Faltinsen 
the ship. But the development of the finite element technique in ship 
structure analysis has necessitated a more detailed information of 
the force distribution along the ship. 
We are in this paper going to consider the regular wave case. 
But it is to day well accepted that we can apply the principle of linear 
superposition and statistical theories to sum up the responses in re- 
gular waves of different wave lengths and headings to predict the res- 
ponses in irregular sea. 
The solution of the regular wave problem is usually divided 
into two problems. One part is the case when the ship is forced to os- 
cillate and there is no incoming waves. The other part is the problem 
when there is incoming regular waves and the ship is restrained from 
oscillating. Due to linearity the pressure, forces and moments ob- 
tained in those two problems can be superimposed to give the total 
pressure, forces and moments on a ship which oscillates ina steady- 
state condition in regular waves. 
We will here consider the case when there is incoming regu- 
lar waves ona ship which is restrained from oscillating. We will as- 
sume that the wave length is of the order of magnitude of the trans- 
verse dimensions of the ship, and that the waves are coming from 
ahead. Our goal is then to find the pressure distribution along the ship. 
The head-sea problem is up to now an unsolved problem. For the 
oblique-sea case Ursell (1968 b) found a solution but he was not able 
to find a solution for the head-sea case(Ursell (1968 a and b) ). 
Ogilvie and Tuck (1969) have considered the complementary 
problem, namely the forced heave and pitch oscillation of a ship when 
there are no incoming waves. For the zero-speed case the order of 
magnitude of the frequency of oscillation used in Ogilvie & Tuck (1969) 
is the same as the order of magnitude of the frequency of the waves 
assumed in this paper. In the forward-speed case, the assumptions in 
Ogilvie & Tuck (1969) and in this paper are different. 
Ogilvie & Tuck gota strip theory result and it is well-known 
that strip theory gives good results for a wider range of wave lengths 
than Ogilvie & Tuck restricted themselves to (see Salvesen, Tuck & 
Faltinsen (1970) ). So it is the hope that the theory presented in this 
paper also will cover a wider range of wave lengths. But it is only 
our experience that is going to tell us for how large wave lengths our 
theory is capable of predicting the pressure distribution along the 
ship. The theory predicts that head-sea waves of small wave length, 
are deformed as they propagate along the ship. Experiments seem to 
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