A 1,650 HORSE-POWER GASOLINE FIRE BOAT. 139 
In the 20-foot space used for the propelling machinery are two 220-horse-power six- 
cylinder air starting and reversing “Standard” motors, each driving a 48-inch diameter by 
42-inch pitch three-bladed wheel of “Case” outward thrust pattern. Back of each wheel is a 
bronze rudder of balanced type. This arrangement of wheels and rudders gives much better 
handling qualities in close places than are usually found in craft of these proportions and 
does away with one of the main objections to the use of these subchaser hulls for this purpose. 
A 4% K.W. “Standard” auxiliary air compressing and generating set furnishes air for 
handling the main engines, electricity for lights and motors, and for keeping charged two 75- 
ampere-hour 110-volt storage batteries. These, with the necessary switches and instruments 
and the two electric blowers, take all the available engine-room space not required by the 
main engines. 
Including a 2-horse-power electric fire-alarm siren, there are seven motors and a search- 
light, as well as the lighting system, to be supplied with current. The circuits and switches 
are so arranged that either battery or the generator can carry the full load, or it can be 
divided between the three. 
The gasoline supply (1,200 gallons) is carried in the compartment aft of the engine 
room, from which it is cut off by a watertight steel bulkhead; it is stored in three No. 12 
gauge copper tanks, 36 inches by 96 inches, from which it is forced to the motors by air 
pressure from the air storage tanks. All openings to tank space are protected by wire gauze 
screens. 
Each propelling and pump engine exhausts directly out through the side of the hull, the 
exhaust being cooled and muffled by direct introduction of circulating water discharge. 
On the forward and after decks are hose boxes each containing 1,000 feet of hose. A 
3-foot heavy iron rail extends around the main and pilot-house decks. All the steel decks are 
fitted with removable wooden gratings. Heavy iron chocks and double bollards are fitted to 
each quarter of the steel trunk house. 
While the contract specifications of the pumping units called for a delivery (for each 
unit) of 1,250 gallons per minute at 150 pounds pressure and 1,100 gallons at 250 pounds, 
the tests at the builders’ factory showed nearly 1,500 gallons at the lower pressure and 1,200 
gallons at the higher. Tests at lower pressure gave a capacity of 1,750 gallons at 100 
pounds, making a total of 7,000 gallons for the four pumps. 
A special feature of this pump installation is that no compounding of the pumps is 
requited to deliver the high pressure—250 pounds. The entire range of pressures is obtained 
by varying the speed of the engines. 
These motors respond as readily to the throttle as a steam engine, and changes of speed 
from 1,000 to 1,500 revolutions produce all the range of pressure required. 
The engines at 1,500 revolutions run very smoothly and develop 300 horse-power, with 
a gasoline consumption of less than 0.66 pound of gasoline per horse-power hour. 
The position of the propelling engines was so near amidships that it necessitated placing 
the pumping machinery further forward than was desirable for proper trim. To correct this 
about 10 tons of iron ballast were stored in the after end of the engine-room bilge. 
The running trim is 7 feet draught forward and 6 feet 6 inches aft. 
Some apprehension was felt that there would be an excessive list from the nozzle re- 
action when discharging full capacity directly abeam, but tests made showed only 5 to 6 de- 
grees list under this condition. 
Preliminary runs have developed a speed of 15 miles, with engines making 450 turns. 
