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Some Surprising Figures Comparison of Earnings of a Steam Ship and a Krupp-Diesel Motor-Driven Ship LTHOUGH the benefits to be A enjoyed by substituting Diesel engines for the best types of modern steam engines are very real in comparatively small vessels, those same benefits become more and more. pronounced: as the size" of the ship increases. To make this plain to those interested, the following complete plans of two ships of the largest size, exactly alike as to di- mensions, displacement, speed and en- gine power and differing only in the respect that one is a steamship, while the other is a Diesel-engine-driven motor ship, have been prepared and are shown herewith. To begin, the general particulars of these two ships are as follows:«< Length, /22 ft. 5 in:; breadth, 78 ft.; draught, when loaded, 33 ft.; displacement, 36,000 tons; shaft horsepower, 20,000; twin screws; sea speed, 19 knots. The foregoing particulars are com- mon to both ships, but here the sim- ilarity ceases. In the case of the steam- ship the engine and boiler compart- ments taken together extend for a length: of 315 ft. and occupy 702,768 cu. ft., while in the case of the Diesel- engine-driven motor ship the engine compartment is but 167 ft. long and occupies but 430,843 cu. ft. The dif- ference between the size of these two machinery compartments is 271,925 cu. ft., and because each 35 cu. ft. of this space is considered to be a ton for freight earning purposes, it is very evident that if we divide the difference between these two machinery spaces by 35, we get the amount of extra freight room that the motor ship can utilize for increased freight earnings. This comes to 271,925 cu. ft. + 35 equals 7,700 tons. The steamship, however, must carry its coal in bunk- - ers and these bunkers must have a capacity of 44 to 45 cu. ft. for each long ton of coal carried. This coal bunker space must all be above the boiler room floor plates and hence is space that might otherwise be used to stow cargo. The oil ship carries her oil in tanks, which are a part of her double bottom, so she uses up no part of her cargo space to stow her fuel. So the capacity of this steamship's bunkers, designed to hold sufficient coal for 18 days of 24 hours each, continuous steaming at 19 knots must be at least 255,200 cu. ft. and this last *Engineer American Krupp-System Diesel Engine Co. figure divided by 35 gives 7,300 tons of valuable cargo space that in the coal-fired steamer is given up to its fuel. This latter amount must be added to the 7,700 previously obtained and we get 15,000 tons as the amount of additional freight room in measure- ment tons, which the Diesel-engine- driven motor ship can make use of in earning extra freight money. If the voyage were from New York to Ham- burg and back again, the freight might total $11 per ton for the round voy- age. That means the handsome sum of $165,000 earned by the motor ship over and above what could possibly be earned by her rival, the steamship. If these two vessels are on a route where there is plenty of measure- ment freight all the year round, then by the end of the year the Diesel- engined motor ship has earned in freight money $1,980,000 more than her rival, assuming 12 round trips possible per year. Expense of Crews We come now to expense of the crews that are needed to man these two vessels. Because they are sup- posed to be alike in every' other respect, we need not consider any of their crew except those required to tend their machinery. The steamship carries 180 men in the engine room, boiler room and bunkers; the motor ship carries but forty men in her en- gine room, so that the wages and food of 140 persons is saved every month. This might easily amount to $7,000 a month calculated as $35 a month wages and $15 a month food for each man. For twelve months this comes to $84,000 and mu&t be added to the $1,980,000 of increased annual freight earnings previously calculated. The difference in the cost of fuel used is not so easily determined because within a year a motor ship left New York harbor with her double bottom full with 1,000 tons of high grade fuel oil that cost her owners but 234 cents per gal, or $8.25 a ton, and another motor ship sailed from Norfolk for Europe with oil that cost her 5 cents per gal. or $15 per ton. Lest this great variation in price should be con- sidered peculiar to oil, it is well to bear in mind that there are many ports in different parts of the world where coal, and that, too, of an in- ferior quality, is only to be purchased By John L. Bogert* for $10 a ton and upward, while good coal in the bunkers of a ship may cost as little as $3.50 a ton and does not usually exceed in price $4 a ton bunkered in any port on the Atlantic coast. The motor ships of the East Asiatic Co., of, Copenhagen, which trade between Europe and the far east, use a distillate obtained in Bor- neo that costs them $7.50 per ton and carry enough of this cheap oil in their double bottoms to make it un- necessary to purchase fuel oil in any port in Europe. Tar-oil, a by-product of coke ovens and gas works, is pur- chaseable in Europe and also in this country for about 334 cents a gal., or, because its specific gravity is about equal to that of water, for about $10 per ton. It is likely that in the years that are to come this same tar oil will prevent an unjustifiable rise in the price of petroleum distillate. It is not at all unlikely that good fuel oil, meaning an oil of 18,000 B. T. U. free from sulphur, will before long grad- ually settle to a price of say $10 per ton in the port of New York, while equally good coal sells at $4 per ton. Taking these figures as a. basis of- comparison the steamship will burn 4,950 tons of this coal at $4 per ton, or $19,800 worth of coal per round trip New York to Hamburg and the Diesel-engined motor ship will con- sume 1,320 tons of fuel oil at $10 per ton, or $13,200 worth of oil per same round trip. The difference, $6,600 in favor of the motor ship, will amount to $79,200 per year, assuming 12 trips per year. Hence on a route of 3,500 knots where measurement freight rates are in force based on 35 cu. ft. to the ton, and where those rates average $11 per ton for the round trip the possible saving of such a Diesel-en- gined motor ship as we are illustrating over a strictly first-class steamship of the same size might be expressed in increased freight earnings and de- creased operating expenses as $2,143,- 200. Lest these figures of possible in- creased earnings should appear too startlingly large to seem creditable, it may be well to point out that a ton of measurement as employed by the German trans-Atlantic liners is 1 cu. meter, which is equal to 35.315 cu. ft. Neglecting the decimal, this is very exactly the volume of one ton of sea water, so that 15,000 tons by measurement of increased cargo car- rying space is also 15,000 tons out of