After a year of contemplation, I am about to start one of my bigger
boat projects of converting my ice box into a spill over fridge and
freezer. But before I start making the purchases within the next week or so, I thought I'd post up my plan here to see what additional
advice I may receive. Then, once the plan is honed in, I'll follow up with posts on the actual
project (happening in mid-October, when I'm back at the boat).
My
Sabre 38 has its original ice box, measuring around 14 square feet. It is a bit like a tapered trapezoidal prism. A SeaFrost
engine driven holding plate system was installed in 2010 by the previous owner. It works just fine, I just hate having to turn on the
engine at least twice a day to charge the holding plate. Plus, with the
current insufficient
insulation, the SeaFrost can only manage 40 degrees.
The goal of the conversion:
Have a 1 sqft
freezer and a 3 to 4 sq ft fridge, to keep
fish rock hard, make ice, and cool veggies, left overs, dairy and
beer, all while cruising the tropics.
Some constraints:
1) The original ice box cannot be removed as it would require taking apart the entire
galley, and I'm just not doing that.
2) I looked long and hard at fitting a dorm room fridge or an Engel. Any possible location was shut down by the wife, so the ice box conversion is the only way.
3) 60 amp hours per day is the target. My
charging system (440 watts,
Honda 2000) and
battery bank (645 amp hours) were built with having a fridge/freezer installed in mind.
4) Seeing as how the SeaFrost is working, I see no need to remove it. If I'm motoring, I can flip the system on and get some "free"
cooling.
After researching (endlessly) options for ice box conversions, I have landed on installing an air cooled Danfoss 50, with an 8" by 38" evaporator plate.
Some reasons why I think this is the best option for me:
- Danfoss 50 is only a little more
money than the 35. Figure it is worth it to have the extra
power in the tropics.
- Going air cooled as there seems to be some doubts to the effectiveness of
water cooling in the
Caribbean, and I don't want the install/maintenance hassle. I plan on installing the condenser in a
cockpit locker, which should provide for enough air circulation.
- An evaporator plate over a holding plate for
budget reasons (refitting the entire boat). The plate is the largest I can reasonable fit into my 1 sqft freezer from the maker (Vitrifrigo), and is sized to have the Danfoss 50 run at the lowest
RPM.
Some bells and whistles:
- I like data. I ran across a little device called StainlessLobster, which works with the Danfoss 50 to digitally control the temperature of the freezer. It also records a host of performance metrics, so I can fine tune the performance and/or determine if there is a problem. It is pricey, but saves me from
buying the Danfoss thermostat.
- The StanlessLobster only controls the freezer, so I'll install some sort of spill over fan and probably make it digitally controlled using a
cheap thermostat from eBay.
Insulation upgrade:
- I am going to fill in much of the ice box cavity with DOW blue board. I hope to use this to create the shape of the fridge and freezer.
- I am strongly considering
buying about 30 sqft of Aerogel/Spaceloft to line the freezer. Between this, the additional blue board, and the original ice box, I should be approaching R30 in the freezer, maybe more.
- I know I need to fabricate better lids, but need to put more thought into it.
- Will use a lot of vapor barrier to stop moister and spray urethane to fill cracks and holes.
- Will line the insulation with plastic bathroom sheeting and
epoxy seams to create a stable surface for
food.
- Within the freezer, I'll create someway of keeping the evaporator plate off the walls and the
food off the plate.
- Have some sort of ducting to channel the cold air from the SeaFrost holding plate to the freezer location.