Torpedo

Submarines fight with these. A torpedo runs straight ahead from the tube, so it is best against something that isn't dodging: a boat moored at a monument dock, another sub hovering while its crew loots, a RHIB idling near an oil rig.

Against a moving target at range they mostly miss. There is no guidance, so close in from below or behind, line up, and fire when the boat can't turn away in time. A sub crew that wastes torpedoes on long shots ends up surfacing with an empty tube.

A batch of torpedoes takes a metal pipe and gunpowder, which hurts early in a wipe when both are going into guns and ammo. That is why most groups only build torpedoes once they really plan to hunt on the water.

Divers are the wrong target. A swimmer is tiny next to a straight-running torpedo, and a teammate in the water with speargun spears handles them far better.