Submarine Cargo Ships and Tankers 373 
of the submarine cargo ship. Indeed, in an earlier paper* I had used a value of 0.5, but felt 
it necessary to err on the side of optimism rather than to run the risk of being charged with 
pessimism and lack of foresight! This comparison is for circular-hulled submarines, which, 
of course, suffer from the extreme drafts noted in the paper. In the American paper referred 
to, power requirements are also given for rectangular section submarines, some of which are 
shown in Table D1. While this type of section enables the draft to be kept within reason- 
able bounds (not greater than 40 feet for 40,000 tons deadweight) the price to be paid in 
power is very considerable, varying from 60 to 80 percent increase at 20 knots and 40 to 50 
percent at 30 knots. These powers are higher than those given in my paper for elliptical 
sections, but, of course, they have the advantage of less beam. With limitations on beam, 
draft, or both, forcing us to adopt elliptical or rectangular sections, it is obvious that the 
commercial merits of the submarine tanker as compared with those of her surface sister will 
be hard to find, even when allowance is made for rough sea effects upon the surface ship, 
as long as there is no demand for the high speed (and therefore high cost) transport of bulk 
cargoes across the oceans. 
In view of Mr. Newton’s experience in submarine design problems, his remarks on the 
difficulties inherent in providing adequate strength in such large submarines will be of 
great value to all interested in this subject, and we are indebted to him for his penetrating 
analysis of the problem. 
Table D2 
Power Calculations for Submarine Tankers 
(Body of Revolution Hull, No Parallel Body, G, = 0.60; L/D =°7.0) 
Deadweight (tons) 18,750 56,250 93,750 
a 
0.530 
H. Lackenby (British Shipbuilding Research Association) 
I should like to make a few general remarks on the strength of the author’s conclusions, 
especially as I have since ascertained that they have a bearing on remarks I made on Dr. 
van Manen’s paper on Monday which touched on the same subject. As I said at that time, 
*F, H. Todd, “Submarine Tankers,” Shipbuilding and Shipping Record, Aug. 21, 1958. 
