For energy efficiency, you want to keep the condenser temperature as low as possible. The higher the temperature at the condenser, the higher the pressure is that the compressor
needs to pump up against, the lower the efficiency of the system. It has to do with compression
ratios. The lower the fridge temperature the lower the pressure is that the compressor has to "suck", so if there is a big difference between suction and discharge pressure, the amount of gas the compressor can move for each stroke goes down. In industrial systems they try to keep the ratio below around 1:8. If you know what refrigerant you have, you can look up the temperatures and correlated pressures to give you an idea of where you are. Or else post here, and I can do it for you
You need to go the other way, use a salt water
cooled condenser if sailing in warmer climates especially.