You see, that if you call it heave the next instance the ship is changed this direction. So, that the motion.
Company will surge and heave.
No no, when you say the ship is heaving 4 meter, what do you mean it is see, in this case the heave axis is continuously changing to this side, this side, this side, this side like that going, so which one is you call heave, when you say 4 meter is on, this 4 meter, because it is not fixed here it is continuously changing.