1910 Harmsworth Trophy
The Challenger
Though it has now been determined that Great Britain will send over a full team to compete for the British International Trophy in August, the title of the challenger should be accorded to one boat only. That boat is Maple Leaf III, the property of E. Mackay Edgar, who sent through the British Motor Boat Club the first notification to the Motor Boat Club of America that there should be a race for the Trophy this year.
Maple Leaf III is being prepared by a rather novel process. She is a boat of very light construction, and as there are always risks of striking something when going fast, she is not being utilized at all for the tuning of the engine. Instead, a 50-footer, Maple Leaf II, has been built for use during the engine trials. Except for the extra 10 feet in length, one could scarcely distinguish between the hulls, for in profile they are identical and their lines are as much alike as the difference in length has permitted. The hull of Maple Leaf III was not put into the water until the end of June approached.
Maple Leaf II, however, was rushed through in time for dispatch to the Monaco carnival. In the Mediterranean she was unable to take part in a single race as she had no sooner been put afloat and her engine started up than one of the cylinders blew a portion of the head out. There had been no opportunity for running the engine on the test bench, and the boldness of taking the untried boat and engine to Monaco deserved a happier result. On her return to England the boat was sent to Southampton, and after the engine had been repaired, was taken through some progressive trials. The reverse gear had been taken out, and as the engine does not throttle down well, she is a rather tough proposition to handle. As a matter of fact, she had to be towed away to a clear space, because she is not capable of a lesser speed than 19 knots. On one of these occasions, when she had just been set running, the crankcase showed a flaw, which resulted in further delays. Of late she has been going exceedingly well, and at the time of writing, gives every promise of turning out a very speedy boat.
As far as possible, the trials are carried out in secret, and no reliable record of her speed has yet leaked out. The only clue which I have obtained was given in he course of conversation with Mr. Astell, the designer of the engine and responsible chief. I had remarked that there would probably be no opportunity for Maple Leaf II, the 50-footer, to meet the Duke of Westminster’s champion boat Ursula, which has a record of 36.7 knots—the speed of 37.9 knots officially returned at Monaco this year may be disregarded, the course being generally accepted as being short. In an unguarded moment Mr. Astell quickly rejoined that it was the greatest of pities that the two boats could not meet, because he knew he could beat Ursula. The manner of his reply left no doubt in my mind that he was speaking with knowledge, and one can deduce that Maple Leaf II, if she has not exceeded 35 knots in her trials, has only just missed it. As the engine has never yet gone all out, it seems to be sure as such a matter can be that the 50-footer is a 36-knot boat.
By skilful design he weight of Maple Leaf II, complete with crew, in running trim has been kept under three tons. Of the separate weights of hull and engine no notion has yet been gleaned. The hull is built without a keel, the framed being fitted to two long fore-and-aft girders which extend from stem to stern. These are very cleverly built up in the form of trussed girders, the top and bottom members being joined by struts, diagonally tied with wire. Although these girders are of light scantling, they are exceedingly strong and so stiff that although the planking of the hull is not five-sixteenths thick, there is not the slightest trace of whip when the boat is traveling fast. The engine is carried on two short bearers bolted to the struts of the girders, and has been found to be bedded as firmly as if it were on far bigger bearers of the ordinary type. The girders are used as keelsons, and the frames attached to them are quite light, being required only to carry the planking as if it formed a shell. Light stays are used between the top of the girders and the frames as additional support for the shell. The two boats are so much alike that the description of Maple Leaf II applies to the challenger in every respect except length. There is a considerable amount of flare forward and slight tumble home aft near the sloping box-transom. There is a slight overhang at the stem, where the draught of water is nil, and when the boat is at rest she appears to draw no more than three inches of water ten feet abaft the stem. What her immersed sections are cannot be guessed, but they are probably pretty flat.
In the engine one finds many novel features. As the outcome of the designer’s first experience with a big engine, it is a very smart piece of work. Piping has been practically chucked into the boat for two reasons, the first being that alterations are constantly being made to it as experience dictates, and the second that it will have to be altered slightly in the challenger. The twelve cylinders have a bore of 7 inches and a stroke of 8½ inches, are set six aside in V-fashion on the crankcase. They appear somewhat stubby owing to the fact that they are let onto the crankcase. Here one finds one of the most novel features of the design. The crankcase is composed of a bigger portion, in which the bearings are carried; and undertray and two end plates. In the upper casting are forms water spaces which, when the cylinders are let in, act as jackets for the lower portion of the trunks, with which joints are made. The crankcase is thus kept at a fairly low temperature, and the cylinders water-cooled throughout their whole length. It has not been forgotten that sea water has a disintegrating action on aluminum, and a 20-gallon fresh water tank is, therefore, carried under the floor boards forward. The water for the upper jackets is taken in the usual way from outside the boat. Lubrication is effected under pressure from a pump that distributes oil from the pipes to each main bearing, whence it flows through the crankshaft to the big-ends and pipes are provided to carry it up to the small-ends. The oil falls again into the base, and is drawn away from there and circulated through cold water before it is again used.
Each row of cylinders forms practically one engine in respect of carburetion and ignition. The carburetors are set on the outside of the engine and supply the mixture through forked induction pipes. Each cylinder has one large inlet valve, 3½ inches diameter, each about two inches across the face. The exhaust is carried straight outboard, the water from each cylinder jacket being turned straight into each exhaust pipe with the result that a considerable silencing effect is obtained. The two magnetos are mounted on a frame forward of the engine and, as with the carburetors, they each serve six cylinders a side. There are two water-pumps but only one oil pump. For starting compressed air is employed, but starting valves are fitted to only one set of six cylinders, the other set taking up the firing. There is, of course, only one camshaft, situated between the two rows of cylinders and operating the inlet valves through overhead rocking arms, which are drilled out for lightness, and the exhaust valves through push-rods. A control board is fitted on the port girder, thus leaving the after end of the engine unobstructed.
These details all apply to the challenger. She will be ready in good time, because the engine has simply to be lifted out of Maple Leaf II. The first wheel for the challenger is 3 feet in diameter and has a pitch of five feet. This may not prove exactly suited to it, but these figures afford a good indication of the size which is employed with this 400-hp. engine.
The Motor Boat of London, in its issue of June 9th, in referring to the Gold Challenge cup races, states that "it is possible that the whole of our B. I. Trophy team may go early to the States and try to capture the Gold Cup. Should that trophy be brought to this country, it would give a tremendous impetus to international racing in 1911."
(Transcribed from MotorBoat, June 25, 1910, pp. 38, 39.)
[Thanks to Greg Calkins for help in preparing this page --LF]
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