I viewed the extended version on DVD.
I can not remember how many minutes that it runs.
Also, I watched the DVD bonus feature showing Director Wolfgang Peterson commenting on the scenes.
The scene wherein the Captain and the First Officer (I think) exit the sub and are transported up the cliff of Gibraltar (I think) to an elegant party reminds me of the stop which the "Apocalypse Now" crew made at a the rubber tree plantation on the way up river to attack Colonial Kurtz.
The "Das Boot" scene which I remember best occurs near the beginning of the film at the party the evening before the crew sets out. A drunken crew member unloads his sidearm at someone running up the set of stairs to the second floor. The plaster exploding outward from the bullet holes in the wall just behind the person running up the stairs is a nice touch.
As an aside, I have seen video of Director Peterson being interviewed in the past ten years. He strikes me a a good-natured person.