Wasp and the logic of a large submarine torpedo salvo

I-19 fired a six-torpedo spread at Wasp. Three weapons struck the carrier, one hit the destroyer O'Brien, another hit the battleship North Carolina, and only one missed every ship in the formation. That distribution helps explain why British T-class submarines carried a ten-torpedo bow salvo: more weapons could threaten ships beyond the intended target as the spread crossed a formation. The further damage a ten-torpedo spread might have caused is a counterfactual, but the actual five hits still show why some submarine designers valued a large salvo.