Size, Type, and Speed of Ships in the Future 39 
For displacement ships (cargo), the increase in ship speed will stop between 20 and 25 
knots. Above these speeds, the nuclear powered submarine will get its chance (future). The 
maximum draft will be limited to 10 to 11 m by harbors and docking facilities. 
For submarine vessels (merchant ships), the limitations in horsepower per shaft and in 
available space for engines, especially athwartships, results in a maximum deadweight for 
submarine of 40,000 tons at a ship speed of 37 knots. 
For hydrofoil boats, extremely high speeds such as 60-80 and 100 knots seem to be 
obtainable. The displacement of such high speed hydrofoil boats will be restricted to about 
100 tons or less. 
For GEMs, displacements greater than 100 tons combined with extremely high speeds 
(100 knots) lead to serious construction and propulsion difficulties. Propulsion in water 
seems to be attractive for a seaborne GEM. 
DISCUSSION 
R. N. Newton (Admiralty Experiment Works) 
My remarks bear upon the papers presented by both Mr. Oakley and Dr. van Manen and 
concern those patts which deal with hydrofoil craft and hovercraft. 
The considerable experience already acquired with hydrofoil craft leaves no doubt that 
one clear advantage of this type of craft over the orthodox displacement or planing types is 
the ability to maintain higher sustained speeds in a seaway. The same advantage, associ- 
ated with higher speeds still, is being claimed for the more recent hovercraft or GEM. 
One question which has yet to be resolved, however, is the extent to which this partic- 
ular advantage applies; that is to say, it is necessary to qualify the words “in a seaway” to 
cast a true comparison with, say, the planing craft. The moral can be pointed, in humorous 
and yet serious vein in the present context, by this quotation from the writings of Hilaire 
Belloc: 
“The water-beetle here shall teach 
A sermon far beyond our reach; 
He flabbergasts the human race 
By gliding on the water’s face 
With ease, celerity and grace; 
But if he ever stopped to think 
Of how he did it, he would sink.” 
Whatever form the humanly conceived “water-beetle” may take, I submit the time has arrived 
to think seriously as to what state of sea would force it to stop and whether it would, in 
fact, then sink. 
Assuming no breakdown of the engines to occur the craft can be forced to land on the 
sea from two principal causes: 
