Notice:
The advice given on this site is based upon individual or quoted experience, yours may differ.
The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.
I have spent years thinking about the problem of refrigeration on my Catalina 25, I have read this forum for 2+ years and watched for new refrigeration ideas. Some have been worth pursuing but I never felt that I had a good solution until now. I just want to share it with the group before the season gets going. I want to say that while I have done enough testing to be encouraged, I won't know if this project will work until we get to hot weather and I have a chance to give it a good trial.
The solution I present to you is a combination of off the shelf products, technology and technique.
First I purchased a large 12-volt Igloo electronic refrigerator that is roughly 21 inches square and 17 inches deep. I removed the fridge swing door which uses 2 dimple bulges to act a door pivots and I removed the dimples by grounding them flat. This allows the fridge door to be removable like many coolers. Next I installed the fridge behind the boat stepladder by first removing the cushions and cutting in half (roughly) the wood access panel to the aft lower bilge area.
I had to cut about 1.5 inches off the fiberglass opening making it slightly larger to accommodate the Igloo fridge. To be sure that the Igloo fridge doesn't sit in any water that may get into the bilge, I purchased a large black plastic tray from Home Depot, the kind that you use to mix cement in. I trimmed a couple inches off the rim of the tray to allow it to fit cleanly into the bilge space. Then I used a couple pieces of wood and a can of "Great Stuff "foam (under a plastic sheet) to create a foam and wood wedge so that the refrigerator sits flat and is supported. To finish the job, I had the upholstery company who recovered my cushions, cut and cover a 4-inch notch out of my aft starboard cushion so that the refrigerator fits snugly in place. The refrigerator sticks up about 3 inches from the top of the cushion so most of the unit is hidden. It looks very good.
The fridge is in the centerline of the boat and the weight is as low as it can be. The best part is that the unit is mostly below the waterline and in the coolest place on the boat. This is important because the units' efficiency is directly proportional to the ambient air temperature. That is to say, that on a hot day if the refrigerator is in a cool place, it will resist gaining heat much better than in a hot place. Since the great lakes water temperature in Michigan gets only to the mid to upper 60's in the hottest summer days, the placement of the refrigerator is ideal. At least that's my theory.
Now the big problem with these electronic refrigerators is that they have no way to control the temperature or the power that they draw. They are either on full power or off, nothing in between. They draw about 5 amps per hour so in a day or 2 you will drain your batteries. You can delay that drain somewhat by recharging your batteries from your outboard motor but still these refrigerators will eat your batteries very fast
So this is where I got stuck and the plan just festered in my head for a couple years. I felt that I could regulate the temperature and the current draw if I could find a12 volt timer. I thought that I could experiment and find the ideal time to cycle the power on and off the refrigerator and thereby squeeze an extra day or more out of my batteries. But I couldn't find a proper 12 volt timer anywhere.
I have a friend that I met at work who worked for Trane, Frank is a real techo geek and one day I asked him if he had ever seen a 12 volt timer. I told him what I wanted to do, and he said he thought he could build one for me. Frank took an "off the shelf" programmable component used to control various electronic circuits and he placed it in a black box connected to a 12 volt male input and a female 12 volt output. (both are cigarette lighter type fixtures) All of this stuff he got from Radio Shack. Then the real beauty of the plan is that the programmable controller is "programmed" by attaching it to my laptop computer.
You edit the program in the computer to tell the controller how long you want power to flow to the Igloo refrigerator and how long you want power to be cut off. The program is fed into the controllers Rom memory and you are ready to go.
You plug the controller into a 12 volt cigarette lighter, and you plug the Igloo into the other end of the controller. The controller just sits and counts time until its time to turn off and then sits and counts time until time to turn on again. It draws so little power it's not worth mentioning. I have found that 40 minutes on and 20 minutes off seems to hold 30 cans of pop at between 40 and 44 degrees. That should be good enough.
So here's the plan I will start out running the refrigerator from shore power while the boat is in her slip. When we come aboard for a trip, normally we head out for 3-5 days at a time, I'll take along a block of ice and a small cooler of ice cubes because the first mate has to have ice in her drinks. I'll stay on ice for the first day or 2 until the ice shows signs of loosing the battle with the heat. I expect that the new placement of the cooler will keep my ice much better than in past years. Then I'll plug in my 12-volt timer and run on batteries.
I expect that using this plan I will have no trouble keeping things cold. Usually after 4 days out, we have to come in for fresh water, a pump out and fresh fruit, vegetables and bread. When the boat gets back to the slip, the "Guest" electronic battery chargers will top off the batteries and keep the Igloo cool until I can get back for another trip.
Sorry if this post is long, I just wanted to pass this latest project on to the forum.
Now you just have to plumb a drain system into it, add a thru-hull in a lower spot, connect the tubing to the thru-hull so you can drain the melted ice, then . . .and . . .<img src=icon_smile_wink.gif border=0 align=middle>.
After the heat wave hits, post an update on how cold the beer stays and how long the batteries last.
Notice: The advice given on this site is based upon individual or quoted experience, yours may differ. The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.