Trying to make a side dish for a quick dinner, I grabbed a frozen broccoli packet from our galley’s freezer. The problem was, it was mushy… definitely not frozen! A quick check of the other items in the freezer revealed they weren’t doing so well, either. The “frozen” green beans were also mushy, and the chicken had thawed slightly. At least our freezer thermometer read 38 degrees, so while our food had thawed and needed cooking soon it wasn’t spoiled.
Unlike many boats with a single icebox that’s subdivided into a colder section for frozen stuff, our boat has separate fridge and freezer boxes with separate top opening lids, and separate compressors. Unfortunately, the freezer on our boat has never really worked right the entire 10 years I’ve owned Priorities, our 1996 Catalina 400 Mark I.
During the summer of 2020 we lived aboard in a marina while our land home was renovated. Since much of the time we were plugged into shore power with a nice battery charger, I figured I’d try and run our freezer despite the significant power consumption I’d seen it use in previous years. It had only been running for less than a week at the slip before I found the mushy broccoli… and I actually like eating broccoli!
I probably could have hired someone to tweak the refrigerant charge on both systems, as well as replace the old mechanical thermostats. These might have helped, but I doubted it would improve efficiency by that much. There was one other issue that seemed a likely culprit as well… I suspected there was poor insulation around the refrigerated compartments, especially the freezer. During spring thaws in winter storage I would notice condensation forming on some of the lower sections of the inside of the fridge, probably meaning the insulation in that area was soaked in water. Water soaked insulation doesn’t work well at all since water transmits heat rather than insulates it. Kristin and I didn’t like the shape of the freezer, either. It was so deep we couldn’t reach the bottom easily, and I wondered if there should be more insulation on the bottom. Cutting a few exploratory holes in the fiberglass liner of the freezer and fridge boxes revealed some insulation was no longer adhering to the liner. It seemed the insulation was some sort of spray foam.
With an entire winter off from work due to the pandemic, and solo boatyard work being a good form of social distancing, I bit the bullet and figured now was the time to do a refit of both the fridge and freezer. I decided to both improve the insulation and replace the mechanicals… of course this made my winter project list get longer! And, like so many boat projects, it was quite a bit more work than I expected.
For the rest of this post, I’ll discuss the insulation improvements I made. Part II will discuss the fridge side door modifications, and Part III will discuss the mechanical upgrades.
Removing the Old Freezer Box
With no straightforward way of removing the galley countertop and no access to view the existing insulation from the side or bottom, I wasn’t really sure of what I was committing myself to. Rebuilding the freezer compartment first from the inside out seemed like the best path forward. Since the freezer never worked well anyway, I had little to lose by ripping it apart. I’d decide my path forward with the fridge after removing the freezer.
Since I wanted to replace the old mechanicals regardless, I started by removing the fridge and freezer’s old evaporator plates and related copper tubing. Then I used my oscillating tool to cut away the fiberglass freezer liner, and peeled it off the foam insulation piece by piece.
My findings? There was more insulation than I initially expected. It was definitely a “spray foam” type, mostly filling the entire space around the freezer liner.
Removal of the old spray foam was pretty miserable. Priorities is stored outside during the winter, and temperatures were in the low 20s during this phase of the project. Wearing thick, warm clothing plus respiratory protection restricted my freedom of movement. Frost built up on my safety glasses, the cabinets, and the flashlights each time I exhaled. Leaning and reaching awkwardly across and then under the countertop, I used a small crowbar and some muscle to remove only about 1 or 2 cubic inches of the stuff at each attempt, with plenty of cursing by me in between… but I got most of it out after a few hours of work.
As I toiled away, I began to wonder if removing the foam was really the right decision. There were some inconsistencies in the density, which is bad, but the foam was in better shape than I expected at first. As I got to some of the foam alongside the lower sections, however, I really struggled trying to remove it. Then I figured out why… the foam had ice in it! This made me feel a little better about all the work I had put in and had now committed myself to.
