Submarine Cargo Ships and Tankers 365 
legislation. It is probable that these two items together would amount to not less than 25 
percent of the displacement. Although such a vessel would not have to carry bunkers, there 
would be little if any saving of weight in this respect since the shielding for the reactor 
would be of the same order of magnitude. All these considerations add up to the fact that a 
submarine cargo ship or tanker would require considerably greater displacement than a sur- 
face ship to carry the same deadweight. 
Any nuclear propelled ship will call for a much greater skill in the engine room crew 
than does a conventionally powered ship. If in addition the nuclear propelled ship is also a 
submarine, then the navigating crew must also be very highly skilled and undergo long peri- 
ods of training comparable with those of similar navy crews. The additional cost of this 
skill could be considerable and may be an important factor in the overall comparison. 
At least in the single-screw designs it will be necessary to have some means of auxil- 
iary propulsion such as motors and batteries or diesel engines for use on the surface in an 
emergency. If a single-screw submarine were designed for use under ice, it would seem 
almost essential to have electrical auxiliary propulsion since in these circumstances it 
would be impossible to bring the ship to the surface until she was clear of the ice. In the 
case of a twin-screw ship with two entirely separate propulsion plants, auxiliary propulsion 
could probably be dispensed with. 
Considering in more detail the operation of the circular and elliptical submarines and 
the surface ships for which the estimates of power are shown in Figs. 9, 10, and 11, we see 
that the circular section submarine requires a lower power than either the surface ship or 
the elliptical submarine. However, we see that the advantage is not large unless we con- 
template speeds of 25 or 30 knots and it is a question of the economics of the oil industry 
whether it is justifiable to carry a commodity such as oil or indeed any other nonperishable 
bulk cargo at such high speeds. It is not proposed here to enter into these economic ques- 
tions, but it may be sufficient to point out that these will vary from time to time, as wit- 
nessed by the fact that during the Suez crisis the cost of transporting oil via the Cape rose 
to £19 per ton as compared with the normal freight rate of £2 per ton via Suez. In addition, 
it has been estimated that the capital cost of a submarine tanker would be of the order of 
twice that of the equivalent surface ship [7,8]. It would appear, therefore, that the advan- 
tages from a commercial point of view would not be large enough at commercial speeds to 
counteract the increased capital cost of the submarine and the increased costs of mainten- 
ance, crew, insurance, and the large expenditure which would be necessary for research and 
development before such a ship could be built. Beyond these operational problems is the 
further one that a circular hull submarine large enough to justify nuclear propulsion and 
competition with similar surface ships would have a very large draft and would require new 
building facilities, new dry-docking facilities, and new terminals. It would also be very 
limited in respect of the world ports in which it could be accommodated and would certainly 
not be able to pass through the Suez or Panama Canals for many years to come. If sucha 
ship to carry oil from the Middle East to Europe had to go via the Cape, then this would far 
outweigh any advantages it might have in regard to lower power requirements. 
If we restrict the draft of the submarine to a figure comparable with that of the equiva- 
lent surface tanker, then we are forced into accepting a submarine having elliptical sec- 
tions. As an extreme case the figures have been calculated for such submarines of different 
deadweights having a beam/draft ratio of 4:1 and the power curves for these have been given 
in Figs. 9,10, and 11. It is at once seen that from a power point of view, even after making 
some weather allowance for the surface ship, there is no longer any overall benefit to be 
derived on the basis of power. If the thesis is accepted that for a submarine tanker the 
structure carrying the oil can be of light scantlings, then there would not be a very great 
646551 O—62——25 
