342 F. H. Todd 
and passenger-carrying hydrofoil craft are now in use in a number of sheltered waters. It is 
natural that efforts should be made to extend this principle to larger ships, but the difficul- 
ties in the way are considerable —the foils and their supports become more massive and 
heavy, detracting from the deadweight carrying capacity, they are a source of trouble due to 
the large draft they cause when the boat is on the surface coming into port, and since they 
are essentially high speed craft the large powers necessary must be transmitted from the 
hull to propellers a long way below the hull. Studies of such designs are going on, and we 
shall doubtless see much larger craft of this type built for specialised services, but their 
use for carrying the bulk cargoes of the world seems unlikely. Moreover, such boats still 
have to contend with the ocean waves on the surface of the sea, and therefore for any given 
size have limitations as to the sea state in which they can operate. By going below the 
surface, both wavemaking resistance and bad weather can be avoided altogether, and with 
the advent of nuclear propulsion the naval architect for the first time is in a position to 
seriously contemplate such a procedure. The use of nuclear reactors as a source of heat 
has freed the ship from dependence on the atmosphere and made possible the true submersi- 
ble, which would spend all its seagoing time deeply submerged and only surface near the 
ends of its voyages. The hull can therefore be shaped for minimum resistance under deep- 
submerged conditions, with little concern as to its surface performance. The benefits to be 
gained are, of course, the elimination of surface wavemaking resistance, the reduction of 
form resistance to a minimum by streamlining the hull, and escape from the effects of bad 
weather. 
The availability of nuclear propulsion for ships, as in the case of other new inventions, 
has led to a search for useful and practical applications. So far as the navies of the world 
are concerned, there is no doubt as to the value of nuclear propulsion in submarines to 
enable them to remain submerged almost indefinitely and in other ships in order to maintain 
fleets at sea for long periods without refueling. Nuclear-propelled submarines, apart from 
their military use, could be of extreme value for the delivery of fuel and supplies to com- 
batant ships or to beleaguered islands or ports. From the national safety point of view, 
also, submarine tankers and cargo ships would be of inestimable value because of their 
relative immunity from enemy attack. A considerable number of military nuclear-propelled 
submarines are now in commission and it may well be that the first nuclear-propelled sub- 
marine supply ship will also be built by one of the navies of the world. The Russians, 
because of their particular geographical problems, have made the first application of nuclear 
propulsion to a surface ice-breaker which can, as a result, stay at sea for long periods to 
keep the lanes open throughout the winter. 
The spectacular voyages of the USS NAUTILUS and SKATE under the North Pole in 
1958 have also shown that submarines can be navigated for long distances under water 
without having to surface for sights of the sun or stars. This fact has led to much specula- 
tion regarding the possible use of such ships on routes which are closed by ice for part or 
all of the year. 
As we shall see later, the submarine ship must operate at fairly high speeds to show 
material advantages over the surface ship, perhaps 30 knots or above. This fact may have 
some attraction to passengers who suffer from travel sickness but enjoy the restful atmos- 
phere of a ship, and limited passenger accommodation may become a feature of such vessels. 
True, the passengers would not see the sea, but neither do many travellers today, who 
divide their time between dining saloon, bar, and cabin, and there is certainly no less to see 
than in the upper atmosphere! 
When we come to consider such ships for commercial use, however, a number of operat- 
ing problems are introduced, and it is the purpose of this paper to review these and, it is 