There were other observations I made about the foam, too. There was a thin fiberglass sheet that kept the foam about an inch away from the outer hull, presumably to allow the hull to flex and for condensation to flow to the bilge rather than into the foam. Insulation thickness ranged from nearly six inches at the top outboard section of the freezer, to four inches on the sides, to less than one inch under the angled bottom where the compartment was nearest the hull. From what I’ve found online, insulation for a boat freezer should preferably have an R value of 30… spray foam needs several inches to achieve this even if it’s dry. The icy one inch at the bottom and coldest corner could explain much of our efficiency problems.
The conduit for the refrigerant tubes, running through the freezer’s foam, wasn’t very nice, either. It was a hollow cardboard tube that obviously had been soaking wet for a very long time (gross!), and had no insulation at either end. The lack of insulation here probably contributed to my problems with the old freezer. Since I planned to put new compressors in a different location, I removed the conduit.
With great access to the aging diesel fuel tank vent and fuel fill hoses at this point in the project, I replaced both. Previously, when refueling, we’d smell a slight hint of diesel on the boat for a few minutes. After replacing the hoses last winter, we don’t smell diesel any more!
New Insulation
With the old freezer insulation gone, I carefully measured and developed my plan forward.
I did some research and found some good information in Don Casey’s book This Old Boat, Nigel Calder’s book Boatowner’s Mechanical and Electrical Manual, as well as several websites online. Since we anchor out a lot, having a refrigeration system that uses less electricity is definitely something we want. More insulation usually results in a more efficient system, but quickly eats up interior volume in the fridge or freezer box. I learned extruded polystyrene foam (XPS), such as the sheet foam used on basement walls of houses, can be a good insulator. It absorbs little or no water… on our home’s new addition it was installed on the exterior side of the basement wall, between the dirt and the concrete. 4 inches of foam were preferred in the fridge and 6 in the freezer… using much more eats up too much space for minimal added benefit. I used various thicknesses of Owens Corning Foamular for this project, costing $20-40 per 4×8’ sheet at a home improvement store.
Though the freezer space appeared cavernous with the old foam removed, adding six inches along all the sides sure eats up space quickly! If I used too much insulation, it should be very efficient, but I’d lose too much interior volume. I also needed to make sure the new evaporator plate and associated tubing would fit as well.
Eventually I came up with a plan for the freezer. Adding 6 inches to the bottom was easy, and brought the freezer floor high enough to be a comfortable reach below the countertop. 6 inches along the aft (stove) side fit nicely. Having a full 6 inches along the slanted outboard side wasn’t practical, though, so I put 4 inches along the bottom edge increasing to 6 near the top… still way more than before. Also, keeping the outboard side perpendicular provided a good place to install the evaporator plate later on. Much of the forward (settee) wall could be 5 inches, but I reserved some space for the refrigeration tubes and diesel tank hoses. For the side against the fridge, I only installed 1.5 inches of foam. I added an inch to the underside of the countertop as well.
Since the original insulation around the fridge wasn’t as much of a problem as I initally feared, I saved myself a bunch of work and kept most of the fridge box intact. Since the bottom foam was waterlogged, I added 4 inches of foam to the bottom of the existing fridge liner inside the fridge box. We always felt the fridge was too deep to comfortably remove items anyway, even via the fridge side door. I also added 2 inches along the tiny side by the stove to since it was heat source. Because the hot water heater was another nearby heat source, I added foam to the outside of the fridge inside the cabinet housing the water heater, too.
Installation of the new foam took some time since every piece was a custom shape, I was building the foam up in layers, and the countertop opening is pretty small. Fortunately, cutting XPS foam is pretty easy, using a long blade on a jig saw for the thick 2” pieces or a box cutter for the thinner pieces. Cutting down the large sheets was done at home in our garage, while much of the finer trimming could be made right in the galley.
