I think it was the mid 70s, people were stranded on a boat and one was the devil, the last seen was a man hanging from the mast and a chopper picked up the survivors and the coast guard radio in and said it was a lady. The lady on the chopper started laughing real evel and turned into the devil. He tried to get the pilot to give him and his family there soul and he didn't and crashed into the ocean. The last scene was the devil in the lady disguise getting rescued. Any help?

Satan's Triangle (http://www.crankedoncinema.com/reviews/1975/satan039s-triangle)