20 O. H. Oakley 
In the course of exploring the feasibility of this concept a number of interesting prob- 
lems arose. The speed was low, as expected, but model tests showed that the vertical 
location of the center of resistance varied considerably with speed. This caused substan- 
tial changes in running trim. The form was also highly directionally unstable as one might 
expect. 
Natural heave periods were calculated which indicated supercritical heave motions in 
practically all seas. No tests were made, however. The practicability of the concept is 
admittedly questionable. For instance, consider the problem of taking the ship in and out 
of harbors. The only apparent way to do this would be to provide ballasting arrangements 
to permit the ship to be brought to a horizontal position. The problems of reorienting through 
a 90-degree angle are all too obvious and painful, but not impossible. 
Catamarans (Planing and Displacement)—The yachting and small boat magazines have 
had many articles praising the sea-keeping characteristics of planing catamarans. This was 
all qualitative information. A testing program has been initiated at the David Taylor Model 
Basin to develop quantitative effects. There are no results at this time. This configuration 
has promise of allowing planing in relatively high waves, a characteristic that has not been 
attained with conventional planing craft. Structural problems will require careful attention. 
Hulls of Minimum Wave-Making Resistance—Theory by Weinblum, Martin, Kotik and 
others have developed waterline shapes that should produce minimum wave-making for a 
given Froude Number. In the speed range of interest, a Coke-bottle form appears to be 
optimum. As this involves the danger of flow separation, tests are being formulated for 
comparison of model and theory. Motion tests are planned for the future. If the model tests 
check the theory, feasibility studies of practical ships will be made to determine applica- 
tion possibilities. 
DEVICES TO INCREASE THE PERFORMANCE OF CONVENTIONAL SHIPS 
To Increase Speed 
In addition to unusual hull forms, there are various devices by which high speeds may 
be obtained. One such means might be boundary layer control to reduce frictional resist- 
ance. This could be accomplished by sucking off the boundary layer at various places 
along the length of the body. The objective would be to maintain laminar flow; this, ideally, 
would reduce frictional resistance to about 15 percent of its normal amount. The problem 
areas are: How much power is needed to suck in the boundary layer? If the boundary layer 
is drawn off through a porous outer shell, how can clogging of the pores by marine life be 
prevented? If slots are used, what should their size, shape and location be? 
Another possibility is to enclose the body by a gas. Ideally, this would reduce the 
frictional resistance to about 15 percent of its normal amount. The major problem here is 
the stability of the gas film. If the gas goes into bubble form, experience has shown that 
resistance is only slightly decreased. 
A third method would be to use a coating that absorbs the energy in perturbations in 
the water. A theory, as yet unpublished, by Boggs of the United States Rubber Company, 
indicates that a coating could be devised to maintain laminar flow up to very high Reynolds 
numbers. 
