So ,the ship is treated being treated remember as a rigid body. This full body is not taken obviously in our study and this also largely true because ,is you take it flexibility it is going to be only a much smaller amount in term of displacement; for example if you take a elastic deformation maybe about one feet maximum whereas ,the heave motion may be few meters ,So ,from the point of view of so ,it is important from structures load point of view beside , I did not mention also structural load the ship has to be designed to you know withstand this wave lose, but the point here is that, we have studied ship motion as a rigid body whereas, a practical person would like to know this sought of stuff much more, because they are the one that is actually, effecting you designed. Now it can be found out that all if this can be are a function of that fundamental 6 modes all of this are function of that which means all of this can be derives from fundamental those motions that we completed