Now that you've installed an efficient stove, maximized the use of storage and counter space, and figured out where you're going to keep the garbage, you have one basic question left about your galley: how are you going to keep food cold?
At home, the answer is simple: you simply buy a big refrigerator, plug it in, and let her rip. Things aren't quite that simple on a boat.
For generations, those venturing forth on the water have fought the battle of fresh food. Long ago, sailors died for lack of fresh food. The modem sailor is more likely to kill for a cold drink or a crisp salad. I sti1I treasure the memory of pulling a frozen block of lasagna out of the freezer after a week at sea, and a couple of hours later having a meal that could have just been cooked at home with fresh ingredients. By such memories are cruisers created.
But the cost of that type of food can be high, in dollars of initial investment, in gallons of diesel fuel to charge batteries or run compressors, in the time and hassle of installing systems. Do you want refrigeration? Do you need it?
But before you decide whether to improve your existing icebox, build a new one, or rip it out and install a ready-made portable, you should think about how you use your boat, what you really need in the way of keeping things cool, and how much you want to spend.
The fact is that relatively few boats of any size come with truly good chill boxes. A chill box is one of the most expensive installations on any boat, being intensive in both labor and materials, and taking up a lot of space. People expect iceboxes to perform, and builders happily oblige them.
The traditional icebox, with its cork insulation and stainless steel liner, was a joke. It could eat literally hundreds of pounds of ice a week, and still manage to spoil half the food. We once had a poorly insulated icebox of about four cubic feet which managed to consume 25 pounds of ice a day in the temperate climate of New England without batting an eye, and it could probably have doubled that appetite in the tropics. With that type of installation, you might as well learn to live off canned goods.
But you don't have to live that way in the age of efficient foam insulation and properly designed boxes. You can even have refrigeration if you want it, but before you spend your money, let's look at the options.
Ice
The first option is, basically, to do nothing at all. Use ice. How practical this is depends on how easy ice is to come by, and how long it will keep in your box. In almost any harbor with an active commercial fishing fleet, there will be an icehouse close to or on the harbor, and it may only require a short dinghy ride to get a big block of ice at a reasonable price. In our home town of Newport, for example, the icehouse is a stone's throw from the harbor. In the 10 years or so we've been here, a 25 pound block of ice from the vending machine at the ice house has gone from $0.75 to $1.25 - a big jump in relative price, but still a bargain when it comes down to it. If that block of ice lasts two days, and you live on your boat for 100 days a year, you'll have lugged 1250 pounds of ice and spent $62.50, plus a fair number of hours rowing or walking to the icehouse.
At that rate, you could afford to haul ice for about a decade instead of buying a typical icebox conversion setup.
But that's an oversimplification, too. In places where ice is less accessible or is more expensive, you could spend a lot more time and money ferreting out what they can't give away in Antarctica.
Since ice making is usually a local monopoly, you may be at the mercy of the local industrial Structure. Instead of 5c per pound, you might pay ten times that amount. We've done it.
Ice has the advantage of cooling a box quickly. You can also chip it to use in cold drinks. It makes no demands on your engine, your batteries, or your pocketbook. But it can turn into a pool of stinking water in the bilge, if there is no sump, or it can spoil food in the bottom of the icebox, if there is no proper drain.
Ice is also inefficient It cools by absorbing heat during its transformation from a 32" solid to a 32 degree liquid. You're then left with a volume of cold water which will cool things to some degree, but is vastly less efficient than ice itself at the job.
But if you use your boat only on weekends, and are prepared to bring both ice and perishables to the boat weekly, it will do the job at minimum cost.
Engine-Driven Systems
The traditional alternative to ice on larger boats is the holding plate system utilizing a compressor driven off the main engine. Holding plates are merely tanks of liquid that freeze at temperatures lower than the freezing point of water. A compressed refrigerant passing through tubes in the holding plate absorbs huge amounts of heat from the liquid in the plate, converting it to a low-temperature ice. As that ice melts, it absorbs heat from the box, cooling the contents. Since the liquid solution is contained in the holding plate, there's no mess in the icebox.
Since the solution in the holding plates melts at a temperature lower than 32 degrees it can keep the interior of the box at lower temperatures than are possible with ice. With the proper solution inside, holding plates can be used to chill a freezer.
There are drawbacks to holding plate systems. They are expensive. A basic system, consisting of holding plate, compressor, condenser, and peripheral hardware, will cost anywhere from $1500 on up. Installation, assuming you have a good icebox, can double the basic price. You probably won't get more than half your investment back when you sell the boat.
Mounting the compressor on your engine can be a problem, requiring modification to engine boxes, pulleys, belts, plumbing, wiring, etc. Installation of a holding plate system is within the capabilities of a boat owner who's handy and patient, but it is not the job for a rank beginner. Installation of a holding plate system-and making it work properly-is probably on a par in degree of difficulty with replacing a gasoline inboard with a diesel.
Another drawback of the engine-driven holding plate system is its cyclical function. With a good system, it may be necessary to run the engine about an hour a day to freeze the holding plate. Over the next 24 hours, the plate slowly thaws, absorbing heat from the box and keeping things cool. Then you must run the compressor again to repeat the cycle.
Even the best systems require daily operation to keep box contents cool. This may be fine if you're out cruising and are running the engine either for propulsion or for battery charging, but it does nothing for you if you're at the office all week with your boat in the marina or on the mooring. You'll still have to remove perishables any time the engine can't be run on almost a daily basis.
One way around this is the addition of another compressor driven by 110 volt shore power or the ship's 12 volt power supply. If you're plugged in dockside, a 110 volt compressor can keep the box functioning all week without attention. Likewise, if you're plugged in and have a battery charger, a 12 volt compressor can do the job while you're away.
