Size of RIB
Weight and power of engine
Speed
Shape of hull
Sea State
Weight of empty boat
Weight of load - and position in the boat.
Obviously a RIB sat in the marina isn't under much strain - A pwerfull heavily loaded RIB pounding through heavy seas at high speed is going to be under all kinds of strain.
Can you give some more detail as to what you are after!
The best way to discribe the forces on the hull are LOADS & LOADS. And then more!
There is no set formula as a lot of RIB builders have found out.
A well laid up hull is one that has got a heavy gel coat first. So many builders just "colour" the hull and when it comes back in a plastic bag say that it must have been used beyond its design capability when in fact it is just a poorly built boat.
