If you select:
Modules -> Sites -> Minefield -> Naval Mines (bottom) you get an Error, and it is not working at all.

for the Moored Mines:
Modules -> Sites -> Minefield -> Naval Mines (Moored) it creates the Minefield, but the Mines are way to high. They stick out of the water and are not beneath the surface. You also can't colide with them. {F18023}