Question:

I am trying to do damaged stability for a hopper-dredger. This vessel has large hoppers, which are open at the tops. I am wondering what the best way to model them in GHS is. Can I model them as tanks, and just not specify the tops of the tanks? If I do this, will the contents spill if the ship heels to such a degree that the contents would spill from the top, or would GHS assume a top?

Answer:

GHS always assumes a top. However you can use the TYPE command (in the GHS main program when you are running the calculations, not when building the geometry) to specify the hoppers as SPILLING type tanks. You also have to put each tank's "reference point" (using the REFPT command) at the lowest point over which the spilling is to take place. A SPILLING tank behaves as a normal INTACT tank except that the level in the tank is not allowed to exceed the height of its reference point.

It is also possible to model water over mud in the hopper. To do this you have to create two identical superimposed tanks. Load one with water and the other with "mud" having a specific gravity that is the difference between that of the mud and the water. This accurately models the two free surfaces in the hopper.