REFRIGERATION: When we bought our boat it had the usual double skinned frig/freezer compartment, but no longer any means of cooling it. We fitted an electric unit form Fridgetec in Albany, the second smallest size. Access for the piping from the unit installed in the cockpit locker to the cold cabinet was difficult, especially if we were to preserve the fluid between the two skins of the cabinet.
In the end we drained the coolant (antifreeze) and drilled through both stainless layers.
As stainless steel is a poor conductor of heat, and there is about 3cm of airspace between the layers ,we were not overly concerned.
The result is as hoped. In summer the unit runs for less than 10% of the time, our food is cold, and the house battery -104ah from AA Solar in Silverdale - is still well up in the morning.
Turning down the thermostat freezes the bottom of the cabinet, which has a capacity of around 70 litres.
Total cost including an hour of professional help and advice - $1200.
Since then I have bought a 100w flexible solar panel and an MPPT controller (up to 30%more efficient than older regulators). The panel, 3mm thick, will go on top of the canvas dodger as I have not finished the bimini, which will frequently be furled anyway. ( Colin Moore, Raven 31, Mimic )