Refrigeration!

Part #1 in a series

Anyone who has read this blog knows that keeping drinks cool is a big deal on BlueJ. Our hot summers, coupled with big thirst after a long race, make this an essential part of crew harmony. But what is best? For sure there is no perfect single solution for everyone, but here's our ideal.

As some know, for years we have been using a soft side cooler in the fixed icebox. This was done because adding ice to a hot icebox simply melted the ice and cooled the box down a few degrees. Maybe this would work for longer trips, but doing this 2-3 times a week was never going to work. So we carried on with the cooler.

Now I had long thought about adding a evaporator/compressor refrigeration system to BlueJ, but I had a list of questions and concerns.

• Will the plate fit in the box?
• Is there enough insulation?
• How much battery will this consume?
• Where will the compressor go?
• Will I need an AC/DC version?

I started to investigate. First I picked a vendor of choice; in this case Isotherm. Their stuff is good, and in addition they have a new technology called ISEC that greatly reduces power consumption.

 Job #1 was to pick the correct unit, and one that would fix the box.  The First 260 icebox is 50 liters, I focused on the GE80 model. Sized for up to 80l refrigerators , and the plate was 10x14 inches.

So far so good. Now the only real wild card was icebox insulation. Because I knew that Beneteau had designed the box for dealer-installed refrigeration, I was hoping that it would be OK for our hot Minnesota summers. According the Isotherm, a box this this size should have between 3 and 5 cm of foam.

When peering into the access panel from the port locker to check on the overall situation, it sure seemed like we would be OK. But time would tell!

The BIG thing that originally worried me was power consumption. I could handle the extra few pounds of weight for racing, but NOT if that included another 60+ lb of  battery. That's when a video from Isotherm caught my eye. Seems their afore-mentioned ISEC technology is designed to act like a cold plate system and greatly reduced power consumption.

OK now we are in the game. I ordered the Isotherm GE80 ISEC from my favorite online vendor and it arrived a few days later.

The install looked rather straightforward, just with a lot of steps. As long as nothing funky happened I would be done in an evening. I gathered my tools and some 10g wire and connectors.

First up was to cut the hole for the plate connectors. At 1 1/8th is is a big hole in the icebox. No going home now. Ālea iacta est.

Looking at the plug the hole created, it looks like the insulation is 4 cm, perfectly in the middle of the recommended range for this size box.

I mounted the control box outside the cooler to save space. Now test fitting the plate. Running the fragile copper tubes was the trickiest part due to the sharp turning angles. You have to be very careful not to kink them. I really don't know hard that would be to do. But finding out ruins your system.

In the port locker, mounting the compressor was rather straightforward because it came with a very nice vibration-isolating wall mount. Four SS fasteners and this was on the wall. The power and plumbing came in via small notches in the access port door, meaning that I did not have to cut the big bulkhead panel. The volume of air in the locker should be fine to keep the unit cool. It has an integral fan and is rated for good operation to 45C (115F).

All done in three hours. I loaded it up and turned it on! It happily purred and made cold air for my beer.

But the best news the efficiency. The boat has a single Group 27 battery rated at 110 amp/hour capacity. Yesterday as a test I unplugged the boat from shore power at 7AM. It was in the 80s to 90F all day. Fridge is set at 42F. Twelve hours later I came back and checked the resting battery voltage. 

That's 90% of full charge, meaning that the fridge used 8.5 amps in those 12 hours, or a 0.7A/hour run rate. Very good, and matches specs and other users observations. That's less than an incandescent anchor light! Very pleased with the install.

Part #2  here will focus on the power and 12V boat connection. And more accurate assessment of power consumption.