I had a gallon of this stuff many years ago.... got it from an advertizer in Hemmings Motor News...
For people who live in cold areas that discover rust this seems like something one could use until spring weather allows normal rust methods which require warmer temperatures to be applied.
http://www.retro-uk.com/fertan.htm
This submarine project was included in the literature which came with it.
http://www.submariners.co.uk/Boats/Barrowbuilt/Beginning/
http://www.google.com/search?hl=en&lr=&q=fertan+submarine+british&btnG=Search