I would like to identify a movie I saw maybe 30 years ago.
It is about a stubborn WW2 captain who is demoted and put in charge of an old tugboat in some backwaters. He still tries to make the best of it and turns the boat and apathetic crew into a formidable war machine, finally seeing some action.
There is a particular scene where, chronometer in hand, he puts the boat and crew through extreme torpedo evasion manoeuvre drills, until the crew is able to do it in under a certain amount of time.
It's probably in color and has similar style and contents as "Mr. Roberts" with Henry Fonda as captain, or "Operation Petticoat" with Cary Grant commanding a decrepit pink submarine. I checked the filmography of various late 50's early 60's Hollywood Navy captain candidates such as Fonda, Grant, Stewart, Wayne and Holden without luck. This has been bothering me for 30 years..
Possible addition 1: the captain has the boat nearly dismantled to the crew's dismay, so as to lighten it for performance reasons. This memory could be mixed with the German John Wayne captain who cannibalizes his own ship for extra fuel to escape the allied posse in another great movie.
Possible addition 2: later in the film the tugboat narrowly escapes a couple of torpedoes, though this scene is very common in war movies. Possible inconsistency here: why would a sub waste two torpedoes on an old tugboat?
It's not "Away All Boats" and it isn't "The Cruel Sea", either.
EDIT: It's not The Key (1958), Run Silent Run Deep (1958)