Looks great. For one thing though it would hace great effectiveness if it was used during the normandy beach invasion while allied ships were still in the middle of the sea. The problem though i bet was that with so few of them very few would be effective, unless they used kamikaze planes filled with explosives to take out ships. Mainly fill the bottom plabe with enough exploaive charge to tear a huge whole in the ships. Though not sure when they became necessary, and were relied upon due to desperation.