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January, 1916 tricity; the pilot house is completely equipped with all modern appliances, mechanical telegraph, house _ tele- phones, spider telephone system, and a navigation. telephone system. Two 5-inch centrifugal pumps, electrically operated, can quickly drain the barge and the ballast tanks. The barge is further equipped with two refrigerating plants, one for the crew, and one for the cargo capable of maintaining a temperature of 35 degrees for a cargo of 6,000 cubic feet. The cargo space is covered by a waterproof steel cargo box, which is straddled by an electric traveling gantry crane capable of extending a boom outward on either side for a distance of 70 feet and then lift one ton. Finally, the barge is equipped with a 15-mile launch, a skiff and life raft. “The Variation in Frictional Re- sistance of Ships With Condition of Wetted Surface’ was the title of a paper read by William McEntee, naval constructor, U. S. N., navy yard, Washington, D. C. A paper dealing with the resistance of ships from a different standpoint was presented by E. H.° Rigg, naval arthitect, New York Ship Building Co., Camden, N. J. Portions of Naval Construc- tor McEntee’s paper follow: “In considering this general sub- ject two queries naturally arise. On actual ships what is the increase in resistance due to fouling? Is it pos- sible to reduce the frictional resist- ance by modifications in the condition of the frictional surface, or by the application of materials that would tend to make the surface smoother? “The method adopted to investi- gate this subject was to expose to fouling in sea water 12 10-pound steel plates 2 feet wide by 10 feet long, painted with two coats of anti-cor- rosive paint. The plates were placed in the water July 10, 1914, at a point in the Chesapeake bay near:the navy yard, Norfolk, Va. where the water ordinarily has a density of 1.02; that is, contains about 75 per cent as much salt as is ordinarily found in sea water. The plates were removed from the water at intervals of one month, care- fully packed so as not to remove any of the fouling, which consisted mostly of small barnacles, and shipped to the model basin, where they -were tested to obtain the frictional resist- ance. “Fach plate as received at the model basin was tested at speeds rang- ing from 1% knots to 8 or 9 knots. The plate was then carefully cleaned, scraped and repainted with a coat of Norfolk anti-fouling paint and re- tested at the same range of speeds as when fouled, and the coefficient and exponent for the clean condition determined. The fouling matter re- moved from plates was weighed so as to give a measure of the amount of fouling. ° The results indicate the im- portance of keeping a vessel’s bottom clean and well painted, though it 1s not considered that the relative effect on a-ship’s resistance due to an equal amount of fouling would actually be as great as that obtained in these experiments, as it seems probable that the decrease in frictional coefficient due to increase of length would be relatively greater for the foul condi- tion than is found to be the case for clean, smooth surfaces. “At various times attempts have been made to reduce the frictional resistance of ships by lubricating the under-water surface or by polishing it to a high degree of polish with various materials. One favored meth- od used for racing yachts is to polish the bottom with black lead or graph- ite. An investigation of the benefits to be expected from such polishing or lubrication has recently been made at the model basin with friction planes. The two planes used were those with The New Officers” President. STEVENSON ‘TAYLOR, Quintard Iron Works, street, New York. Vice Presidents. H. I. Cone, Commander, Navy Depart- ment, Washington, D. C. Lewis Nixon, 22 East Fifty-third street, New York. G. W. Dicxisz, naval architect and marine engineer, 24 California street, San Francisco, Cal. G. E. WEED, New York. Members of Council. H. A. Macoun, vice president, York Shipbuilding Co., Camden, N Naval Constructor W. J. Baxter, U.S.N., Navy Yard, Boston, Mass. ANDREW FLETCHER, president and treas- ae North River Iron Works, Hoboken, vice president, 742 East Twelfth 32 West Fortieth street, New ye R. H. Roptnson, general manager, Lake Torpedo Boat Co., Bridgeport, Ct. W. D. Fores, consulting engineer, 236 Hempstead street, New London, Ct. Coxe, president, Harlan & Holl- ingsworth Corporation, Wilmington, Del. Associate Members of Council. J. S. Hype, president and_ general manager, Bath Iron Works, Bath, Me. Harvey