372 F. H. Todd 
and without parallel body, and rectangular hulls having rounded corners. The deadweight/ 
displacement ratios depend upon the size of the ship and its speed, and some representative 
figures taken from the reference are given in Table D1, as they are of general interest. 
Table D1 
Deadweight/Displacement Ratios (from Russo, Turner, and Wood) 
Speed 2 Parallel | Length | Beam | Depth 
. Deadweight = 20,000 tons 
20 Circle 0 525 75.5 | 75.5 
Power Increase 
for Rect. 
Section (%) 
20 Rect. 59.5 555 80 40 62 
30 Circle 0 560 79.0| 79.0 - 
30 Rect. 58 570 90 40 40 
ao = 30,000 tons 
20 Circle 85.5] 85.5 
20 Rect. . 8 oe 100 40 
30 Circle 625 89.5} 89.5 
30 Rect. a 5 625 120 40 : 
Deadweight = 40,000 tons 
660 93.5 | 93.5 
. 6 710 120 40 : 48,400 
oe 98.0} 98.0 : 104,400 
120 : 152,000 
Circle 
Rect. 
Circle 
Rect. 
For the tankers having circular sections the ratio at 20 knots varies from 0.546 at 
20,000 tons deadweight to 0.566 for 40,000 tons. At 30 knots the corresponding figures are 
0.467 and 0.500. These ratios are referred to surface displacement. If we convert them to 
submerged displacement, which is the one used in my paper, the values become 0.496, 
0.515, 0.425, and 0.455 respectively. These values are all appreciably less than the 
figure of 0.60 used in the original power estimates. The latter have therefore been 
revised, using the new deadweight/displacement figures as derived above, but otherwise 
they are upon exactly the same basis as the earlier estimates. The calculated powers are 
shown in Table D2 and the appropriate spots have been added to Figs. 9, 10, and 11. For 
the smallest tanker, of 18,750 tons deadweight, the circular-hulled submarine now requires 
exactly the same power as the surface tanker at 20 knots, so that the crossover point (for 
smooth water operation) has been raised from about 11 knots to 20 knots. The same 
applies to the intermediate 56,250-ton-deadweight tanker, the crossover rising from 14 knots 
to 20 knots. For the largest ship, of 93,750-ton deadweight, the submarine tanker does not 
become less resistful than the surface ship (in smooth water) until the speed is some 
28 knots. 
These figures substantially agree with those suggested by Mr. Newton. | was aware at 
the time of writing the paper that the assumed value of 0.6 for the deadweight/displacement 
ratio was probably high, especially as many of the examples originated from the protagonists 
