Originally Posted by chuck53
For a 30 footer, 12k BTU is more than enough.
Chuck, I've seen a number of theories on sizing AC units for sailboats. When I talked to the Webasto guy at Annapolis last year he thought the 9K might be a little undersized on really hot days and recommended the 12K.
A unique thing on our boat is I have a set of removable companionway doors. That adds a lot of additional glass area compared to hatch boards.