le Ee re 
368 F. H. Todd 
So far we have restricted ourselves to a comparison between nuclear propelled surface 
and submarine ships. The case for the submarine would be even less favourable at this 
time if we were to compare it with a conventionally propelled surface tanker. The British 
Shipbuilding Research Association has compared surface tankers having respectively con- 
ventional and nuclear propulsion plants and has shown that even on the assumption of 
economic parity between capital and fuel costs there is no commercial attraction in 
installing in a surface tanker a nuclear plant of higher power than the conventional ones 
being installed at present [9]. It has also been shown, in the case of a tanker of 65,000 
tons deadweight with 25,000 shaft horsepower employed on the Middle East-United Kingdom 
route, that while the cost per ton of transporting oil via the nuclear ship might be within 
15 percent of that for the conventional ship, the cost for the nuclear ship begins to rise 
again at speeds above 17 knots [10]. This means that from the point of view of economy 
there is really no inducement to fit higher powers in nuclear ships than are at present fitted 
in conventional ships. The greatest commercial incentive for submarine ships at the 
moment would appear to be their use on special routes where surface ships cannot be used 
and on which there might be the attraction of making special profits. One such route which 
has been mentioned on many occasions is that from Canadian ports carrying out ore in 
winter underneath the ice, and another has been the suggestion put forward in the London 
Times that by going under the polar ice it is possible to halve the distance between London 
and Tokyo [8]. 
Leaving aside economic questions, there is no doubt as to the extreme advantage of 
having such craft for military use and for the transport of valuable cargoes in wartime. It 
may well be that some government will build a craft of this type very soon, both for its 
military potential and national prestige, and to gain experience in the operation of such 
ships. Something of the magnitude of the tasks facing the designer of such submarine cargo 
carriers as we have been discussing may be realised when it is recalled that the largest 
submarine built to date is the USS TRITON, which has a length of 447 feet, a displacement 
of 5900 tons, and two nuclear reactors. This is the longest and most powerful submarine 
yet built and it is a very long way to go from this to tankers of the order of 60,000 or 
80,000 tons. Although the tasks are formidable, there is no doubt as to the challenge they 
present and the extreme interest which they engender in the mind of the designer. Using a 
completely submerged hull of ideal form, the propeller designer is presented with wonderful 
opportunities of realising his ideal propeller—a circumferentially uniform wake, the chance 
to apply impeller theory to marine problems, and the knowledge that at such deep depths 
cavitation will no longer be a paramount inhibitor always looking over his shoulder. To the 
hull designer, the challenge will be to eliminate all possible sources of parasite drag by 
attention to hull form, appendages, and smoothness of surface and to ensure adequate direc- 
tional stability and control, while tantalisingly in the offing will be the lure of someday, 
somehow, achieving laminar flow over some of the hull surface. Inevitably progress will be 
made only by small steps, and the development of a successful submarine cargo ship or 
tanker will involve many years of research and development and much money. From the 
scientific and technical point of view, such a vessel presents a great challenge to the naval 
architect and marine engineer, who will doubtless continue to dream of the possible solu- 
tions until the day comes when they are given the opportunity to translate their ideas into 
reality. ; 
