 1400 feet radius. The model, when so altered, was drawn through the water by the seven pound sinker in nine seconds —a gain of one-tenth; and by the four pound sinker in 12 seconds — a gain of one-seventh; the buoyancy of this flotant was incomparably superior to the straight keel.

Now, we undertake to say, for the edification of this writer, and any others who may be inclined to squander their energies, that the farther they go in these kind of experiments, the less they will find they know about the best forms for sailing vessels. The only thing the writer has learned from his experiments is, that which every mechanic should know, whether he builds houses or ships, viz. that short vessels with round lines are more buoyant than long vessels with straight lines, for the simple reason that there was a greater proportion of breadth after the length was reduced, and, consequently, a greater proportion of buoyancy, inasmuch as the weight of the model was being reduced much faster by shortening than by reducing the breadth. Now, why all this trouble with models, when a strip of paper of half the size might have sufficed to show even greater results?

Colonel Beaufoy spent a long time in experimenting on blocks of wood, and after publishing a large quarto volume of over 400 pages, had only learned that he knew just nothing about the subject of which this writer has learned so much. We say that whatever is worth knowing is worth printing; but, really, the results of this writer's investigations are only worth printing for the purpose of exposing the very common error into which he has fallen. There are thousand varying conditions in which such experiments cannot enter; hence, they are only calculated to deceive and endanger human life. The subject of best models is of too much importance to be trifled with in this manner. Every change of model is an experiment; hence, every new vessel built, if the shape has been changed, is an experiment. In this sense, the writer is on the platform with the builders and masters of vessels — and experimenter on the models of vessels. But why this experiment to learn that which every school-boy may find in his school-books, viz., that wide vessels are more buoyant than narrow ones, inasmuch as the circle is the shortest boundary line containing an equal area of floatative surface.

The U.S. Nautical Magazine and Naval Journal Vol. IV (1855), p 108-109.

Transcribed by Lars Bruzelius

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