Operation Pacific.

During WWII, Duke E. Gifford is second in command of the USS Thunderfish, a submarine which is firing off torpedoes that either explode too early or never explode at all. It's a dilemma that he'll eventually take up personally. Even more personal is his quest to win back his ex-wife, a nurse; but he'll have to win her back from a navy flier who also happens to be his commander's little brother.