Here's a link to a guy that had a pretty neat camera "boat" at our national battle this weekend. http://www.madox.net/blog/2009/06/06/australian-battle-group-national-battle-meet-6-june-2009/ I'm not sure how he built it, what's in it and the tech involved, but it seemed to work OK.
Very impressive! As the photo/filmographer of the WWCC, I'll have to have my own adventure with on-the-water filming
If your photographer is interested, I have a little camera that does video and stills nice and light and waterproof, There are 2 Bismarck threads under video you can look at if you want to see and maybe try for your next outing, The sound really adds a interesting feel to the battle footage. http://ontarioattackforce.multiply.com/video/item/5/Bismark_Battle_and_sink_June_2009.wmv