WAVE FORCES ON A RESTRAINED 
SHIP IN HEAD-SEA WAVES 
Odd Faltinsen 
Det Norske Verttas 
Oslo, Norway 
ABSTRACT 
The exact ideal-fluid boundary-value problem is 
formulated for the diffraction of head-sea regular 
waves by a restrained ship. The problem is then 
simplified by applying four restrictions: 1) the bo- 
dy must be slender ; 2) the wave amplitude is small 
3) the wave length of the incoming waves is of the 
order of magnitude of the transverse dimensions of 
the ship ; 4) the forward speed is zero or it is the 
order of magnitude e V2-a ; O<a<1/2, where e€is 
the slenderness parameter. 
The problem is solved by using matched asympto- 
tic expansions. The result shows that the wave is 
attenuated as it propagates along the ship. The re- 
sult isnot expected to be validnear the bow or stern 
of the ship. 
The experimental and theoretical pressure distri- 
bution along a prolate spheroid have been compar- 
ed. The predicted attenuation of the peak pressure 
is very well confirmed by the experiments. In ad- 
dition, theory and experiment agree that the peak 
pressure near the ship generally leads the Froude- 
Kriloff-pressure peak by 45°. 
I, INTRODUCTION 
Thereisa growing interestin finding the pressure distribution 
along a ship due to waves. Uptonow one has mainly concentrated on finding 
motions, shear forces, bending moments and torsional moments along 
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