Refrigeration is Very Nice - but....
Refrigeration is very nice but it can get involved and expensive. [realize I live in the Pacific Northwest so my situation is different than yours - adjust accordingly]1. How cold do you need it? Hard ice cream, soft ice cream, or melted ice cream? Our Adler-Barbour "Cold Machine" will provide "hard-soft" to soft ice cream depending on the type of ice cream and then for only two days max. After that it's soft to very soft. Put a cover over the freezer part to keep the cold in.On the other hand, it makes ice great! Margaritas are great on hot days, maybe even better than ice cream.2. Electrical conductors: Due to the power draw and startup power needs the conductors from the battery to the main panel and thence to the compressor need to be fairly heavy and marine grade wire is expensive. If it will shorten the run considerably consider installing a sub panel.3. Battery capacity: I went from two group 24s to four golf carts and a group 27 (for starting - when it needs replacing it will be smaller). The golf carts give me almost two days on the hook.4. Charging: Get a high-output alternator and multi-step regulator. I have a Balmar 70A alternator and a Balmar three-step alternator which works absolutely excellent. The 70A alternator only needs one V-belt whereas with a larger one more belts may be required. If you are constantly on the move then maybe an engine driven unit would be better than 12V. 5. Battery conductors: With the larger alternator and batteries figure on #00 conductors (read "expensive") with, say, #2 conductors to the alternator and engine ground. The new batteries also need acid proof boxes to make the installation NFPA code correct if the batteries are liquid acid type which is probably the cheapest way to go.6. Additional charging: Recommend a couple large solar panels, say Simens M75 or equal. This will really reduce engine running time. Running the engine to charge batteries is hard on the engine (carbons it up) and it is noisy. 7. Additional insulation: Check the insulation around the ice box and chances are it could use more. The easy part is buying closed cell foam spray insulation but the hard part is applying it. Also, since it continues to expand for several days it can be hard on the cabinetry if over applied.8. Inverter: A great thing to have when going to the dock especially if it has multistep charging capability. It can charge the deeply discharged batteries properly as well as supply AC power for those other devices. For comparison purposes we have a Freedom 10 which works fine and can pump 50 amps into discharged batteries.8. Cost: The cost for the A-B unit is the cheap part; it's all this other stuff that adds up - that's the domino effect.Oh, and did I mention an additional heavy-duty battery selector switch, large fuses and breakers? Oh well, what's a few hundred more bucks??Would I do it over again? Pass me a Margarita and I'll say yes. No more disruptive trips after ice and carrying it down to the boat. Ice blocks don't work all that well anyway.If you can afford a boat you can afford refrigeration. It's only money. The above is my setup but other combinations (holding plates, engine driven, gel batteries, etc.) will alter the situation accordingly.