To maintain the continuity of the thread, I''ll ry to answer Mr. Kollman''s question. We have lived aboard for four years with an evaporator-type refrigeration system (water cooled BTW), both in seasonal (Maryland) and tropical (FL to USVI) waters. We have also lived aboard 4+ years now with a DC holding plate (vs. evaporator) system, also water cooled - again, in a mix of seasonal climates and tropical conditions (from N Europe to the Caribbean). For boxes of comparable size and insulation - a bit of a judgement call, I admit, but faithfully offered as accurate - I found the amp/hr consumption of the evaporator system to be twice that of the holding plate system (55-60 amp/hrs vs. 30-35). But this isn''t really about the numbers; we can see and feel the difference measurably. Evaporator boxes are typically placed near the top of the box, and it''s here where the heat is absorbed by the freon coils in the evap plates. There is no cold mass to speak of there, just those thin plates. What we notice in the warmer climates is that, the minute you open the box and the warm air has a chance to reach inside (while you''re rooting around for that tub of yogurt at the bottom...), the box temp rises noticeably and there''s nothing to address this except for the system to kick on and pull down the temp of the box via the plates again. In warmer climates, you tend to dig into the box more often and a 50% duty cycle is not unheard of, even with good ice box construction. When this happens with our holding plate system, the compressor doesn''t come on nor need to; the cold mass is not appreciably affected. I assume that it is this human variable, diving into the box repeatedly in warmer climates, that is often not represented in efficiency comparison tests...but we certainly can see it in our little corner of the world.
There are indeed a lot of good systems out there, altho'' what I find is that people are often a bit myopic about choosing systems based solely on cost or promised energy efficiency or the newest sliver of technology. I''d just encourage one to fold in ALL of the issues that - ultimately - effect one''s satisfaction with a reefer choice. Flexibility with one''s cruising lifestyle (which is why I recommended 12V systems above), whether installation requires a hole in the boat bigger than any thru-hull you''ll find in a chandelry, familiarity of the product in the cruising grounds you plan to occupy, and the quality of the box you are asking this thing to cool are all examples. And surely consider water-cooling, preferably using fresh water on a closed loop circuit from one of your FW tanks.