Back in the day, a TV-film called Ironclads was shown on telly. It being back in the day, I had to record it on crappy old VHS (yes, shock horror, there was no digital recording in that bygone era). It was a somewhat cheesy American Civil War melodrama but the highlight was its depiction of the famous Battle of Hampton Roads, the world's first ironclad versus ironclad ruck. The miniature effects were very well done (and shit all over cgi IMHO) and were, perhaps surprisingly for a Yank fillum, shot in Blighty!
Ironclads, sadly, is not available on DVD (I still have the off-air recording but haven't digitised it yet). However, someone has edited out the battle and bunged it on YouTube (it doesn't, sadly, include some earlier scenes when the Merrimack/Virginia first attacks the blockading Northern warships):
In June 1992, Model Boats magazine published a five-page article about the making of the miniature battle sequences. I've now scanned this fascinating piece and you can read it below (click on the images for biggitude).