Fridge box construction

[GILow]

Hi all,

Curious to know what we all think is a suitable thickness for a fibreglass fridge box?

Dimensions are 1200 mm wide x 420 mm front to back x 420 mm deep. The box will be encased in two part polyurethane foam around 100 to 150 mm thick.

Layup is in epoxy and epoxy-compatible CSM. (Which, incidentally, is a bit of a pain to wet out.). All corners nicely radiused to 10 mm.

I did the first layer in a 4 oz cloth to get a good finish inside the fridge, and now I’ve added two layers oF CSM. I am debating whether to add more.

What do you think?

Matt

[coopec43]

Matt

My fridge/freezer box is a similar size to yours.

I'm using rigid polyurethane foam which I bought in 5 inch (125mm) slabs. Obviously you are using a pour in foam? If you do that a fridge mechanic (who has worked on yachts in Darwin) said a lot of problems are caused by the foam being extended out to the hull. As the sea water in the tropics can be a warm 30C (86F) the heat goes through the hull, through the foam insulation and straight into the fridge. He says you must have air circulation around the fridge/freezer.

I made a ply box and then laid up glass inside, radiused the corners and then gave it a couple of coats of epoxy paint. (Of course it is absolutely vital to keep moisture out of the foam)

I worried about frozen foodstuffs (chicken?) rolling around inside the freezer in a heavy seas and doing damage to the fragile "U" shaped condenser so I made a f/g " U" shaped inner liner with plenty of holes to allow circulation.

To adjust the amount of air circulating from the freezer to the fridge I am using a butterfly vent.

.

[Boatguy30]

I've always built the outside to use the hull or bulkheads and then the inside out of 4mm ply with a single layer of 6 oz cloth with all internal seams filleted and taped on top of that. Use a quality marine one part urethane paint or might have used 2 part this last time. Built 3 or 4 of them

[coopec43]

Originally Posted by Boatguy30

I've always built the outside to use the hull or bulkheads and then the inside out of 4mm ply with a single layer of 6 oz cloth with all internal seams filleted and taped on top of that. Use a quality marine one part urethane paint or might have used 2 part this last time. Built 3 or 4 of them

I definitely wouldn't use the hull as one side for obvious reasons.

I prefer to let air circulate around the freezer box as much as possible. For the Cold Machine I have the recommendation is that the compartment where the fridge is installed should not be less than 100 cf as it is air-cooled.

[GreenHeaven]

Originally Posted by GILow

Hi all,

Curious to know what we all think is a suitable thickness for a fibreglass fridge box?

Dimensions are 1200 mm wide x 420 mm front to back x 420 mm deep. The box will be encased in two part polyurethane foam around 100 to 150 mm thick.

Layup is in epoxy and epoxy-compatible CSM. (Which, incidentally, is a bit of a pain to wet out.). All corners nicely radiused to 10 mm.

I did the first layer in a 4 oz cloth to get a good finish inside the fridge, and now I’ve added two layers oF CSM. I am debating whether to add more.

What do you think?

Matt

Why is it important to radius corners?

[JPA Cate]

Originally Posted by GreenHeaven

Why is it important to radius corners?

Because sharp right angle corners gather "stuff", crumbs, things that drip, etc. Not only dirty, bacteria laden, but darned hard to clean. Even children's toothbrushes won't get in there, you need a pointy scraper, and that will chip the paint.

Ann, who definitely supports radiused corners.

[Boatguy30]

The blue or pink foam board with edges staggered together is for better than the 2 part pour foam.

If you are only using glass and no ply you need way more than 4 Oz over the foam more like a minimum of 24. I have used 4mm ply with 6 Oz over and then seams filleted and glassed

[GreenHeaven]

Im thinking 6mm ply glued and a layer of glass to protect and seal the ply

I only have acccess to polystyrene insulation with a lambda of 0/035 which seems to be about R5.

Its construction grade stuff with L shaped edges to slot together. my plan is 4 inches thickall around. 6 at the bottom. but its on the side of the hull and its a pain.