PROGEESS IN MARINE CONSTRUCTION GRACIE. 697 



and Ulster^ which, on a length of 360 feet, attained a speed of 24J 

 knots, a speed-length ratio of 1.28, and the Empress Queen, still the 

 largest paddle vessel in this country, 360 feet in length and of 21^ 

 knots speed. 



In 1903, encouraged by the success of the turbine steamers Kiiig 

 Edward and Queen Alexandra, built, respectively, in 1901 and 1902 

 for service on the Firth of Clyde, the first turbine channel steamer, 

 The Queen, was placed on the Dover-Calais route. This notable ves- 

 sel, 310 feet by 40 feet by 25 feet, of 1,676 gross tons, has turbine 

 machinery of about 8,500 horsepower, and attained a speed of 21.8 

 knots, equal to 1.24 times the square root of her length. In the same 

 year the turbine steamer Brighton, 274 feet in length, steamed 21.37 

 knots, giving a speed-length ratio of 1.29. The success of these two 

 vessels led to a rapid development of turbine propulsion, and the 

 almost total abandonment of reciprocating machinery in the channel 

 services. In 1905 the Princess Elizabeth, with turbines and water- 

 tube boilers, made 24 knots on 357 feet, and the Diepjje, with turbines 

 and cylindrical boilers and classed at Lloyd's, brought the speed- 

 length ratio up to 1.31, with 21.65 knots and a length of 274 feet. 



To attain high speeds in relation to length, saving of weight is of 

 vital importance, and the advantages of water-tube boilers in this 

 respect are considerable. All that prevented their more general 

 adoption was their lack of robustness and the greater care and skill 

 required in handling them, as compared with the well-tried and 

 well-known Scotch type of steam raiser. By their use in the tur- 

 bine steamer Newhaven, built in 1910 as successor to the Dieppe, a 

 trial speed of 23.85 knots was obtained on a length of 292 feet, the 

 speed-length ratio being raised to 1.4. This result was made possi- 

 ble by the extreme lightness of the machinery installation in relation 

 to the power developed, 13,000 horsepower being obtained from a 

 weight of only 590 tons. Thus 22 shaft horsepower was developed 

 per ton, about two and a half times that obtained from paddle ma- 

 chinery and double the output of twin-screw reciprocating engines. 

 The displacement of the Newhaven was 1,510 tons, only 200 tons in 

 excess of that of the Dieppe, although the later vessel was 18 feet 

 longer and twice as powerful. 



The outstanding difficulty in applying the steam turbine to marine 

 propulsion has always been that while high speed of rotation is neces- 

 sary to obtain the maximum turbine efficiency, the propellers are most 

 efficient at very much lower speeds. Electric, hydraulic, and gear- 

 Avheel transmission have each been used to combine a high-speed 

 turbine with a slow-running propeller in order to obtain the maxi- 

 mum efficiency of each. 



Where a suitable gear ratio can be adopted, not only can improved 

 propeller efficiency and decreased consumption of steam per unit of 



