92 ECONOMICAL CARGO SHIPS. 



of 2,240 pounds, and cost of operation per annum, these figures have been reduced 

 in each case to the basis of $1,000,000 investment; and in order to make the figures 

 more easily grasped I have assumed a gross freight rate of $6.00 per deadweight 

 ton for the 3,500 nautical mile run. From this rate, however, I have deducted 

 $1.00 per ton for handling and 15 cents per ton brokerage, showing a net revenue 

 of $4.85 per deadweight ton on this run. For the 7,000-mile run I have assumed 

 the freight rate of $10.00 with a deduction of $1.00 per ton for handling and 25 

 cents per ton for brokerage, giving a net rate of $8.75. 



The profits in operation calculated on the above assumptions have in each case 

 been figured upon the assumption that the ships are operated on each leg of their 

 route with a full cargo. This assumption is only a hypothetical one. The freight 

 rate should therefore be so adjusted that it shall bear the proportion to the assumed 

 rate that a full cargo does to the average percentage of cargo carried per trip. For 

 example, if the ship operated with an 80 per cent load in one direction and a 20 

 per cent load on the return voyage, 100 per cent load is divided between the two 

 voyages, so that only 50 per cent freight movement is achieved and the freight rate 

 would therefore be doubled to realize the profits shown in the table, Plate 39. 



RESULTS 



The results of the calculations are shown in a series of diagrams on Plates 40 

 and 41 and may be readily summarized as follows : — 



(a) The Cost Per Deadweight Ton. — Fig. i, Plate 40, shows that the cost is 

 sensitive to speed, increasing rapidly in all sizes of ship with increase of speed. 

 Fig. II, Plate 41, shows that the cost is only slightly sensitive to increase in size, 

 showing tendency to fall with increase up to about 450 feet at 10 knots and a larger 

 size for faster vessels. 



■ (b) Deadzveight Moved Per Million Dollar Investment Per Annum. — Fig. 6, 

 Plate 40, shows clearly that for large freight movement slow speed is essential. At 

 10 knots a 350-foot ship will move more cargo than any larger vessel. At 11 knots 

 the 400- foot ship is the best; at 12 knots the 450- foot ship is better, and at 13 knots 

 the 500-foot ship will move as much as any smaller size. 



(c) Profits Earned Per Million Dollar Investment. — Figs, 2, 3 and 4, Plate 40, 

 show the profits earned for a 3,500-knot run as plotted upon speed of ship, and 

 Figs. 12, 13 and 14, Plate 41, are corresponding diagrams for the 7,000-knot run. 

 Figs. 7, 8 and 9, Plate 40, show results for the 3,500-knot run plotted on the size of 

 ship. 



All these diagrams show clearly that the slow-speed ship is the money-earning 

 ship, and there is a very steady decline as the speed increases, the 350-foot ship 

 earning twice as much at 10 knots as at 13 knots. 



It will be noted from Figs. 7, 8 and 9, Plate 40, that at a speed of 10 knots a 

 ship 400 feet long gives practically the very best earning proposition that can be 

 designed, and that for 1 1 knots a length of 450 feet is probably the maximum eco- 



