I guess regular explosives would also work.

https://en.wikipedia.org/wiki/Sinking_of_the_Rainbow_Warrior

Orca's would do little against yachts of this size I'm afraid. Torpedoes on the other hand...

You could try increasing 'Infill/perimeters overlap'. Its helped me before. https://forum.prusa3d.com/forum/prusaslicer/gap-between-solid-infill-and-perimeters/