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Technical Papers
Navy A.O.G.'s powered with Cleveland diesels

DURING THE WAR a fleet of 23 twin-screw tankers was built to the order of the Navy Department at shipyards of Seattle-Tacoma Shipbuilding Company, Tacoma, Washington, and Cargill, Inc., Savage, Minnesota, for gasoline and lube oil transportation in the Pacific.
These ships are high-powered for their size, have good turn of speed, HVa knots to be exact, and are equipped
with considerably more propulsion and auxiliary power than is customary with tankers of their tonnage. Thirteen of them are still in active naval service; and the remainder may be sold, some to Bolivia and other countries, some transferred to the U. S. Army, and some to private tankshipping companies.

One of a fleet of 23 A. O. G.-fype Navy o!l tankers powered by diesel engines made by the Cleveland Diesel Engine Division of General Motors. Most of these tankers have four 16-cylinder engines totaling 6400 aggregate brake horsepower.

A. O. G. means Auxiliary Oil and Gasoline vessel. All 23 of these A.O.G.'s use General Motors Cleveland diesel engines for power. Most of them have four l6-cylinder units of 6400 aggregate brake horsepower at the maker's
normal rating, but at 5920 maximum hp and 3960 normal horsepower according to the Nav)''s rating for this
Some tankers of the A.O.G. class have two 16 cylinder engines of 1600 bhp each, and others have two 8 cylinder
engines of 800 bhp, installed for auxiliary purposes. Each vessel has a single-cylinder auxiliary unit as well.
All engines are of the two-cycle type.
These tankers are beautifully proportioned, and in appearance resemble the latest large ocean-going tankers with raked bow and a squat large-diameter stack. They have a single well forward and a catwalk aft of the bridge-house.

Following are their dimensions and other particulars:

Displacement, loaded (average)
4,160 tons
Displacement, light
1,744 tons
Cargo capacity net
1,960 tons
Length, o. a
310' 9"
Length, b. p.
292' 0"
48' 3"
Draft, loaded
15' fwd & 16' aft
Draft, light
6' fwd & 9' 2" aft
Depth, m. d.
19' 9"
Speed, loaded
14% knots
Fuel capacity
355 tons
Cruising radius
6,000 nautical miles
Each of the four main General Motors diesels drives a 775 kw General Electric generator at 675 rpm, and these units furnish direct current for two pairs of propulsion motors, each pair being geared to one of the twin propeller shafts. Each electric motor develops 960 shp.
The four-bladed propellers are of 8.75' diameter by 7.875' pitch.
The tank cargo space is designed to carry lubricating oil and gasoline or other petroleum derivitives with no possi-bility of contamination of lube oil by the other cargo. Two lube oil tanks forward are completely surrounded by coffer dam and a separate pump room and piping system installed for discharging this cargo. This room is equipped with two electric motor drive centrifugal pumps with a capacity of 2100 gph. The cargo capacity in lube oil is 4400 gal-lons. Cargo capacity for gasoline or diesel oil is 660,000 gallons and this is handled by two electric motor drive centrifugal pumps located in a pump room aft, and having a capacity of 72,000 gph.

View looking aft from the bridge of one of the fleet of 23 A.O.G. ype Navy oil tankers powered by General Motors diesel engines.

Accommodation is provided for 118 officers and men, including gun crews. Food storage, refrigeration, fresh water, heating and ventilating and stores are on a more extensive scale than is required in commercial tankers.
Eight of these engines ( as installed in each of seven submarine tenders) would provide about as much power
as is fitted currently in the most powerful American-flag steam turbine tanker. At full load, the 12,800 hp Cleveland
diesel propulsion units, plus the power of a small auxiliary engine at sea, only consume about 45 tons per 24-hour day. This is considerably less than the 74 tons required at top speed by the Cimarron class of tankship that was built shortly before the war by the American oil industry in collaboration with the Navy Department and the Maritime Com-mission. This means that on a 12-day, full-power voyage of a large motor tanker the total saving in fuel consumption would be 348 tons, or 696 tons on a round trip, without including the saving due to the lower fuel consumption of diesel engines.