For this option, you can add about $1000 to your basic engine-driven holding plate system.
Holding plate systems are therefore best suited for larger boats (due to cost) which are lived aboard or cruised for ex- tended periods. For this type of use, the holding plate system is probably unsurpassed, although you're still pretty much tied to the boat when in port if there are perishables aboard. If you're away longer than overnight, you have a box of spoiled food.
Hermetically-Sealed Compressor Units
Somewhere between the icebox and the engine-driven system in cost, complexity, and efficiency, lies the system most familiar to us, because it uses the same technology as your home refrigerator. It is the hermetically-sealed, electrically powered, thermostatically-controlled compressor/evaporator system.
In your icebox, you install a unit that looks just like the small freezer compartment of an old fashioned refrigerator. The freezer compartment has room for a few ice trays, but that's about it. The compressor, most often air cooled like the one in the bottom of your refrigerator, can be located almost anywhere in the boat that has a flow of cooling air.
Installation is simple, involving bolting the evaporator in the box, and joining it to the compressor with copper refrigeration tubing. You then have to get power to the compressor, usually a simple matter of running a couple of wires from the electrical panel. Barring unforeseen difficulties, you can install this type of system in a weekend.
There are several advantages. Sealed compressor systems are cheap, easy to install, and readily available through mail order discount stores. The Adler-Barbour Coldmachine, long a popular system of this type, retails for about $800 to $1000 and up, and is commonly discounted by 40% or so.
Other systems of this type, such as the Frigomatic and Norcolder, are slightly cheaper.
Since it is thermostatically controlled, the sealed compressor system can maintain a constant temperature in the icebox. Its cycling is not affected by when you run your engine, as in the holding plate system. You can plug the boat into the dock when you go to work on Monday and have reasonable expectations that the food that was cold Monday morning will still be cold Friday afternoon when you're ready to go again.
There's also one very large disadvantage. The sealed compressor system is power hungry, and if you lack access to shore power or huge banks of batteries, you could be in trouble.
A sealed compressor system will typically draw from 4.5 to 7.5 amps when running, depending on the size of the system. Have you ever noticed how many hours a day the refrigerator runs at home? Eighteen hours? Twenty hours? With a poorly insulated and sealed box, that hungry little unit could run the same amount of time on your boat. Eighteen hours at 7.5 amps is 135 amp hours per day. It will take two more large automotive type batteries on your boat to provide that type of 12 volt power source when the boat isn't plugged into the dock.
On a power boat, this isn't a problem. If the boat isn't plugged in dockside, the engines will be running for a reasonable period of time any day you're going someplace, so the power consumption won't be noticed. On a sailboat, the story is different.
If you have the typical 50 amp alternator with an automatic voltage regulator, an hour of engine running might at best pump 25 amps into your batteries. At that rate, it would take over five hours of engine running to replace the 135 amps drawn by the refrigeration system. Even replacing the automatic regulator with a manual one will require three hours of engine time.
So start out by adding a 75 amp or larger alternator, plus a manual voltage regulator. To that, even for a smaller sea ed compressor system drawing only 4.5 amps, add another 105 amp hour battery to whatever you already have on board, at an absolute minimum. You've just added $400 to the basic cost of your system.
If you're plugged in dockside and never go anyplace, you can get by with a big battery charger. But if you unplug for more than a weekend at a time, the other additions to your electrical system are a must.
You can, by rebuilding or replacing your existing icebox, greatly reduce the number of hours the system will have to run. But it's still a power-hungry approach to refrigeration, one best suited to dockside living and powerboats.
You can also increase efficiency with a water-cooled condenser, rather than the normal air-cooled one. These are only available as options with some of the systems, such as the Adler-Barber Super Cold machine, but that, too will add $150 or more to the cost of your refrigeration project. A water-cooled system also complicates installation, requiring a through hull fitting and a seawater pump. There's no free lunch in boat refrigeration.
Ready-made Refrigerators
For the ultimate in simplicity, you can rip out your icebox and install a complete compact refrigerator, similar to the one you may have had in your dorm room in college. These usually utilize the same type of compressor system as units such as the Cold machine, and have the same power demands. The disadvantages are the same as the other electrically-driven systems. The only advantage is drop-in installation. Once again, best for dockside living and powerboats, although they're as easy to use as your home refrigerator.
Thermoelectric Modules
It's hard for us to believe that thermoelectric module refrigeration still exists. About a decade ago, it was touted as the latest space-age refrigeration technology, instant conversion of your icebox to a refrigeration system.
In our opinion, it should have stayed in space. Its only advantages are compactness, ease of installation, and low cost. Thermoelectric modules draw as much power as sealed compressor systems and have no freezing capacity. They will work only in a small, extremely well insulated box, and even then we don't think they're worth the trouble.
The one exception is the completely portable, self contained box such as the Koolatron Caddy. You ~ load it with food at the house, plug it into your car's cigarette lighter while you drive to the boat, then plug it into a similar outlet on your boat. As long as you have adequate power on board, it will do a reasonable job of keeping food cool for a weekend trip. You can then tote it home at the end of your cruise. Portable and inexpensive, but only suited to occasional short-term use.
Conclusions
These are the basic options for cooling food on your boat. Which you choose depends on your sources of power, how you use your boat, available space for the installation, your handyman capabilities, and the thickness of your wallet.
For a boat kept on a mooring and used only on week~, it may be hard to beat 50 pounds of ice at $2.50. For a cruise round the world, think instead of perhaps tens of hours of installation work, hundreds of pounds of equipment or batteries, and maybe thousands of dollars out of your wallet, Just how much do you want that cold drink or fresh salad? How rich do you feel?