Isotherm Chiller
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There isn't much unused space in the Fulmar so choosing a seawater cooled chiller system had the benefit of not requiring air circulation or noisy cooling fans.

I mounted the compressor behind the cutlery drawer, just below the sink. You wouldn't know it was there once fitted. I carefully sited the pipework close to the transverse bulkhead so that the cupboard space could be used as before. 

Fitting the evaporator, or to be more exact autechtic evaporator (cold storage block), in the existing cool box was fairly straight forward using rubber Rawl inserts. The pipework was led just below the lid on the forward wall of the cool box. I used plastic conduit to protect the cable and insulated pipe and to prevent any spillage from the cool box top getting to the pipework. The exit to the cupboard was via a 30mm hole filled with insulating foam. 
Now for the interesting bit! The heat exchanger is a 60mm skin fitting which replaces the sink outlet, whilst still allowing the sink exit. The seawater can circulate freely around the chiller coil to reduce the temperature without causing an increase in the interior temperature of the boat. I used foam to protect, insulate and fix the pipes.
To finish off the cool box I fabricated a separator from Marley PVC-UE facia board. This is available from B&Q for about  £11.50 a sheet 415mm x 1.25M x 9mm (Product Code FB125W). It allows cool air to flow over and under it. I followed the installation & testing instructions and within 30 minutes of starting the test ice was beginning to form. The system control is sited above the cool box and the system worked well with no perceptible noise when running on economy and the engine running sensing did a perfect job of freezing.
Here is the control. It indicates when the fridge is powered up, when freezing down under full power (battery charging) and when running 'economy' (battery only). It also indicates when the battery voltage falls below a certain threshold but before full discharge has occurred.
Two weeks sailing and the cold beer voted to be a great success. No problems anchoring for more than a day and the food was kept as fresh as in any domestic fridge. Well worth the extra cost for the saltwater cooling and autectic cooler plate.