NOTES ON FUEL ECONOMY. 231 



The data below can be vouched for, the two vessels being tried over the 

 same course, Delaware Breakwater; both were deep load draught trials and 

 progressive runs were made. 



It will be noticed that the displacement of the larger vessel, the model 

 of which was tried in the tank, is 46 per cent in excess of the smaller, and the 

 power identical at cargo vessel speeds. The larger vessel would take even 

 less power at sea than the smaller on account of size. The first vessel is an 

 oil tanker and the second a U. S. naval collier of the Mars class. 



The figures below speak for themselves: — 



Year of Completion 



Item. 1903. iQog. 



Length 360 ft. o in. 385 ft. o in. 



Breadth 46 ft. 3 in. 53 ft. o in. 



Draught 20 ft. 7 in. 24 ft. 8 in. 



Displacement in tons 7,700 1 1,260 



Block coefficient . 786 . 784 



Propulsion, system of Single screw Twin screw 



I. H. P. for 10 knots 1,525 i,550 



I. H. P. for II knots 2,125 2,100 



I. H. P. for \\\ knots 2,500 2,400 



I. H. P. for 12 knots 2,800 



Deadweight carried in tons 5,000 7,400 



ExampIve; no. 2. 



An interesting case of extravagant design came up recently. A ship- 

 ping firm had plans of an eleven-knot steamer built in Europe of the following 

 general dimensions: — 400' 0^X52' o"X 34' o". They wanted a duplicate 

 built here, but with machinery for ten knots only. The suggestion that the 

 steel hull could be built 6 per cent cheaper to modified dimensions without 

 affecting the coal bill was rather a shock to the prospective owners. The 

 vessel as redesigned, with identical deadweight, draught and cargo capacity, 

 worked out at 370' o" X 54' 6" X 35' o" . The power worked out as follows : — 



Item. 400-ft. ship. 37o-ft. ship. 



Skin B. H. P 685 645 



Residuary E- H. P 365 405 



Total 1,050 1,050 



