[C38] Icebox Insulation

[Tom T.]

Hi Steve,

In regards to your question on insulating the ice box using spray foam or foam board, I have done both spray foam and the hard foam board type upgrades and both have merit.

You may want to use both types of insulation since it is impossible to get to the forward side of the box and very hard to get to the outboard port side of the box.

In the sail locker, I made a round hole for a round access port.  I think it may be about 9" but access will be slightly larger if you don't install the ring until the project is finished.  I used 1" foil backed foam board cut in 6" wide strips and glued one after another with foam adhesive administered from a caulk gun.  I used metal A/C tape to hold each board strip in place until the glue had set.  Each strip was carefully cut to make a good fit.

On the outer port hull side of the box, I insulated with small plastic sandwich bags filled with pieces of fiberglass bat.  This is crude but I didn't want to make that side permanent in case I ever had to remove the ice box liner.  Spray foam is almost impossible to remove if the box ever has to come out.  Spray foam is a very good construction material.  On our Catalina 27, I foamed between the v-berth and hull to make the hull rigid.  You can now hit your fist against the hull and it feels like you are hitting a concrete wall.  I drilled small holes which would be hidden by the v-berth mattress and shot the foam into the holes using a predetermined 5 seconds per hole which gave me the coverage I desired.  You will have to experiment with foam to get the right size after it expands.

It is much better to shoot foam in many small shots from multiple entry points instead of trying to fill a large area all at once because as it expands, it can develop great expansion forces making things warp or break, not to mention a denser and less efficient R value of the resulting foam.  Great Stuff is my favorite but it does expand greatly and with great force.  The newer brands of spray foam that use latex and don't expand as greatly and are cleaner to use and clean up but they also don't have the R value of the Great Stuff types.

I insulated my ice box in 1995 and those little "temporary" plastic sandwich bags I filled with fiberglass mat are still in place, none has leaked, and all are still working well.  I also used them below the ice box because I wanted to be able to fish hoses and wires under the ice box if needed.  If I had foamed under the ice box, I would have first put in a piece of PVC pipe as a conduit.  I'm sure the foam would fill every crevice better but as I mentioned, foam is forever.

Properly done, fiberglass bat has a similar R value to the urethane foam board.  Don't use Styrofoam because it doesn't have as good of an R value, it burns easily, and it melts from contact with many chemicals.

There is about 4 or so inches between the forward bulkhead of the sail locker and the aft side of the ice box liner but if you use strip foam board there, you will have to leave some room for your hand.  Insulate the outboard hull side first or you will never be able to get your hand there once you insulate the aft side of the box.

When I replaced my fresh water tank some years ago, I wrapped the new water tank in plastic sheet and then used spray foam under the new tank so it would be supported. The old tank cracked from heavy pounding in rough seas because the tank was flat and the hull rounded leaving the middle of the tank unsupported.  By wrapping the new tank in plastic sheet, I can now easily remove my water tank if I ever want to.

If you could figure out how to remove the ice box from the boat, you could wrap it with sheet like I did and foam it in place but getting the ice box out will be a trick.

After insulating the ice box as well as I could with the foam board and bags technique, I then made pieces of foam to line the inside of the box with a snug fit using 2" Styrofoam.  This reduced the size of the inside of the icebox making it easier to cool as well as giving great insulation.  My refrigerator conversion uses the components from a small 120v refrigerator and the evaporator is in the outboard side of the icebox.  After inserting it in place, I slid foam board pieces cut to shape the evaporator and ice box liner for additional insulation.  I can remove the pieces in the ice box by just lifting them out.  They are press fit in place.

The last thing I did was glue pieces of 2" Styrofoam to the bottom of the wood ice box top lids and sanding the foam with a sanding block so they would fit easily with very little clearance.  I then painted them with several coats of epoxy resin to toughen them up.  Leave enough clearance for the epoxy coating.

I'm sure you can do a neater or better job than I did but as far as efficiency, I can' complain on the results of my project.  Even on a very hot day under sail and running the refrigerator on battery/converter, the compressor cycles and uses very little battery.

My two biggest energy hogs were my Autohelm and my refrigerator.  I fixed the refrigerator problem with insulation and I fixed the Autohelm problem by assisting the steering wheel with bungee cords when underway so the Autohelm only has to make small adjustments with no weather helm imposed on it.

I can now sail in hot weather for several days without cranking my engine because now my two solar panels will keep up with my energy needs.

Good luck,
Tom Troncalli
"Renata" hull #95
St. Pete, Fla


----- Original Message ----- 
From: Steve Smolinske 
To: Catalina 38 Listserve
Sent: 12/1/2009 11:12:41 PM 
Subject: [C38] Icebox Insulation


Tom, and Max

This question is following up an earlier post of yours describing how you insulated your ice boxes.  I have my galley torn apart to replace the laminate tops and finish the cabinets  I was hoping with the counter tops off I would have access to area between the icebox and the liner, no such luck.   You mentioned you cut a hole in the aft bulkhead and slipped insulation strips in, how much space is there between the liner and the ice box?  Catalina suggested drilling holes from inside the box and spraying in foam, Im not crazy about that as you can not gauge or measure the coverage your achieving.  

Max, how did your project go?

Steve
Peregrine #312
Seattle
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