Just a small expansion of my free body physics sim to demonstrate that it can work for floating objects. Buoyancy and drag forces are applied to the point masses. Press 1 2 or 3 to load an object. Click and drag to move the object around. Of course, there are some limitations to the point mass method. The object might not find an equilibrium if they are too sparse. This could be solved by using regions like circles or polygons to determine the proportion that is submerged. It would also make it possible to simulate water entering a hollow vessel causing sinking.
