Submarine Cargo Ships and Tankers 367 
the surface it has about the worst possible shape for good performance. The maximum speed 
under these conditions would probably be quite low, and if the approach to the terminal 
ports runs for long distances over a continental shelf or similar shallow water, this could 
add appreciably to the time of passage and so offset to some extent the better submerged 
performance. Such a large craft would be exceedingly difficult to manoeuvre in shallow 
water, and would be quite unwieldy at the terminals, and especially if made of light 
scantlings would be liable to serious damage and during berthing operations would need the 
assistance of tugs. In common with nuclear propelled surface ships, it would also be nec- 
essary for the port authorities to monitor continually for radioactivity and to maintain the 
equivalent of a fire-fighting service to give warning and to cope with any such accident. 
Even voyages under ice can be fraught with considerable dangers other than those of navi- 
gation. According to information resulting from the voyage of the NAUTILUS, the ice over 
the North Pole is some 9 to 13 feet in thickness but with occasional ridges penetrating some 
100 feet below this. In addition, from time to time icebergs were met with which were 
imprisoned in the surface ice and reached no less than 1000 feet below the surface. The 
use of a polar route into the Pacific is also subject to the limitation that water in the 
Bering Straits is only some 150 feet in depth. It is obvious that extremely careful naviga- 
tion would be called for to cope with such hazards. 
CONCLUSIONS 
The general conclusion which can be drawn from all the above evidence is that sub- 
marine cargo ships and tankers of circular cross section could be designed to compete with 
surface ships of the same deadweight as regards their power requirements, especially when 
one takes into consideration the effects of rough weather, from which the submarine would 
be immune. Such submarine ships would have excessive drafts, however, and if this is 
avoided by using elliptical sections, then the submarine’s superiority soon disappears. 
However, up to such speeds as those for which an economical surface ship can be designed, 
say of the order of 25 to 30 knots, the capital cost of the submarine, of the necessary dock- 
ing facilities, and of the provision of offshore terminals could not at present be justified on 
economic grounds. At the very least it would be necessary for a consortium of owners to 
combine in the building of terminals and dry docks for common use before a fleet of such 
submarines was put into service. At higher speeds, above 30 knots, the submarine begins 
to have very appreciable advantages as regards power, but of course at these high speeds 
the price to be paid in terms of fuel consumption is also high and the propelling machinery 
would begin to take up more and more of the volume of the ship, thus reducing her dead- 
weight. Whether such ships would be a good financial proposition or not would depend 
on the interplay of capital cost, insurance, maintenance, fuel and operating costs, the 
freight rate obtainable for oil or other bulk cargoes, and the route on which the ship is 
employed. If this were between the Middle East and the United Kingdom, for example, a 
submarine tanker of circular section of anything greater than about 25,000 tons dead- 
weight would be unable to use the Suez Canal in its present form. The economic advan- 
tages of large size in the carriage of bulk cargoes could therefore only be realised in 
this trade so far as submarine tankers are concerned by routing them around the Cape, with 
all the attendant disadvantages. These would not, of course, enter into other routes, such 
as Venezuela to Europe. The first marine nuclear propulsion plants will certainly be 
expensive, but the ingenuity of the engineer will undoubtedly reduce these as time goes on. 
Nuclear fuel costs, which at present are perhaps twice those of conventional fuels will also 
come down in the course of time and with the more widespread use of atomic energy in 
other fields. 
