building a refrigerator box for a boat

Building our Refrigerator Box: Stage 2

Wednesday October 7, 2015

building refrigerator box

The last I had left you with stage one progress on our refrigeration box is that we’d measured and cut all the pieces of marine plywood, nailed them into place, and then filled the cracks with colloidal silica.  Doesn’t sound like too much work but did take us the better part of a few days.  Things still felt like they were flying along though since having large items constructed and taking up space in your galley is a constant reminder you’ve finished something.

The next step after the box itself was set up and water tight was to insulate it.  Instead of using the same spray foam we’ve been lining our hull with, or the same kind of stuff we spent hours chipping out of the old fridge, we used polyisocyanurate foam.  Which is a fancy way of saying that we bought the big sheets of foam insulation from Home Depot.  Overall we’re looking for a depth of 3″ of foam insulating our refrigerator.  This made it an easy choice to get the 3/4″ sheets instead of 1/2″, ensuring we’d only have to do 4 layers vs 6.  Less work for the same job = much better in my book.

Once the huge 4×8 sheets were dragged back to the boat we needed to cut them to size to fit in the box we’d just built.  After Matt had done a little research on the subject he’d found out that staggering the joints is the best way.  This means that instead of cutting 4 sheets of insulation the same exact size for the bottom and then measuring for one side, cutting 4 sheets the exact size, and moving to the next; you do one full layer around before starting the next.  So each layer for the bottom should be 3/4″ smaller on each side than the previous one.

Although it sounds like this should be one of the easiest steps in the process it was actually one of the hardest and most time consuming.  For each layer and each side in that layer we needed to take measurements (with two sides being odd shaped pentagons), mark and trace those measurements onto a sheet of the insulation, try and cut as straight of a line as possible with the knife on our Leatherman, and then squeeze it into it’s new spot in the box.  Usually with a few adjustments to be made.  Sometimes with the whole thing needing to be redone if we didn’t get the angle of the pentagon right.  It was a pain in the butt.

When we had 3″ of insulation all the way around we had to begin to shape the freezer as it’s own separate part of the box. Cutting two sheets to make a divider, we then built up the freezer space from the bottom and sides to make it smaller but with double the insulation.  In the end the space was bigger than we thought, bigger than we had in Serendipity, and something we should easily be able to fit a half gallon of ice cream in. With the help of the best hand tools for sale, we were able to do our work faster and with far lesser problems than expected.

After that we ran foil tape around all the edges to seal off all the porous foam and making sure no water could get inside.  Another pain in the butt project but mostly just because it was so time consuming.  At one point we decided to save it for an after dinner activity where we worked on this tedious task while sipping Miller High Life and watching Archer on Matt’s tablet.

The next day was the fun step of putting all of the 24 pieces in to make sure they fit.  Which they did!  Bad part though was we forgot that we were supposed to stop 3″ from the top to make allowances for the lid.  Ooops!  Luckily the Dremel was on hand and ready for the project.

To permanently attach the sheets together we used two methods.  The very first layer which was being attached to the epoxied wood was stuck in place with a thick batch of colloidal silica.  We clamped the insulation to the wood, placed other long sheets of foam inside as a bracing system that would push the two together from the inside and left it overnight to dry.  The next day we finished adding the remaining layers with a gap filling insulation foam.  Once again it was left overnight to dry and the next day we filled all the remaining cracks with another thick layer of colloidal silica.

clamping sheet insulation for fridge box

clamps holding foam in

Whew.  I’m tired just reliving those steps.  But we’re not done yet for stage 2!

Since we couldn’t just paint the inside layer of sheet foam and call it good (although by this time I wish we could have) we needed a solid surface in there.  We decided to use fiberglass bathroom paneling. Turning it around we made sure the bubbly side was facing the insulation and the smooth side was out.  This was attached with colloidal silica and also had all the seams filled with a thick layer.  Another overnight of drying and then everything was ready to sand down and be given a coat of primer.

fiberglassed inside of fridge

building a refrigerator box for a boat

inside of our fridge box

Seriously, I’m getting exhausted here reliving all these steps.  And to think we’re still near nowhere near being done!  Those of you who have written stating that you’re about to start your own project like this are lucky you told me or I probably would end the post here, just attached a few more photos and call it good.  Sheesh.  If we were smart we would have purchased multiple dorm fridges instead and added more solar to cover the charge.  I’m sure it would have been cheaper and much less heartache in the end.

Buuuut, we’re stubborn.  And so are you people that want to do this yourself.  Don’t say I didn’t warn you.

Ok, onto the lid.  This also required four layers of sheet insulation to equal the 3″ total we need for the top layer of insulation.  The *easiest* way to do this would have been just a simple rectangle to open and close over the areas, but it would not have made it very easy to open and shut in the end.  We needed three of the four sides to be at an angle. So, a little extra work now will save us a lot of hassle in the future.  We had been so proud of ourselves when we whipped together the lid for the fridge area in just a matter of a few hours, all measured, glued, and angles cut.  Only to find we cut the angle the opposite direction we were supposed to.

Another oops.  And other trip in to Home Depot to get an extra sheet of insulation so we could try again. One attempt later and we had it right.  From there it was set aside so Matt could begin multiple layers of fiberglass on it.