D. Goutper, proctor in ad- miralty, 915 Rockefeller building, Cleve- land, O. Executive Committee. Chief Constructor . Capps, U.S.N., senior member, Board of Hull Changes, Atlantic Coast, Room 412, Post Office building, Philadelphia, Pa. Lewis Nixon, 22 East Fifty-third street, New York. W. I. Bascocx, engineer and naval architect, 17 State street, New York. ANDREW FLETCHER, president and treas- car North River Iron Works, Hoboken, ey, W. M. McFarranp, Babcock & Wilcox Co., Singer building, New York. Secretary-Treasurer. D. H. Cox, naval architect, 15 William street, New York. which the frictional coefficients of several ship bottom paints were de- termined a few years ago. These planes are roughly 20 feet by 2 feet by 34-inch, with ends sloped forward at an angle of about 30 degrees. Total wetted surface for each is about 82 square feet. The planes were sand- papered smooth and coated with shel- lac, and in this condition were each towed in the water at speeds ranging from. 1 to. 11. knots. “One plane was next coated with black lead or graphite, which was mixed in sour milk and applied with a brush to the shellacked surface of the plane. When dry, the lead was rubbed down to a fine, smooth polish. Ten runs were made with this plane at speeds from 5.1 to 6.5 knots. The graphite seemed to cling well to the surface and showed no abrasion or wear. When wet, however, it was easily rubbed off. The next material THE MARINE REVIEW a tried was ordinary ivory soap, which was mixed as a thick emulsion in water and applied with a brush. The plane was run at speeds from 6 to 9 knots. The soap left a whitish streak in the water the first run, but not thereafter. The resistances obtained on all of the runs were consistent, so that the quality of the .surface was probably unchanged during the course of the experiments. “Two other lubricating materials experimented with were heavy cylinder oil and light cylinder oil. The oil was applied to the shellacked surface of the plane when dry with a brush, the plane being suspended over the posi- tion in which it was attached to the towing carriage, so that it could be tun in the water as quickly as possible after the application of the oil. The plane with the heavy engine oil was run at speeds from 6 to 8% knots. The observations obtained were con- sistent, but the slope of the resistance line when plotted on log paper indi- cated that at speeds of about 3 knots the frictional resistance would fall below that of the smooth, shellacked surface. This peculiarity is possibly due to the fact that parts of the oil formed in drops or globules and wave- lets, increasing as the speed increased, thus changing the condition of the surface which might, if tested at lower speeds, not have given results lower than shellac. The experiments with the light engine oil indicated that for the first two runs the resistance was a small percentage greater than for the shellacked surface. Apparently as the oil was washed off the resistance de- creased until the resistance agreed with that previously obtained with shellac. “The results of the experiments in- dicate that no advantage over a smooth varnish or shellacked surface is ob- tainable with the materials used. For each lubricating surface the resistance is greater than for the shellacked surface. The resistance increases in the following order: Black lead, light oN iba oil, ivory soap, heavy cylinder oil. Portions of Mr. Rigg’s paper, which bore the title, “The Determination of the Resistance of Ships,” follow: “Of late years an increasing number of merchant vessels have been built with the form of stern considered pe- culiar to battleships and _ cruisers. There is much to be said in their favor and the effect on speed. may well be noted here; for a given overall length this stern gives the maximum mean immersed length and a result- ing decrease in power and _ conse- quently machinery weight, necessary for a given speed, varying with the size of the ship. being greater in the smaller ship. The adoption of this stern is attended with increase in sta- bility, in deck room and in protection to screws in harbor. The chief ob- jection is increased first cost. Ap- nearance is another in some eyes. But small increased first cost will have a hard struggle against a possi- ble 8 per cent saving in coal bills. The arguments are very much in favor of the cruiser stern for all twin or more screw designs, with a good chance in the single-screw design pro- viding the draught is large. Modified cruiser sterns are common in our waters for ships that do a large