XPS foam is pretty sturdy, and I made much of the pieces a tight fit, so I don’t think adhesive was very structurally important. After some experimentation, I used Loctite PL Premium 8x, also purchased from a home improvement store, as my adhesive. Many of the other adhesives for XPS foam did poorly with foam-to-foam bonds.
I tried to stagger or overlap any corners or joints with each new foam layer. Most of the joints were also sealed with Tyvek tape, available from home improvement stores. I hope this reduces water and air leakage between layers.
Though the bulk of the insulation is XPS foam, there were still small, irregular, or barely accessible areas where sheet foam wasn’t practical. For this I used an insulating spray foam called “Good Stuff,” also available at home improvement stores. After the Good Stuff cures it can be cut to shape with a serrated knife.
New Liners
To protect the foam from dents and to make a very cleanable finish, the newly insulated areas were covered with a liner made of Glasliner panels. This material is the textured, glossy fiberglass sheet you see lining the walls of some commercial kitchens. Glasliner is also purchased in 4×8’ sheets, and it flexed disconcertingly as I loaded this stuff onto my shopping cart. When adhered to the foam with epoxy in the smaller dimensions of my fridge and freezer, however, it yielded a very strong and nicely finished liner.
There are plastic trim pieces available for the corners between Glasliner panels. My initial plan was to use them throughout the entire project. I installed them on the fridge side door first for “practice” before installing them anywhere else. I did not like the results… it was too tedious and difficult to cut into attractive pieces in the space available. Instead, for the liners in the fridge and freezer I made fillets from thickened epoxy. The fillets were shaped with either a plastic spoon or the curved end of a West System mixing stick. The end result is a nicely shaped, paintable corner.
The drains in both the fridge and freezer were blocked off permanently, as I didn’t want cold air or water to leak out via the drain. This isn’t an “ice box,” and the pump connected to the drains was a pain to use anyway. Condensate from the evaporators will have to be sponged up every so often, but if the door seals are good this issue can be minimized. In case the epoxy fillets leak this condensate or any other spilled liquids, I installed some 4 mil plastic sheeting between the XPS foam and the Glasliner before epoxying in the liners. The plastic covers the bottom and is folded up the sides several inches.
After the new evaporators were installed (detailed in a later post), the hole for the new tubing conduit was plugged with spray foam as well. It’s soft enough that it can be removed in the event I need to replace the evaporators.
What I Would Have Done Different
It was hard to know what was behind the liners of the fridge and freezer before ripping stuff out. While I’m happy with the end product, I probably could have taken some shortcuts that would have gotten results that were almost as good with far less work. The freezer probably could have been improved in much the same way I ended up improving the fridge, merely by adding some XPS foam to the bottom of the freezer without removing the liner. I’d also add some to the stove side. Insulation would need to be added to the tubing conduit, too, as the old one was effectively an air duct connecting the freezer and stove area. The “forward” side of the freezer (adjoining the settee) might still need to be completely reinsulated, as this was a great time to replace the aging fuel fill and fuel tank vent hoses.
Also, based on the very low power consumption of the new system after it was completed, I may have effectively used too much insulation. Using only 3 to 5 inches of insulation rather than 4 to 6 along the outboard side of the freezer box would have increased the interior volume of the freezer quite a bit. I might have gotten away with a little less insulation on the bottom, too. I think the added space would have been enough to justify the slightly lower insulating value and presumed increase in power consumption. Most of our cruising is “up north” in the Great Lakes, though when I started this project I thought we’d be heading to the Bahamas the following winter. As a result I erred on the side of “more insulation.” Unfortunately, it was hard to know what my results would be until after everything was completed!
Coming Up
This past summer we thoroughly tested our fridge and freezer, and were very pleased with the results. We even brought ice cream with us one weekend! Despite the small freezer volume, it meets our needs pretty well and uses very little battery power compared to the old system. Much of our success can be attributed to the new insulation, and this was by far the most difficult part of the project. The work I did to the door as well as our new mechanicals helped a bunch, too. I’ll discuss the door in my next post, followed by the mechanicals after that.