There's a marine refrigeration guy in Ft. Lauderdale who has a book that answers a lot of refrigeration size and use questions that I see posted on the list, he's Richard Kollman. I'd give you his website but the wizards at BellSouth DSL are down and have been since Saturday, I've got email but no web. Kollman's site also is very instructive but his book is really easy to understand. John Reitzammer Willard 30' Cutter (Trawler built inside my sailboat)