Mark, >What systems, manufactures, models, other considerations would anyone >recommend or even not recommend? We just bought two Marine Air 16kBTU Vector Compacts. Personally I think Marine Air has passed Cruisair in their engineering, depth and quality - tho I know several happy Cruisair customers too. Pluses are very compact size, rotary compressors (quite, reliable). Their customer service has been first rate. For info contact Blake Liebeskind, For info contact Blake Liebeskind, liebeskb@marineair.com. Blake handles international, but will put you in touch with the right US people. >How does one determine what size btu would be sufficient? Both vendors will supply load estimating guides. The simplest method is Total Load (BTUs) = 17 x volume (cuFt) + 150 x window area (sqFt) for each zone. A more accurate method uses surface area instead of volume, and accounts for the R values of each surface - the Carrier HVAC program uses this approach. Cheers, Steve ------------------------------------------------ Stephen C. Darden Email: darden@xtra.co.nz Adagio Marine Ltd. Fax: 649/4037-213 P.O. Box 161 Voice: 649/4037-801 Russell NEW ZEALAND