Unfortunately the copy of the movie that I got from the library turned out to be very old and poor quality and the screenshots that I made pale in comparisnment to the pictures provided by good gentlemen of BOB-MA Developer Group.
However I still think that the buoys were equipped with rescue radios, otherwise what are the things sets on the edge of the top structure in front of the mast? To me they look exactly like radio antennas.
I also have to admit that I was wrong about the shape of the buoys, although such a mistake can be easily made if all one has to look at is an old b&w movie.