For this reason a sharp stem is put on a vessel, so that she can open a way for herself through the water like a wedge, and she is given what is called a fine run aft, so that her stern will not drag heavily.
Fig. 23.
Again, the larger the area of the boat’s greatest cross-section ([Fig. 23]), the more resistance that results and the slower she will travel. The area of the cross-section is diminished by making a boat of narrow beam, while the necessary displacement is obtained by increased length and depth.
Now, the difficulty arises that most of the qualities that ensure speed in a boat have a tendency to lessen her stability and even her lateral resistance. It follows that, while constructing a boat, a compromise has to be made between these three; and the problem as to how to produce the fittest craft becomes a very complicated one that has never been solved yet, and probably never will be.
Thus a long narrow shallow boat will run the fastest before the wind, but she will not turn to windward at all, and will capsize with great ease.
As it is recognized that beam is opposed to speed, it has been long the fashion in England to construct racing yachts extremely narrow and of great draught. Such craft do attain speed, but at the expense of all comfort, and when a heavy sea is running go through it instead of over it.
To come to the opposite extreme, we have the flat-bottomed very shallow and very beamy craft, with a deck plan not unlike a flat-iron—a veritable skimming-dish. Provided with a centre-board, such a boat is well adapted for shallow and sheltered waters. The centre-board can be raised while crossing a shoal, and the boat will then draw only as many inches as a deep-keel boat of her size would draw feet. She will be very fast in smooth water, but in rough water she will pound heavily into the seas, and, having no good hold of the water and little momentum, will lose her headway and soon prove dangerous.
For real comfort and seaworthiness—and some now maintain for racing purposes as well—a boat that is something between these two extremes answers the best; that is, a boat that is moderately beamy and has a moderate draught of water.