I'm constructing a diorama of a ship sinking, and I haven't been able to find any details on the physics behind it. I'm an art student, so my knowledge in physics is limited to what I read here and in a few books at home. I'll most likely construct a fish tank that is 4'x1'x1' to contain the water and toy ship. My question is to what formula I would use to determine how heavy to make the toy ship. Is it just a scale issue? Where I could just use the size ratio to figure out the weight? If I go that route, will the amount of water or the size of the tank affect the rate at which it sinks? Also, I'll be using an air compressor hose to attempt to raise the ship while it is sinking. How does one determine how much air can raise a certain amount of weight underwater? Thanks!