DESIGN AND OPERATING PROBLEMS 
OF COMMERCIAL HYDROFOILS 
H. Von Schertel 
Supramer A.G., Lucerne, Switzerland 
Development of modem means of transportation undoubtedly trends to- 
wards a progressive increase of speed in combination with an improved 
riding comfort. Speed on the water is still far behind the speeds already 
achieved with road or rail vehicles and aircraft. 
Conventional types of watercraft cannot attain the speed of land 
vehicles under economically acceptable conditions. The solution of the 
problem by means of the hydrofoil boat is examined and the specific 
qualities are discussed by which the requirements are fulfilled. 
The paper then deals with the fundamental physical aspects of the foil 
system as the most important design problem, and comparison is made be- 
tween the surface-piercing foil and the fully submerged foil in relation to 
drag-lift ratio and behavior in a seaway. The section ends with a review 
of the practical adaptability of these two basic foil systems. 
In the second part of the paper the commercial application of hydrofoil 
boats is discussed. Technical data are given about the types which are 
already being operated in regular passenger service. After a short review 
about the introduction of the hydrofoil boat in public transportation, 
follows an enumeration of the various existing hydrofoil passenger lines. 
Finally the economic transportation problems are dealt with and data 
are given about the profitableness of hydrofoil passenger services. The 
field of application of commercially operated hydrofoil craft within the 
framework of modern communications and their limitations as regards 
speed is investigated. 
INTRODUCTION 
Development of modem means of transportation undoubtedly trends toward a progressive 
increase of speed in combination with improved riding comfort. Considering the progress 
achieved in passenger vehicles on road, on rail, and in the air from their first use in public 
service until the present, one finds that their speeds have increased about tenfold. The 
first railroad between Stockton and Darlington inaugurated in 1825 attained a speed of 10 
miles per hour, while European express trains nowadays run at top speeds of 100 mph. The 
first serviceable automobiles reached about 12 mph, which in the course of time was stepped 
up in normal passenger cars to 120 mph. The passengers of the first commercial aircraft 
were carried at speeds between 60 to 75 mph. Today we cross the Atlantic at nearly 
600 mph. © 
Conditions in waterborne transportation are very different. Already in 1860 the “Great 
Eastern,” the largest vessel of its time, attained a speed of 14.5 knots whereas the cruising 
speed of the fastest passenger ship of today, the “United States,” surpasses this hardly 
2-1/2 times. On inland waters the increase of speed has been by no means greater. The 
233 
