The ships need to be equally destructable. This in part means materials need to have a balanced blast resistance and be flammable. You also can’t currently put attachables on certain sides of blocks. (ladders, torches, no doors at all) That might be fixed later by the plugin authors. The spacing of the TNT needs to be enough to create the occasional chain reaction, but not too close that it’ll do it most of the time. The larger the size (mostly length and height) the longer it takes to regenerate. A shorter mast would be nice — probably should shorten the current ones. Any island should not have material going below the bottom of the ships for the same reason.