Hydrofoil Size and Seaworthiness 197 
{ 
“he 5 ) - V Gal?) , daly? 
-) 0s 40 13 
wh, — 
Fig. 4. Amplitudes of forced vibrations for various degrees of damping 
BEHAVIOR OF THE CRAFT 
Conceming the course of a hydrofoil craft relative to the waves, experience has shown 
two conditions to be of decisive importance for its seaworthiness. The first occurs if 
y = O, i.e., on a following sea. In that case, the extreme value of w plays a dominant role. 
Figure 5 shows the influence of the orbital motion of water particles in a following 
sea. This orbital motion creates a moment which tries to pull the nose of the craft down. 
Fig. 5. Influence of the orbital motion of water particles in a following sea 
