Building a fridge from scratch

[TQA]

As with many boats of the same age, my boat as a built in "cold box" but it is not actively chilled. Now I am getting tired of warm beer and so want to fit a compressor and convert it into a fridge.

Initial investigations suggest that there is not sufficient space around the box to fit an adequate amount of insulation even if I could get to it so I am forced to consider ripping the existing box out and building one from scratch that is a little smaller but much better insulated.

Has anyone taken this approach - and if so what materials did you use - I have been looking at some form of plastic-faced board for the inside but I don't seem to be able to find a suitable board at a reasonable price. I was hoping to be able to find plastic-faced PU insulation board, but so far google has not been able to find any. Those boards I have been able to find are either chipboard (not on a boat thank you) or expensive "shower panel" types

I had the same problem and as I was heading for the tropics and knew that I needed lots of insulation.

I used blue urathane foam 4 inches thick cut with a hot wire to shape and sanded where necessary. It is easy to work, but hot wire with plenty of ventilation and wear a mask when you sand. I then dismantled it applied epoxy resin and glasscloth to the surfaces. If you want a really good interior finish use a sheet of glass sprayed with mould release agent and laid on top. I mixed up more epoxy thickened with microballons and put it back together. I needed to add some more to fill gaps. Finished it off with some 2 pack polyurethene. After the plumbing was installed I used expanding foam to seal the hole.

If I was to do it again and had the space I might use 6 inch foam.

 

[HinewaisMan]

We too have had the joy of building a fridge from scratch for sailing in the tropics. The first (and best) step was demolishing the ratty old storage area where it was to go.

View attachment 918

Then we built a mock up using Masonite strips, newspaper and the trusty glue gun. This allowed us to see exactly how much insulation we could fit and still have a reasonable sized inside.

View attachment 919

Since we are a steel boat, we wanted to be able to lift the fridge out at times to check the steel so we built a wooden frame and a separate box to fit into it. (Getting it out will stilltake a bit of work, but it's doable)

View attachment 920

The box was built with 3mm marine ply, stitched and glassed (I knew building that Mirror all those years ago would come in useful).

View attachment 921

The box was then painted with multiple coats, ending up with lots of 2-pack

View attachment 922

before being wrapped in silverised PET film

View attachment 923

Once inserted into the frame, we lined the box with 5" of Dow Styrofoam (good high R rating and closed cell foam). The surface was then glassed, faired and painted with lots of 2-pack. The top was built separately with 3" of insulation with two top loading lids.

View attachment 925

The eutectic plate and air dam fittings were then added

View attachment 926

We used 10mm perspex to create the air dam to split the box into a fridge/freezer - cut into 3 pieces, we can adjust the size of the freezer area if we want simply by taking pieces out to leave a larger gap at the top (and we have found this works well). We fitted an Isotherm 4701 ASU system andit has been great, even though there is a 10 feet run from the compressor to the plate (add lots of insulation to the pipes).

The it was just a matter of fitting the top, buildng a few cupboards and finishing it off.


View attachment 927 View attachment 928

BEWARE! We too used the expanding PU foam from a can to fill the gaps between the insulation. Straight after doing that, I stuck my head into the fridge to drill the holes for the plate - a spark from the drill ignited the propellant trapped in the box and I found myself in the middle of a flash fire.

Having put myself out, I could see the PU foam was still burning so grabbed a handy dry powder extinguisher. Fortunately, I remembered just in time what a mess they make so used the extinguisher to "pat" the flames out.

One other thing to think about - we went with a biggish water cooled unit - it may appear to pull more power, but drags down the temp quickly. This is especially useful when the sea temp is high - we left Melbourne in Oz with water temps of under 20C - here in Turkey its over 30C and you'll find the fridge working far longer becuase the cooling water is so much hotter.

Hope this helps

P

 

[Bajansailor]

I am also planning on building a 'built in' cool box and installing a refridgerator unit on our boat - thank you for all the excellent advice and photos above! This has helped me enormously.

 

[michael_w]

I used builder's squirty foam to improve the insulation on my Contessa's fridge. Kept my beer frosty cold in Florida with the water temperature at 32C.

 

[oilyrag]

I have been thinking of trying to bond a plastic sheet directly to the celotex but I am not sure how well that would work. I don't know if say 2-3mm PVC bonded to 25 or 50 mm celotex would be sufficiently rigid or whether it would be necessary to add a further layer of plywood. I would like to hear from anyone who has done that successfully.

When converting my coolbox I lined it using white uPVC door panel - it's about 1" thick and comprises thin uPVC sheet on both sides with a foam in the middle. It's easily cut but the visible exposed edges need trimming with some flat uPVC trim. Lovely wipe-clean surface and seems to do the job nicely.

You can get it your local friendly double glazing installers and maybe, if you can get big enough off-cuts or a damaged panel (damage can be a tiny scratch), it will cost nothing.