Dec. 26, 1903.] 
FOREST AND STREAM. 
818 
Speed Launch Dolphin.— Plate 6. 
Speed Launch Express. — Plate 7. 
bert L. Bowden, a 22-footer for Mr. C. F. Holmes, a 15- 
iooter and two small boats for Mr. A. P. Loring, a .30ft. 
launch for Mr. A. H. Chase, of Providence, a 22ft. 
cruiser for Mr. A. A. Bennett, of Chicago, and a new 
one-design of five or six boats for Osterville, Mass. They 
have also an order for a 21-footer for Mr. Kenneth 
Stevenson, of Detroit, to race for the Country Club cup. 
Mr. E. A. Boardman reports that the i8-footer for Mr. 
J. W. Olmstead has been finished by Shiverick, of 
Kingston. The i8-footer for Mr. R. de B. Boardman is 
set up at Fenton's, Manchester, and a is-footer for Mr. 
C. K. Pevear has been laid down at the same shop. 
John B. Killeen. 
Gasolene Engines for Marine Pro- 
pulsion. 
Eead at the eleventh general meeting of the Society of Naval 
Architects and Marine Engineers, held in New Yjrk, Xov." 
19 and 20. 1903. 
BY D. H. COXj MEMBER. 
(Concluded from page 494.) 
The Dolphin, a small launch recently constructed, is 
a good example of the extreme development in this direc- 
tion. Her lines are reproduced in Plate No. 6, and are 
most interesting, as is also the photograph, Plate No. 12. 
of her under way at full speed. The particulars of this 
launch are: 
Length over all 25ft. oin. 
Greatest beam 4ft. oin. 
Power 7 H. P. 
R.P.M 720 
Speed 12 miles 
The engine is a two-cycle single cylinder, sin. by sin. 
The contour of hull in the fore-and-aft plane below water 
will be seen to be straight from the lowest point at the 
forefoot to the bottom of the transom aft, and the load 
water plane will be seen to be nearly triangular, the bow 
being the apex and the stern the base. The sections are 
also triangular below the waterline. The entire absence 
of broken water shown by this hull, either in the wake 
or alongside, when driven at the high speed, for its 
length, of 12 miles, is most remarkable, and the speed 
reached with the given power is also \vorthy of attention. 
It is stated that an extreme design not unlike thi? 
launch has been tried in some German torpedo vessels, 
and excellent speed results obtained, although as sea 
boats the type proved a failure. 
The Express, another fast launch, is also shown in a 
photograph, Plate No. 13, and her lines are reproduced, 
Plate No. 7. She will be seen to be an approximation 
toward the extreme tj^pe as shown in the Dolphin, but 
the designer, not wishing a freak but a boat that would 
ha'f^e great speed and be comfortable in Long Island 
Sound in any weather, modifie4 his lines to a consider- 
able extent and produced a not abnormal looking hull 
above the waterline at least, and a good handy boat for 
the conditions desired. Her particulars are: 
Length over all 27ft oin. 
Beam extreme 4ft. oin. 
Power rated 9 H. P. 
The motor is a four-cylinder four-cycle machine, and 
is said to develop about 10 H. P. The photograph shows 
the small wave disturbance caused by this hull also and 
lier satisfactory absence of squat. It will be noticed, 
however, that there is considerably more broken water 
alongside than in the case of the more extreme Dolphin 
now give the inclined water-lines of sailing vessels care- 
ful consideration, a fact that at one time was altogether 
neglected. That success has been met with is readily seen 
fi-om the photographs and data accompanying this paper, 
and the efifect so often seen in short launches driven at 
high speeds of the forefoot completely out of water and 
Dolphin, 12 Miles an Hour.— Plate Vl 
There are other launches buih or building of extreme 
type that would make interesting subjects of study it' 
ilieir lines were available, but inform?.tion of this sort i'; 
hard to obtain. The general trend of the speed launch 
design is to make the squat as little as possible by the 
lull waterlines aft, and then to secure a proper entrance 
at the plane of flotation when under way instead of at 
rest in the water, much in the same manner as designers 
A smother of foam under the bow is conspicuously abse-it 
L.'n fortunately, in many instances the actual power de 
veloped by a gasolene engine of given size and rating 
quite problematical, and hence it is hard to arrive at any 
accurate conclusion regarding the performance of a par- 
ticular launch, and from it to draw conclusions regard- 
ing the probable effect of enlarging one of these modeh 
to a si/:e suitable for, ss}-, torpedo-boat work. It would 
Express l| KiK>t« a^n How.— Pla^? "i^ 
