Character mistake: While the engine room is flooding, Stepanik tries to put a jubilee patch on the pipe by walking towards and deflecting the water. While it looks cool for the movie, it is definitely not the correct way to apply this type of patch.
Down Periscope (1996)
1 character mistake - chronological order
Directed by: David S. Ward
Starring: Bruce Dern, Kelsey Grammer, Rip Torn, Rob Schneider, Harry Dean Stanton, Lauren Holly
Genres: Comedy
Factual error: Most uniforms in this movie are worn incorrectly. Between wearing belts incorrectly, not wearing ribbons on dress uniform (shore patrol), female hair regulations, shoes, and having ribbons in the wrong order it's like they didn't even try.
Pascal: Buckman! There was a fingernail in my food, you fat-ass moron! Yesterday, it was a band-aid!
Buckman: I'm sorry, sir. The band-aid was holding the fingernail on.
Trivia: Tom Arnold turned down the role of Lt. Com. Dodge to play the lead in "McHale's Navy."
Question: Would pouring whiskey into the tank have really thinned down the mix, giving the submarine more speed?
Answer: Adding alcohol to gasoline can lower the fuel's viscosity, thinning it to flow more easily. It can only marginally increase an engine's speed and power.
raywest ★
But the question was, would it have actually increased the sub's speed?
Thinning the fuel mix would not increase energy or performance, so it would not make the submarine faster.
Technically, yes, diesel with alcohol burns better. As for what happened in the movie: no. Whiskey is not alcohol; it's water with alcohol, and the water reduces the flammability a lot. Also, a sub has fuel tanks that hold tens of thousands of gallons; adding a few ounces of whiskey will not have any effect at all.