Following Archimedes' principle we can pre determine whether a body floats or sinks knowing weight and volume.
I made two calculation sheet to verify this using two simple geometrical shapes. A cylindrical and a square boat.
In the more complex you can decide type and number of coin their arrangement in square rows, the gap between coins and the formulas tell you the dimensions of the boat to print and the amount of diving
there is also a simplified version where you have to insert manually all the data and also you get the amount of diving
I print the two boats in PLA nozzle 0,4 with a wall tickness of two