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THE OIL-ELECTRIC TUGS CHAGRES AND TRINIDAD BUILDING BY THE PANAMA CANAL ON THE TOP SIDE OF THE GREAT 1000-FOOT DRYDOCK AT BALBOA, C. Z. the handling qualities of these large tugs. It is probable that, regardless of the length they will be just as handy as are the smaller harbor tugs now employed on the canal. The main propelling machinery was purchased in the United States, for delivery on the Canal Zone not later than May, 1, 1927.. EKach tug is fitted with two 4-cycle mechanical injection diesel engines, of Ingersoll- Rand make each driving a direct-con- nected 330-kilowatt, direct-current 250- volt generator and on an _ extension shaft a 50-kilowatt direct-current exciter. The two main generators, operating in series, drive a double armature 750-horsepower direct-cur- rent motor. The electrical equip- ment was furnished by the General Electric Co. The motor is direct- connected to a single propeller ap- proximately 10 feet 6 inches in diam- eter, designed to turn from 115 to 140 revolutions per minute when de- veloping full power. All auxiliaries are driven from the power developed by the two exciters when the main engines are in operation. As auxiliary power each tug is equipped with a 10-kilowatt gener- ator, driven by a direct-connected 25-horsepower 4-cycle solid injection diesel engine. An air compressor of suitable size can be driven on an extension of the auxiliary generator The photograph used to illustrate this article, and certain interesting particulars, and the Panama Canal Record, from which most of the text is taken, were sent to the editor of MARINE REVIEW by C. A. McIlvaine, ex- ecutive secretary, the Panama Canal. 30 SHOPS WITH COMPLETE SHIP REPAIR EQUIPMENT ARE SHOWN BACKG ROUND shaft through a clutch. An indepen- dent compressor, motor-driven, will be installed in each boat. The motor for this compressor is to be auto- matically controlled from the air pressure in the starting air tanks of the main engines, which will insure continuously maximum pressure for the starting air. Each tug equipped with a motor- driven centrifugal fire pump the ca- pacity of which is 1000 gallons per minute at 100 pounds pressure. The tugs have been equipped so that this pump may be used as a_ salvage pump as well. Lighting circuit and power for the ice machine motor and sanitary pump motor are taken from 125-volt mains. This voltage is obtained by stepping down exciter voltage through a motor generator. Each tug is equipped with a second motor generator which will convert the 25-cycle 230-volt current Canal Zone to 125-volt direct current, for use on the tugs. This will permit the tugs, while lying at dock, to enjoy the comforts of lights, sanitary sys- tem, and refrigeration without run- ning any machinery aboard the tug. The fuel oil capacity of each tug is sufficient to give at least 21 days’ cruising radius operating at full power, The names given the tugs, CHAGRES and TRINIDAD come from the two rivers which are the prin- cipal tributaries of Gatun lake. The shipping board motorship Wil- liam Penn, operated by the Barber line for the past four years, has been MARINE REVIEW—June, 1927 IN THE allocated to the Roosevelt Steamship line for operation in the Australian and Indian trade. The Roosevelt line has six other motorships in this serv- ice, the TAMPA, UNICOI, WEST HONA- KER, WEST CUSSETA, SAWOKLA and CITY OF RAYVILLE. Fast Diesel Freighters for Kerr Line The new 16-knot motorships being built, in England for the Kerr line around-the-world service, the first of which, the SILVERGUAVA, is to come out in July, are to have refrigerator space for 1500 tons of cargo. This has been provided primarily for car- rying California products to the Orient, according to H. S. Scott, pres- ident of the General Steamship Corp., Pacific coast agent for the line. The around-the-world service will be main- tained by the SILVERGUAVA, SILVER- MAPLE, SILVERHAZEL, SILVERASH, SIL- VERBEECH and SILVERBELLE. Each has a capacity of 9500 tons dead- weight and a normal speed of 14% knots, which can be increased to 16 knots without pressure. They are driven by 6000 horsepower Doxford engines. Engine room and deck aux- ilaries are electrically driven. Casualties to vessels of 500 tons gross register and upward during the month of March, according to returns compiled by the Liverpool Under- writers’ association, were 15. total’ losses and 617 partial losses, as com- pared with 11 and 642, respectively, for the same month of 1926.