Attacking a heavily armored large cruiser

How could Spearfish-delivered bombs reach a B-65 large cruiser's magazines through heavy deck armor?

It would likely require multiple attacks, with initial hits causing fires and damage before later bombs had a realistic chance of penetrating the deck.

Delayed fuzes and repeated strikes are more plausible rather than expecting one 1,000-pound bomb to solve the problem. Multiple hits could first damage the superstructure and cause fires, producing a mission kill. Further attacks would then have a better chance of defeating deck protection.