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www.sname.org/sname/mt April 2013 highest speed vessels at 35.2 knots before 1900. ese 194- ft. torpedo boats, with IHP = 12,000, were reported by the United States O ce of Naval Intelligence to be ?the fast- est ships in the world.? Significant developments occurred in the 1890s. Sydney W. Barnaby joined John I. ornycroft & Co., Ltd. and participated in propeller experiments at their private test facility. In 1885, he published the rst of six editions of a book entitled Marine Propellers , which included such topics as screw propellers, paddle wheels, and hydraulic propellers (waterjets). Later, H.M.S. Daring , a torpedo-boat destroyer designed and constructed by ornycroft for a British Admiralty, was short of meeting the contract speed of 27 knots. Following a series of sea trials in 1893 with six di erent propeller designs, required speed was attained, but most importantly, Barnaby analyzed the data to develop and publish, in 1894, the rst propeller sizing criteria to avoid or minimize the e ects of cavitation. is initial cavitation criteria indicated that maximum propel- ler loading must not exceed 11.25 pounds of thrust per square inch of projected blade area. Englishman Charles A. Parsons developed the steam turbine, which was demonstrated in the launch Turbinia , built to his design. Parsons initial steam turbine instal- lation in 1894 under-performed, only 19.7 knots; with instrumentation, also of his design, he made torque mea- surement on the shaft that determined that the propeller could not absorb available turbine power. Using propeller cavitation criteria from Barnaby, Parsons then developed the rst test facility to visually observe the propeller cavi- tation problem. In 1897, Parsons recon gured Turbinia with a three-stage turbine, one stage per shaft, with each shaft having three propellers to obtain su cient blade area to meet Barnabys criteria, for a total of nine propel- lers. Turbinia ultimately attained 34.5 knots. The concentration of vessels exceeding twice hull speed after 1890 suggests that significant technology advances occurred during that period. De ning these advances necessitates that some speculation be used to ll in voids not reported in written documents or draw- ings. Little is known about speci c hull geometry of the exceptional boats, except that LOA/BOA was between 7.5 and 10.4 with an 8.6 average and slenderness ratios were about 9.3 (varying between 8.3 and 10.3); few graphics giving transverse sections were available. Some centerline pro les and general arrangements provide some sense of bow and stern waterline endings. All of the vessels were propelled by screw propellers. Developments in hull lines are more speculative, how- ever; all were round bilge forms. Early hulls were double ended, becoming beamier at the stern to reduce squatting as speed increased. Higher-speed boats had ne forebody and vee sections (without chines), to cut easily through the water. It has been implied in text descriptions that Normand (a Frenchman) and Mosher (and American) employed hook or wedge? in the aft buttocks to increase lift. is would be a logical approach for buttock shape when one looks back from todays technology. Between 1890 and 1904, seven vessels reported greater than twice hull speed, F nL > 0.80. Five were designed by Charles D. Mosher, one by Charles A. Parsons, and one by Nathanael G. Herresho . Little is known about the Figure 2: Build dates of signi? cant vessels and record dimensionless speeds