Maritime History of the Great Lakes

Marine Review (Cleveland, OH), December 1913, p. 427

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December, 1913 The experimental tank at Washing- ton, D. C.,: has been of great assist- ance to shipbuilders in determining the exact power required to drive any particular model a certain speed on a certain horsepower. These models are usually made of wood carefully sand papered and varnished, an exact reproduction of the proposed vessel, and drawn through the water at dif- ferent speeds, carefully noting the power required at each step. While we know that the resistance of a ship moving uniformly at any speed may vary as the square of that speed, the power to overcome that resistance and propel it at any speed varies as the cube of that speed. But so many elements enter into the calculations tor speed, such as resistance due to skin friction, resistance due eddy mak- ing, resistance due to wave making, that it requires very experienced hands to calculate with nicety the required power without the use of the fank asa -¢heck on their calculations. The yacht is in an entirely differ- ent class 3srom either of the other types mentioned. It usually has very fine lines, and is designed for speed and for the comfort of the rich own- er. She must be a thing of beauty and grace, cabins and interior finished in-the rarest woods as expense is usually no object. The American shipbuilder finds so little profit in this line of work that he is well sat- isfied to allow his English brother to monopolize the business. One of the finest specimens of the naval archi- tect's art is the new Winchester, with a speed of 32 knots, built by Yarrow & Co. for Peter Rouss, of New York. The aim of the engineer. is to obtain the design of least weight consistent with the greatest strength. In other words, to give the greatest possible carrying capacity. It is with this end in view that the so-called Isherwood system of vessel construc- tion has been introduced. The Isherwood System By the Isherwood system we mean the main framing of the vessel is longitudinal, or runs fore and ait, 'instead of transversely, thus insuring a lighter boat and a stronger con- struction longitudinally, besides hav- ing advantages from a shipbuilding standpoint, In the old method of Construction, liners are necessary be- tween the framing of the vessel and the plates, due to the lapping of same. These liners amount to about 2 per ent of the shell. A vessel construct- ed under the Isherwood system will feigh from 8 to 10 per cent lighter or the same strength than the trans- erse method, and enable her to carry 'stresses than a land engine. THE MARINE REVIEW more cargo on the same draft. The successful engineer must de- sign the engine so that metal is placed where it is most needed and of the best section to give greatest strength and lightness. As a rule, the' marine engine is designed to stand greater Often it means loss of the vessel to have a break-down occur at sea. The United States government spec- ifies a certain number of horsepower for each ton.of machinery, in order to keep the. installation as light as possible. This calls for the skill and ingenuity of.the. marine designer who, whether it is demanded or not, should use his material to the best advantage. To put more metal into a machine than is needed is poor designing. Of course, there is danger of going to the other extreme, and the factor of safety must be liberal. Value of Observation "Then there is always the business side to be considered. Though an undertaking may be a complete en- gineering success, if the financial part is not. satisfactory there is small credit. for the engineering end. It may have failed through lack of proper supervision in the shop or on the: field, of it may have been, the designs were expensive from a ma- chine shop point of view. A little more consideration in the drafting room might have saved the profit. I have spoken of the great value of observation. Among the most prized possessions of engineers are their private note books. Text books and treatises are great helps to them, but the personal notes and sketches of good details, the results of personal experiences jotted down from time to time, also well tried formulas and re- sults of tests that they have from their own knowledge secured and know can be depended upon, are of the greatest value. The modern warship, ocean liner or first-class cargo steamer is becom- ing more and more a concentrated power station or great machine shop. The old-fashioned sailor is fast dis- appearing, sails and rigging are be- coming a thing of the past. The comforts and luxuries of every sort demanded by the traveling public have made the ship more of an engineering problem than formerly. The marine engineer must have a good idea of electrical engineering, as this equipment is becoming more and more of a necessity on shipboard, and is likely soon to be used on all auxiliary machinery. apparatus on warships and big liners is enormous--the cost of electrical The electrical . 427 equipment on one of our latest battle- ships was $300,000. Ship ventilation is being widely used. The Seeandbee has. the Mc- Creery system and washes the air before forcing it through the saloons and all other parts of the ship. Ven- tilation has become a specialty in it- self in marine engineering. Refrigeration has become another important feature in the equipment of vessels. All passenger steamers and the better class of freighters have their own refrigerating plants. Re- frigeration has revolutionized the method of carrying perishable foods such as beef and fruit. Steamers especially designed for this trade are marvels of engineering skill. Sanitary and hydraulic engineering . figure largely in the design of a mod- ern passenger steamer. The decorations and interior' finish of an up-to-date liner afford a won- derful scope for the artistic ability of the naval architect. The Diesel oil engine, or the in- ternal combustion motor, has opened up a new and interesting field for the marine engineer. While. so far not very much has been accomplished in this country, a great industry has been developed abroad, and a large fleet of Diesel-propelled vessels are in the commerce of the world. Tank- ers up to 15,000 tons displacement are being built with this type of motor, as well as some German war- ships. At present there are but two of any size being operated on the great lakes. The Calgary, of about 700 h. p., and the Fordonian. of 900 h. p. Both of these .are foreign-built vessels and Canadian bottoms. The Diesel Motor The chief difficulty for the Diesel motor in the United States, where coal for marine purposes is so cheap, is the uncertain supply of crude oil or petroleum, which cannot at pres- ent be satisfactorily or regularly pro- cured at a reasonable price. If this were not so, I can see no reason why this method of propulsion would not rapidly supercede the present steam engine, the principal advantage being economy in operation as regards the amount of fuel consumed which is only about four-tenths of a pound per horsepower, while the coal con- sumption is from 1% to 2 Ibs: 7A smaller engineering force, the weight and space gained by doing away with the boilers and coal bunkers, con- venience of fueling, as it requires no trimming, the radius of steaming un- der one fueling, the saving of fuel while the vessel is in port and many

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