REFRIGERATION

[sailingdog]

IIRC holding plate systems can be used for either a freezer or a refrigerator... but most commonly are used in a unit that has a section for each. I use an Engel refrigerator on my boat, and it is a dual voltage unit. If I have it set for anything more than 1.5 or 2 (out of 5) it tends to freeze the stuff at the bottom of the unit, and the top acts as a refrigerator. If I am going out on a longer trip...I will generally fill the bottom with large bottles of water, with a bit of space in them and allow the unit to freeze them solid. Then they will keep the refrigerator cold for several days with very little power use.

I would recommend beefing up the insulation in your current unit before doing anything drastic. Most stock boat refrigerators are a bit skimpy on the insulation. Also, keeping the unit fairly full is very helpful, as that gives the unit some thermal "inertia", and helps keep the temperatures stable. I have helped install mylar-faced insulation in several boat refrigerator units, and it has made a HUGE difference.

A couple of other points... One—make sure that if there is a drain to the bottom of the refrigerator or freezer, that it has a cold trap, similar to the P-trap found under a standard sink, to help keep the cold air from just flowing down the drain. Two—cover the unit with a blanket...except for the areas that need the air flow—blocking the airflow will make it overheat. Three—if it is a front opening unit, make a heavy plastic set of curtains for it, to help hold in the cold air when you open it.