THE SPORT AFLOAT

THE SPORT A FLOAT

long Mr. Kaye Don will be taking out “Miss England II” for his attempt to raise the late Sir Henry Segrave’s record, which stands

at 98.7 m.p.h. While he is preparing for this attempt at Buenos Aires, Mr. Gar Wood, who has for so many years been the leading exponent of speed on the water, is making preparations at Miami to wrest the record from Britain. His boat, “Miss America IX” remains unchanged except that the two Packard engines have been supercharged. They previously developed 1,000 h.p. apiece, and it is understood that this has now been increased to 1,300 h.p.

In view of the great effect on export trade of these records, the competition is keener than ever before, but although Gar Wood has a wonderful experience of racing craft, there is no foreign engine which can touch the Rolls engines of “Miss England.”

“Miss America’s” previous speed was 94 m.p.h. and in view of the comparative horse powers of the two crafts it seems unlikely that it will be able to approach “Miss England,” as it is probable that she will exceed 108 m.p.h. However, it does not do to count one’s chickens, and we can only hope that all will be well, and wish Kaye Don and his helpers the best of luck in their attempt.

High Revs. and Reliability. Previous to the last two or three years there was current a fear of designing anything in the marine line to rev, at more than 1,500 or so, due of course to the

fact that the engine of any boat spends most of its life at practically full throttle. Nowadays there are few automobile engines manufactured that you can burst by prolonged high speed, and naturally marine designers have been quick to make a more efficient type of engine now that no sacrifices need be made in. reliability. The modern unit for inboard semi-displacement craft now has a maximum of about 4,000 revs. Yet a Du Wite runabout, piloted by two girls, successfully completed a no-trouble cruise from the St. Lawrence to New Orleans, and some very dirty weather was experienced down the Atlantic sea-board.

But while the designers of inboard engines have kept up-to-date with automobile practice, those responsible for the new outboard motors have had to break new ground on their own, owing to the importance of the power weight ratio. Thus the main development has ‘been in the twostroke type of unit, in which all the reciprocating valve gear of the four-stroke is eliminated. The majority of outboard engines are multi-cylindered and rev, at something between 4,500 and the 5,000 mark, yet even such high efficiency motors as the 1000 c.c. job produced by the Outboard Motors Corporation and which develops about 55 b.h.p., never appears to tire on full throttle. From extensive experience with this type of unit on a speed dinghy it would appear that the only trouble which might occur would be due to the lubricant” cracking ” when the engine reaches its maximum temperature, for two-strokes are exceedingly critical on lubri

cation, because any excess of oil in the crankcase will contaminate the fresh incoming charge, with consequent over-heating due to this new charge burning and not properly exploding, while on the other hand the results of under lubrication are painfully obvious and incidentally expensive. But now, as it were, we come to the moral of the story. For while both inboard and outboard designers have successfully managed to combine reliability with an engine which produces an extraordinarily good b.h.p. for its size, the latter with but few exceptions, have had no regard for fuel consumption figures, and now we have a state of affairs in which a 150 b.h.p. inboard has the same petrol consumption as a 45 b.h.p. outboard, while the oil consumption of the latter is about twenty times that of the inboard. This state of affairs only refers to the high revving, high efficiency class of outboard motor, the purely utility job being ignored for the moment, and here in all fairness I think I should mention two outstanding examples from the general rule,— namely the Sharland and the Watermota. The Sharland is, of course, a horizontally opposed O.H.V. fourstroke, with dry sump lubrication, and thus conforming more closely to the ideas of car, or rather motor-cycle design, has compatible fuel consumption figures. On

the other hand the Watermota is of the two-strokeclass, but is a single cylinder, and chiefly owing to the skilful design of the ports, piston crown, and cylinder head (which factors prevent much of the fresh incoming charge escaping through the exhaust ports), and to the fact that the petroil system is not relied upon solely as a means of lubrication, there being three pressure feeds to the various bearings, the consumption of petrol and oil is kept within reasonable limits. These two engines are both within the B or 350 c.c. class, and so if one wants to indulge in the delights of going as fast as possible, one must pay to the tune of 21 miles to a gallon of racing spirit and 10 miles to a gallon of oil. Admittedly, the majority of these engines were designed in America where the fuel prices are much lower than in this country, but people do not want to spend money needlessly be it ever so little, and to my mind if there is a market for the big outboard as it stands to-day, there is undoubtedly room for a high efficiency motor with good consumption figures. Might we not glean a few ideas from the aero engine designer’s note-book ? for the Rolls-Royce R type racing engine used in the successful Supermarine S6 seaplane had a power-weight ratio of 1/ lbs. per h.p. and there are only one or two outboards that approach this figure.—M.