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to be the most economical ship in the world. Unfortunately foreign operators of diesel ships do not freely divulge ac- tual operating costs, which in this de- pression are vital in successfully com- peting at greatly reduced rates for pas- senger and freight business. However, at the recent trials of a sister ship, the Europa, fuel consumption was estab- lished at 0.36 pound per brake horse- power per hour for all purposes. It was claimed that the mechanical effi- ciency of the power plant would be increased by 4 per cent after the en- gines had been run in, in service. Recovery of Waste Heat The hotel load, usually a direct addi- tion to the fuel consumption of the steam propelling plant, is provided in modern motorships by the utilization of the waste heat recovery from the exhaust gases and jacket cooling wa- ter. The north Atlantic diesel pas- senger ship BRITANNIC has five waste heat boilers producing 10,000 pounds of steam per hour for general ships purposes. The comparatively large de- mand on ship board for hot water in kitchens, baths and passenger cabins offers far more favorable utilization of diesel waste heat than the average land power plant. The production on the BrRITANNIC of % pound of steam per brake horse- power from exhaust gases, increases the thermal efficiency of the diesel superheated-steam land power plants, with very large units, have attained thermal efficiencies of around 27 per cent; but 25 per cent for the smaller installations used in ships may be taken as a high figure which indicates clearly that the most modern steam passenger vessels require from 50 to 100 per cent more weight of fuel than the most modern diesel ships. The statement is often made that because a ship is seldom fully loaded, the extra carrying capacity of the diesel ship is not a valuable advantage. But, in all fairness, the diesel ship should accordingly be built smaller than the steamer for the same expected pay cargo; and it usually is, with di- rect saving in first cost. Or the addi- tional bunker capacity may be utilized by the diesel ship operating on any trade route to purchase enough fuel for the round voyage at the particular port of call where fuel is cheapest; or, again, to purchase excess of such cheap fuel above its own reqirements for sup- plying other ships of its owner or for sale at its home port. It is obvious that a diesel ship op- - erating from New York to the West coast of South America will bunker at Panama, where diesel fuel costs less than at New York or New Orleans. In general, American and foreign ships compete on the same trade routes and would fuel at the same, most favorable, world ports. Consuming fuel at approximately Fig. 3. Diesel, 4000 S. H. P. with World’s Largest Solid Injection Cylinders plant to around 43 per cent. Further heat utilization of available hot water, may easily result in passenger ships, in increasing this thermal efficiency to above 50 per cent, whereas full utiliza- tion of all recoverable waste heat from engine cooling water and exhaust gases, would increase the thermal effi- ciency of the diesel power plant to over 75 per cent,. In fact, land plants utiliz- ing diesel waste heat for evaporation of sea water have established diesel overall thermal efficiencies of above 80 per cent. The most modern of high pressure, 46 one-half the rate, the diesel ship will run approximately twice as far as the steamship on the same quantity, sav- ing time and expense in bunkering and buying fuel where cheapest. As a naval auxiliary, the diesel ship is capable of long voyage operations independent of foreign naval bases. In the great war we were fortunate in being able to use the ports of an ally across the Atlantic as a fueling base. It is hardly safe to count on a recurrence of these cir- cumstances in future wars, even if we remain neutral. Consider that the splendid fast MARINE REVIEW—November, 1931 Japanese motorships recently appear- ing on the Pacific can travel nearly twice as far as our new American steamers without refueling; that they can quickly be converted into airplane carriers; that we lack adequate naval bases in the Pacific; and then measure the value of the double cruising radius of the naval auxiliary merchant diesel ship in time of war, or the strategic value of Germany’s 50,000 diesel horse- powered “pocket” battleship Drutscn- LAND. Cruising Speed Economy The diesel ship in war service has a further advantage over the steamship in being able to operate at low speeds with practically full load and speed economy; whereas the economy of the steamship at light loads and speeds falls rapidly. It would appear that foreign nations, with greater experi- ence in carrying on naval warfare in foreign waters, have recognized more quickly the advantage of the longer sailing radius of both the diesel man- of-war and the diesel merchant marine auxiliary. ; The smaller engine room crew of the diesel ship makes a direct saving in quarters, payroll, subsistence and lia- bility. The reduction of diesel operating cost in port are many. First there is the enormous saving in fuel in han- dling cargo. Fuel losses in banking of fires under boilers are eliminated. Like- wise, loss of time and fuel required for getting up steam is absent in the diesel ship. In changing from one berth to another full propulsive power is available within a few minutes time, often saving towing charges. The speed of the diesel ship is more con- stant, and requires only valve adjust- ment of the fuel supply to the en- gine. Also change in speed may be made instantly, over wide ranges; and higher speed demands no more effort from the crew. That the upkeep of a diesel ship is less has been established by a number of reports made by foreign shipowners operating diesel and steamships. Only minor wearing parts of the diesel re- quire replacement and the life of a diesel ship is ten years greater than that of a steamer. After 20 years in Service, the diesel propelling machin- ery of the SELANDIA is found to be good for at least ten years longer. Several motorships after seventeen years in service have been fitted with new aux- iliary boilers, while the diesel engines required no major replacements. If the life of a diesel ship may be safely taken at 25 per cent longer than the Steamship, the actual fixed charges are accordingly less. The obsolescence of diesel engines now 25 years in service is nil; as their economy and servicea- bility have neither been impaired nor exceeded by other types of power plant. Much has been written of the im- provements in steam economy during