Cool runnings

I have a long and acrimonious history with boat refrigeration. Like a lot of cruising folk, I’ve been tied up in some godforsaken long-drops of ports waiting for fridge parts to arrive from elsewhere – or the people to install them to turn up in the few hours between siesta and sundown.

A defunct fridge caused us to cancel a lucrative 10-day charter in the Caribbean years ago – and left us with tepid Heinekens after a hard day’s racing at Antigua Race Week.

True, I do suffer from that sailor’s complaint MPS – Mechanical Paranoia Syndrome. We should form an association and hold meetings: “Hi, my name is John and I’m a mechanical paranoid.”

We’re the people who change the engine oil 100 hours before it’s due and pull the water pump off because it doesn’t seem to pump as much water as it used to.

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We are wary of having anything aboard that we can’t fix ourselves or that needs special tools – like fridges.

I solved the fridge problem with my own boat by not having one. Most of our sailing was offshore at that stage and we’d bulk-buy meat, sterilise it in a huge pressure cooker and pack it in sterile Agee jars.

Some fruit and veges last long enough for an average passage – cabbage for example, and much of our time was spent in high latitudes where the water was cold enough to refrigerate some foodstuffs in the bilges. Bananas were bought green – or we gorged on fruit while it was fresh and available.

There were occasional treats: New Zealand tinned butter which is, oddly enough, common in the Pacific Islands but hard to obtain in its country of origin and the Danish tinned ham and some canned bacon which provided us with breakfast for days.

That worked well for years, until we came across a public health specialist who painted a gruesome picture about the dangers of a lingering death from salmonella or food poisoning from the tiny little microbe that might manage to slip past the rubber seal on an Agee jar.

Then I bought a boat which came equipped with an engine-driven fridge system. The installation probably dated back to when she was built in 1985 and came with nicely-crafted, stainless steel fridge-freezer boxes and a compressor and two-belt drive system that looked reassuringly agricultural.

“Oh yeah,” a friend said, “that’s a compressor from a Kenworth truck air conditioner.”

The MPS in me said that running an engine for an hour a day not under load wouldn’t do it any good – or the atmosphere it was pumping its exhaust gas into. And I recalled the commercial fishing boat that developed a leak in a crankshaft seal because of the athwartships pull exerted by its fridge compressor.

No matter, our own unit worked – for a year. But then it developed an ague. It took longer and longer engine running time to bring it down to temperature and tell-tale bubbles began gambolling through the sight glass.

This became a recurring theme. To abbreviate a long story, the system had to be re-gassed four times in five years – at about $700 a pop. “Must be leaking out the pressure relief valve,” the final fridge man said, “buggered if I can find it though.” I thought about investing in the gear to do it myself – but baulked at lugging a load of refrigerant bottles, gauges and parts.

The recalcitrant chiller in the condenser rusted through at one stage and leaked coolant into the engine salt water coolant circuit. There must be nothing else in the world that can annihilate a cooling water pump impeller as quickly – and thoroughly – as engine coolant. When I pulled the cover off to look just a few vanes remained on the impeller and the rest were a gooey mess.

Meanwhile, I’d been eyeing magazine adverts for eutectic fridges – install-it-yourself Isotherm units – and canvassing people who had them. The replies were, to a person, enthusiastic. The Isotherms were quiet, efficient – though people stressed the need to have ample means of power generation to sustain the extra battery drain.

They came in air-cooled or liquid-cooled models – though I favoured the former because it meant not making any more holes in the boat.

Our boat has two 75-watt panels and a Rutland wind generator which trickle-charges into the batteries 24/7.

The decision was made when, at the last re-gassing session, I asked the technician what he thought of the eutectic setups. He wasn’t keen – but then, I guess he was looking at the possibility of a good deal of his income stream drying up.

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The decision was made.

First, I removed the old unit. The compressor mounting plate was part of an engine mount and I did consider lifting the engine to gain access – but 10 hours squished in the galley on hands and knees, leaking blood from battered knuckles, did the trick.

The condenser, associated plumbing and wiring with other bits and pieces took another day to dismantle – we almost had a farewell party as we ditched the 25kg or so of assorted hardware ashore.

One thrill came as I drilled through the freezer box to run pipes for the Isotherm holding plate. As the drill bit broke through the thin stainless steel plate, a 30cm geyser of methylated spirits spouted from the hole – nothing about that on the safety plan. When it had subsided, I pumped the space between the two stainless liners out and removed 30 litres of the highly flammable purple spirits.

The Isotherm unit – from Auckland’s Fridgetech – arrived in two boxes; the holding plate in one and another holding the compressor and miscellaneous installation equipment. The compressor looked like the unit that you see when you’ve brushed the dust, cobwebs and dead cockroaches off the back of your household fridge. That’s easy to understand – a similar setup to the one that purrs contentedly away for decades in your household – but driven by 12- or 24-volt batteries instead of 230V mains power.

The plates can be bent to accommodate the size and/or shape of the fridge – which in my instance was a U shape. The compressor comes with a nifty stainless bracket – I fastened the bracket under the cockpit and clicked the compressor into the spring-loaded retainers.

I needed slightly longer copper pipe from compressor to holding plate – which was quickly supplied by the Fridgetech crew. The pipes have fittings at each end so they can be connected without spilling any refrigerant.

With all the hardware in place – about a day’s work – I wired the unit in, flicked the switch and waited for the reassuring hum that would mean the beer was getting cold. No joy.

I tried all the troubleshooting solutions in the comprehensive handbook and a few more suggested by Greg at Fridgetech. I crawled under the cockpit with a multimeter in hand – the polarity was right and the meter claimed that 13.2 volts were flowing into the system. But still no go – and the beer was still at blood temperature which, in my case, was getting pretty hot by then.

Greg sent a new electronic control unit which I installed – but still no cooling took place. “That’s normally the only problem we have with these Isotherms,” he said.

I recalled the previous fridge man’s disparaging smirk when I mentioned going to an electric installation – and re-read the installation guide book.

Finally, Fridgetech technician, Sean Ervine, turned up and crawled under the cockpit. Soon, from the depths of the gloomy space I heard: “You’ve only got 10.6 volts at the compressor.”

He slid out, checked over my wiring and showed me how to remedy it – and left. Somewhat red-faced, I followed his instructions and sure enough, half an hour later, the Isotherm sprang to life. In an hour or so frost had formed on the holding plate and, by evening, the beer bottles had beads of condensation rolling down their cold, green glass sides.

The batteries are holding well. The freezer’s full – and I haven’t had to run the engine without any load for ages. At last, a fridge I can live with.