The very last step in this stage two of building our refrigerator box was to create the holes that will allow the cold air to flow from the freezer where the evaporator will sit and into the fridge.  In theory, once we have everything hooked up there will be a thermostat in the fridge area that reads the temperature.  Once it gets above a certain point a fan will kick on in the freezer and begin flowing cold air from the freezer to the fridge via the tube in the bottom.  Any warm air will circulate from the tube in the top of the fridge back into the freezer to be cooled down once again.

We also placed two shims inside the freezer for the evaporator to attach to which will then keep a 1/2″ distance between it and the wall of the freezer.

hoses leading from freezer to fridge

There you have all the work that went into stage 2.  Really, really should have bought those dorm fridges instead.  Stay tuned for stage 3 where we hopefully get this up and running!

getting right angles

Building our Refrigerator Box: Stage 1

Sunday September 27, 2015

Matt leveling floor

After searching for what seems like months now for the perfect refrigerator for Daze Off, we have come to one conclusion.  Although it would be soooo nice and sooo easy to buy a pre-made one that we just slide into place and plug in, there seems to be two definite problems with that.  1.  Our hull curves in so much that any of the larger sized fridges could not fit into the space we’re looking for, and if we put it against the flat surface in the center of the boat then the depth came out much further than one would like to have remaining foot space in their galley.  And 2.  The ones that would fit either of those areas were too small for our taste.

To go into a little further detail, we would have preferred a pre-fab fridge with drawers, but those all fell in the category of not fitting into the space well.  All the front open fridges we could find that did work with our hull shape and also the layout we have in mind for our galley usually fell in the 4 cu ft range.  We had 9 on Serendipity.  That would be cutting our cold food storage in half.  Not that we always filled Serendipity’s fridge to the top (unless we were headed out on passage or to the Bahamas), but it became a terrible game of ‘I need what’s sitting under 8 other layers’ the times we did.  Plus we could only imagine opening the door only to have all of the items inside topple out on us if there were any kind of motion on the ocean.

The only good solution left was to build our own.

A lot of planning went in to this (on Matt’s part, god I love him for figuring all of this out), and once we had our approximate measurements of the outside of the box it was time to head to the hardware store to buy a sheet of 1/2″ exterior plywood to begin the project.

Our first step was making cleats to add on to a few of the aluminum frames that came out on angles from the hull, allowing us to be able to have a level board sit down when we were finished.  Once the cleats were installed we were ready to cut the bottom board but also had to take into account the frame, slicing a small section out of the plywood’s edge so we could fit the board around it.

The back wall of the box needed to be built in two pieces to allow for the curve of the hull.  We do want to maximize the usable space in this fridge as much as possible which is why we decided not to build it straight up and leave a large gap between the box and the hull. Making sure that everything was level and that we’d be ending at 90° angles, we measured and cut the back two pieces, also having to make an allowance for the frame on the bottom of the two.

I had thought the sides would be much easier to cut but forgot to factor in that they needed to be pentagons to, once again, work with the curve of the hull.  You should have seen the drawings I had in my notebook as Matt was giving me measurements to write down. Top – 23″; front side 19″, top back side – 8″, remaining – 12″.  Eventually I had to make drawings to keep it all straight so we could remember what line connected to what when it was time to mark the lines on our plywood.

The front was by far the easiest, and once we loosely assembled it together it was nice to step back and say “Wow, look at all we were able to complete in one day”.  Except, we were still so far from finishing. I had also forgotten that we needed to cover the metal frame that was running through our refrigerator box. Using sheets of Eurolite for this we cut two pieces that covered the top and side and also cut some sheet foam to slide under that area so that once it was closed off it wouldn’t be sucking cold air into a useless area.

That was enough to fill one whole day, but in the end it still felt like we accomplished a lot more than we have on a normal day lately.  Day two was prepping the wood for final installation and also do all the final prep to that space before the boards were permanently placed, such as insulating and running conduit.

While I was sent outside to ‘epoxy the s#*t’ out of the boards, as Matt put it, he was inside working on more spray foam insulation. It turns out the previous owners of our boat once again had it all wrong.  Where you’re supposed to have insulation from the overhead leading to the waterline, they instead had bare metal all the way down to the waterline and then decided to insulate from there to the bilge.  Oh that’s right.  They needed a place to hide their drugs.

So Matt went through and properly insulated the rest of the hull and made a huge mess in the process when he tried to add a little extra to the existing insulation to the overhead.  But it was also kind of nice knowing that I’m not the only one who makes big mistakes on this project of a boat.  So yeah, a lot of my free time is now going to be spent scraping off bubbles of foam from the walls, cabinets, floors, and even the plexi hatch.

A few days later once the plywood had two coats of epoxy we were ready to screw all the boards in place and fill any gaps.  Working with my new best friend, epoxy, we added some colliodal silica to make a nice thick paste which we then ran along all the cracks and made sure they were thoroughly filled.  This should make sure the frame of the box will be completely water tight.  A very good thing when condensation is a high probability.

So there you have it for stage one of building our own refrigerator box.  Stay tuned for the next step where we get to insulate!

Matt making board level

Matt measuring board

getting right angles

layout of fridge box

spray foam insulation in galley

fridge box

inside of fridge box