PBY Catalina Thermos message?

"At the begining of the movie, why did the did the Catalina throw a message stating "running low on fuel, send help" to some survivors in a small boat? How could they help? Why not radio for help, since they radioed the position of the survivors?"

exactly that's what they meant by "help". they sent the submarine back to them.

"It is a flying boat, why not land and pick up the survivors yourself."

that's what they meant by "low on fuel" - they obviously didn't have enough fuel to land and start again AND make it home.

"Or at least hang out with them if your low on fuel, then there is only one target to search for, not two."

i don't think "low on fuel" means "we're going to crash this plane some few miles from here".

"Also, anyone know if Catalinas were used in the Atlantic? I thought it was only the Pacific theatre. Fun movie."

wikipedia can answer this question for you. it says there that "Catalinas were the most extensively used anti-submarine warfare (ASW) aircraft in both the Atlantic and Pacific Theaters of the Second World War".

Catalina were used by R A F coastal comand along side Short Sunderland flying boats in the North Atlantic .
In fact it was an RAF Catalina that found and shadowed the Bismark and the Prince Eugin when they attempted to give the Royal Navy the slip after sinking H M S Hood and before H force that sailed from Gilbrator could be sent to intercept them .
Flying examples of Catalina can still be seen in R A F colours at airshows in britain throughout the summer

I thought the opening shot of the Catalina from above was the best moment of the film! However, I enjoyed the film.

However, three things puzzled me:

1. Where in mid-Atlantic is it shallow enough for a submarine to sit on the bottom?
2. Were grappling hooks used by the Germans in the Atlantic to snag submarines?
3. The German Cruiser would not really be a threat to the submarine as it is not an anti-submarine ship (like a Frigate or Corvette). Why then did the submarine not attack and try to sink it?

Answers please on a postcard..........

Flying Boats could not land in all sea conditions. If the wave heights were too great the plane could crackup on landing. In reality flying boats are going to land/take-off in sheltered water like a bay, river or lagoon.

Plus, if they were able to land and had insufficient fuel to return, a rescuing ship is not likely to be carrying Av-gas to fill-er-up. You probably lose the aircraft, crew & the survivors. Not much of a rescue.