Displacement. Length. Beam. Draught. Horse-power. Esmeralda 3,000 270 42 18.3 6,500 Impérieuse 7,390 315 62 26.0 10,180
The eddy-making resistance is greater or less, of course, as the form is blunted or finer, and there is less resistance with a blunt bow and finely formed after-body than were the two reversed. Our practical towing friends will be glad to know that Mr. Froude substantiates their oft-reiterated assertion that a log tows more easily butt-end foremost. In the Merkara, a merchant ship built by Mr. Denny, of 3,980 tons, 360 feet length, 37.2 feet breadth, and 16.25 feet draught, this resistance is, at all speeds, about eight per cent. of the surface friction, which at the maximum speed of thirteen knots, at which she was intended to be run, still formed nearly eighty per cent. of the whole resistance.
A very wonderful result of these experiments has been to show (in the words of Mr. Froude) “what an exceedingly small force, after all, is the resistance of a ship compared with the apparent magnitude of the phenomena involved. Scarcely anyone, I imagine, seeing the new frigate Shah (of 6,250 tons displacement) steaming at full speed (from sixteen to seventeen knots) would be inclined, at first sight, to credit what is nevertheless a fact, that the whole propulsive force necessary to produce that apparently tremendous effect is only 27 tons—in fact, less than one two-hundredth part of the weight of the vessel—and of this small propulsive force at least 15 tons, or more than one-half, is employed in overcoming surface friction simply.”
[Illustration: The Giovanni Bausan, of the Italian Navy. (From an instantaneous photograph.)]
Of course, very small vessels, as torpedo-boats, have been driven at very high speeds, but the power necessary is in enormous disproportion as compared with the above, a development in 135-foot torpedo boats of from 1,000 to 1,500 horse-power and more being not uncommon.
The acceptance of the results of Mr. Froude’s deductions has naturally led to an increase in the beam of fast ocean steamers; we find all the later-built to be much broadened, and there is a still increasing tendency in that direction. It is needless to say how much this means in many ways to the passenger.