30 Knots Per Hour With 9 HP

 

A Motor Boat That Travels Thirty Knots an Hour With Nine Horse Power

In the effort to develop high speed with motor-boats, T. W. Holmes, in England, has produced the most remarkable craft that has yet been built, and obtained a speed of 30 knots, which exceeds that of Dixie, the fastest American boat, and Napier Major, the speediest English craft, by over 4 knots an hour. Moreover, Capt. Holmes is confident of developing even better results, though other naval architects are doubtful of his ability materially to improve his product.

The tendency in motor boating in the past few years is to utilize the skimming stone idea in the belief that in such light craft high speeds are best obtained by skimming over the surface of the water rather than attempting to cut through it The theory that the resistance of the water, when minimized in the highest degree, will permit better results than can be obtained by increasing horse power and driving a boat against the weight of water it displaces has been pretty generally accepted. For this reason the craft that have been built have developed a broad, flat stern with a sharp-pointed bow operating on the wedge principle. However, it has been found that the weight of the engines sinks the stern even in the flat-bottomed craft materially, and that when traveling at the best rate possible the draught is increased still further by suction. Capt. Holmes has endeavored to avoid this by abandoning the pointed bow and increasing the beam of his craft, lightening the weight of his engine at the same time, so that the small weight distributed over a larger surface will sink the craft into the water to the slightest possible depth. The craft he has produced is unique

The boat's extreme length is only 11 feet 6 inches, in direct opposition to the established principle that length of water line is one of the most important factors in developing speed. In explanation of this step, Capt. Holmes advances the idea that length is only important when a boat it cutting through the water, and is a negligible quality in a skimming craft. He has given his boat a beam of three feet in an effort to distribute the weight of his engine to produce the smallest displacement.

The first difficulty in the operation of his boat was in steering it, and to obviate this objection he employed two distinctly novel ideas. First, he tunneled the bottom of the craft from stem to stern, compelling the water to pass through this tunnel as the boat sped over it, and making deviation from a straight path very difficult. His trouble then was that the boat would run straight but could not be turned without almost stopping its progress, and to overcome this he put the rudder at the bow, swung over a central pivot, so that when he turned it diverted the current of water passing into the tunnel and rendered the boat, to all intents and purposes flat bottomed temporarily. By the simple turning of the rudder its dirigibility returned, and it could be absolutely controlled.

With these two factors satisfactorily taken care of, the development of high speed was sought, and it was found that a 9 horse power engine could drive his craft 30 knots an hour. This, exceeding all records for motor craft, proved the value of his invention, while the comparison between the power of his boat and the 200 horse power required to get 26 knots out of the Napier and the 160 horse power needed by the Dixie was even more striking than their relative speeds.

Capt. Holmes believes that by increasing his horse power he can materially improve his speed, and thinks he can get fifty miles an hour. To an extent naval architects can agree that he can, but they say that any great increase in horse power will mean a material increase in weight and the sinking of his craft to a depth that will render it absolutely on an equity with old motorboats if he employs too high-power a motor. Experience has shown that high-powered motors cannot be secured with light material, since the various parts of the machine are then not strong enough to withstand the strain, and either break down entirely or else get out of alignment, so that they are rendered useless when driven at full speed for any length of time whatever. The lightest weight that has been obtained with any degree of success has been a 100 horse power machine weighing 400 pounds, an advantage of four pounds per horse power. And even this has not proved capable of running for a stretch of longer than twenty minutes without some difficulty being experienced which has compelled a slackening of speed.

Whether or not Capt. Holmes can overcome these practical difficulties as he anticipates remains to be seen. He is confident that he can; others are skeptical. He, however, replies that they ridiculed his ideas before he demonstrated them successfully, and that they will be as mistaken when he works out the problems that now confront him.

[Transcribed from the New York Times, Aug. 19, 1906, Sect. III, p. 3. ]

{It could be argued that this boat by Holmes was the first breakthrough in power boats that pointed either toward the three-point hydroplane configurations or the tunnel hull configurations that dominate boat racing today. From the Holmes approach in design we go the the Levavasseur step hull design to the Hickman sea-sled to the Ventnor sponson-hulled boats to the hydroplanes of Jones, et. al. — GWC}

[Thanks to Greg Calkins for help in preparing this page]