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: When the submarine rises in the waters of Norfolk and you see Norfolk in the background, there is one blatant problem. There are NO mountains in Norfolk. Most of Norfolk, Virginia, is below sea level.
Pascal: Jesus, Buckman! This stuff has been on the Stingray since Korea! This can expired in 1966!
Buckman: What's the matter, sir? It still tastes like cream corn.
Pascal: Except it's deviled ham.
Trivia: In the scene when Lauren Holly, gives Kelsey Grammer, a kiss, her hitting her elbow was not in the original script. She really did hit her "funny bone" before walking off camera. The director had decided to keep it in the movie so they had to film an alternate shot of Grammer, laughing when it happened.
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.