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HE Onon- daga and | | \ ch i Tahoma. The arrangement is generally simi- Boe Neale Het | lar for the Al- gonquin and sisterships eri making rescues under the most ad- verse conditions. Reference has al- ready been made to their ice-breaking qualifications. Sturdiness is an out- standing feature of their construction, and the frames are unusually closely spaced. They are of flush upper deck de- sign, straight raked stem and the con- ventional cylindrical overhung stern. In addition to the upper deck there is also a continuous main deck throughout, aS well as an orlop or berth deck, which extends from the stem to the forward bulkhead of the boiler room. The boiler room is located almost exactly amidships and the center of the stack where it emerges through the deck house is only a few inches aft of amidships. The machinery space set off by watertight bulkheads is di- rectly aft of the boiler room. Quarters for the crew and petty officers are located on the main and berth decks forward. The ward room — is located aft on the main deck. The power plants of all of these vessels incorporate the latest marine engineering developments and are de- signed and constructed for dependa- bility and efficiency. Since these power plants are quite different in detail, they will be described separately. Propelling Machinery, Onondaga In the OnonpdsAGA and the TAHOMA the main propelling machinery consists of one marine steam turbine connected to a single propeller through double reduction gears. With 300 pounds per square inch steam pressure, 200 de- grees superheat and 27% inches of vacuum, the rating of this turbine is 1500 horsepower at 7500 revolutions per minute. The turbine speed is re- duced through the gearing to a normal maximum propeller speed of 140 revo- lutions per minute. The speed of the vessels is 13 knots. The main pro- pelling machinery for both of these two vesscls was supplied by the De Laval Steam Turbine Co. Steam is generated on these two ves- sels by two Babcock & Wilcox marine watertube boilers operated with a working steam pressure, at the super- heater outlet, of 310 pounds per square inch and with 200 degrees Fahr. super- heat. The heating surface of each boiler is 2463 square feet, giving a total of 4926 square feet for the two boilers. Hach boiler also has a super- heating surface of 222 square feet. NGIN# room of the Onondaga. De Laval double re- duction geared steam turbine developing 1500 Sehicie es 32Gb lao) iePaVe of the propeller with steam at 300 pounds per square inch and 200 degrees Fahr. super- heat. The Ta- homa’s ma- chinery is iden- ticai Onondaga, completed by the Defoe Boat and Motor Works, Sept. 11, 1934 MARINE REviEw—October, 1934 Cinta rrr ho The boiler tubes are of 2-inch diame- ter. Hach boiler is fitted with three Babcock & Wilcox, Cuyama type, oil burners. Feed water regulators and desuperheaters were also supplied by Babcock & Wilcox Co. Diamond Pow- er Specialty Co. soot blowers are in- stalled. There are two turbine driven elec- tric generators, each of 35 kilowatts capacity for supplying electricity for all auxiliary purposes. These genera- tors were supplied by the De Laval Steam Turbine Co. The feed pumps, two for each vessel, supplied by Warren Steam Pump Co., are vertical simplex double-acting, each having a capacity of 26,000 pounds per hour. All the other pumps were sup- plied by the De Laval Steam Turbine Co., and include one turbine driven propeller type main circulating; one centrifugal, electric motor driven, aux- iliary circulating; two centrifugal electric motor driven, main conden- sate; one centrifugal, electric motor driven, auxiliary condensate; one cen- trifugal, turbine driven, fire pump; turbine and motor driven fuel oil pumps; two lubricating oil pumps; one centrifugal, electric motor driven, bilge pump; and one centrifugal, electric motor driven, sanitary pump; two 80- gallons per minute against 35 pounds pressure oil circulating pumps. The electric motor driven pumps are fitted generally with Star electric motors, connected by flexible couplings. 23