 They were not true submarines but were "semi-submersible"; when ballasted, only the smokestack and few inches of the hull were above the water line.CSS "Midge" was a "David"-class torpedo boat.CSS "Squib" and represented another class of torpedo boats that were also low built but had open decks and lacked the ballasting tanks found on the "David"s.

The Confederate torpedo boats were armed with spar torpedoes.