278 DESIGN AND CONSTRUCTION OF PASSENGER STEAMERS. 



In addition to resistance and estimated horse-power curves, the experimental work now 

 being done on model propellers, both in free water and behind ship models, calls for 

 commendation. This is a field that has been opened up comparatively recently. 



In addition to deep-water conditions, attention is given to shoal-water problems, so 

 important in connection with inland navigation. Destroyers at high speed some time ago 

 proved that the two forrns of navigation were different. I well remember the case of one 

 of the last of our coal-burning destroyers ; a chart showing the results of some Denny shoal- 

 water experiments was on board, but the practical people looked at it askance until they 

 tried to get 24 knots, in water entirely too shallow, for the same power as in deep water. They 

 knew something was wrong, and finally it began to dawn on them that there might, after 

 all, be something to that blandly ignored chart, so they decided to haul off into deeper water, 

 with the result that all promptly went well. 



It is also known that lines suitable for deep water are not necessarily good for shoal 

 water. 



Coming to passenger liner speeds, before the war we had reached 26 knots for all the 

 way across the Atlantic, this in the Lusitania and Mauretania. In the later Cimarder Aqui- 

 tania we see a reduction to 23 knots, while the large White Star boats ran in the neighbor- 

 hood of 21. About the maximum for the long routes to the Cape, India, and Australia was 

 18 knots. 



Referring to the paragraph headed "Trend of Design," it is evident that moderate speed 

 will be a feature of new construction for a while. Referring to the paragraph headed 

 "Length," the average speed for the fourteen postwar designs for all trades there discussed 

 is about 16>^ knots with a range of from 14 to 18 knots; it must be noted that in three or 

 four cases the speed was not obtainable. It is, however, obvious that speed in representative 

 liners has been cut down from that which obtained before the war. It is seen that the evi- 

 dence is all for moderate speed, even on the North Atlantic, which is another way of saying 

 that this particular route is contenting itself at present, at least as far as new ships are con- 

 cerned, with vessels that average up well with those on the general routes of world travel, 

 instead of the accustomed 21 to 23 knots of the old days. In the attainment of better results, 

 the competition in systems of propulsion does, and will to a greater extent, contribute to a 

 lower consumption of fuel per horsepower. The problem is three-fold — lower resistance, 

 better wheels, and more economical power plants. The question of inexperienced engine- 

 room forces has troubled us lately but should become less prominent as conditions improve ; 

 men gain experience and faults of design and construction are eliminated. 



The new C. P. O. S. liner. Empress of Canada, completed this year, has a speed that is 

 decidedly in advance of the present trend. She will be the largest vessel on the Pacific, ac- 

 cording to current reports, being about 1 20 feet longer than the American Legion type. She 

 is annoiuiced to have made well over 20 knots on the mile and to be designed for 18 knots 

 in service. One report credits her with 25 knots on the mile; if so, the owners are to be 

 congratulated on having a vessel which lacks nothing of Atlantic liner standards except 

 extreme size. Her entry into the service will be felt among competing lines, who will have 

 to look to their laurels ; the turn of speed she is capable of will be very useful when it be- 

 comes again economically practicable to burn the fuel. 



Speed has an effect on design that is not clear at first glance. The piling up of deck 

 houses is a noteworthy feature of many modern vessels. In the next paragraph we discuss 

 very high speed liners of warship type as far as dimensions and proportions go. High 



