Very weak Das Boot clone, with ghost added
This movie was so bad. Firstly, when the movie starts it is precisely Das Boot but with less realistic people and a crappy hollywood song accompanying the ship. The first thing that came to mind was that the makers of the film loved Das Boot, but had to make an American version of it. Then they went nuts and decided to add a ghost.
The story itself is equally implausible, what idiot would target a hospital ship? That happened on the Eastern Front, but in the West noone would deliberately attack such a ship. Especially if you are on an Allied submarine in the Atlantic in 1943, I figure you would check your target for markings 10 times before firing. The way a German ship perfectly matches a Royal Navy type ship is equally stupid, weren't they targeting a commercial ship that can have 100's of types?
The setting of the movie was simply very poor. The ghost wasn't very scary either. If you like the tension of people on a submarine, with an ocean full of enemy ships above you, Das Boot remains unbeaten by far and is actually scarier than this so-called horror movie.