Offshore Log:
Life With The Little Wonder

After three months and 1,000 gallons of water, Calypsos crew pauses to consider the many issues involving watermakers… from installation to cost, maintenance, operation, water quality and engine-run time.


The search for potable water is the bane of the long-distance cruisers existence. In the US, we take cheap, easily accessible water of decent quality for granted. At best, you belly up to a floating dock and fill the tanks for nothing. At the worst, you go to the fuel dock, buy a few gallons of fuel, and still probably fill up the water tanks for nothing.

In much of the rest of the world, it aint so easy. Quality drinking water is a commodity-one that you pay for, when you can find it.

During the winter and spring of 1998, many of the islands of the Caribbean were suffering from drought, perhaps the by-product of a bad El Nino year.

Water was expensive-from a low of about 10 per gallon to a high of about 25 per gallon-and often it was of questionable quality. You may argue that for a two-person cruising boat using 10 to 15 gallons a day, that amounts to only about $3.75 per day at worst. Over the course of a year, however, it adds up to between $375 and $1,300.

By contrast, the approximately 35,000 gallons of water that we used in our house ashore every year cost about $700.

More significant than the cost, however, is the inconvenience. Our experience has been that most cruising boats crewed by couples fill water tanks every two weeks. This magic number seems to be independent of boat size or the amount of tankage! If you have big tanks, you tend to use a lot of water. If you have small tanks, you use less.

In either case, before two weeks are up you start nervously looking for the next water source.

Since late January, virtually every drop of freshwater we have used aboard Calypso has been produced by our 12-volt Village Marine Little Wonder watermaker. I say virtually because in April we put into the Moorings Secret Harbour base in Grenada for a few weeks while making a trip back to the US. We took advantage of the readily available freshwater (15 per US gallon) to do a more thorough cleaning of the boat, including a detergent and bleach cleaning of the teak decks, than we could otherwise justify. Complete cleaning of the exterior of our 40-footer, including the hull, decks, and superstructure, takes about 100 gallons of water.

The Little Wonder has, without exaggeration, changed our lives. Relying on the watermaker has freed us from the search for water. At the same time, relying exclusively on the watermaker has imposed its own discipline on our cruising. We watch where we anchor, choosing the cleanest section of harbors. We religiously run the watermaker daily to keep up with our energy and water budgets, and to minimize maintenance of the machine. To the routine of checking the raw water strainer, oil level, coolant level, and water temperature of the Perkins diesel, we have added the routine of checking the water strainer, pre-filter, product water quality, operating pressure, and flow rate of the watermaker.

Choosing a Watermaker
By the time I figured out that a watermaker was a practical piece of gear on a 40-foot sailboat, Calypsos engine compartment was jammed full by the engine, compressor for the Sea Frost refrigeration system, and a big Balmar alternator. There was no room to install an engine-driven high-pressure watermaker pump without major re-engineering, something I just couldnt face after almost a decade of construction.

A 12-volt watermaker was the only logical solution.

Fortunately, low-voltage watermakers have come a long way in the last 10 years. As we reported in the December 1997 and January 1, 1998 issues of PS, you can now get 12-volt watermakers producing almost 10 gallons per hour-provided you have the electrical capacity to feed them.

In our testing, Village Marines Little Wonder proved to be a solid performer with a successful long-term track record-important criteria for a long-range cruiser.

Storage space on any cruising boat is at a premium. Ideally, a watermaker would be installed in an otherwise-unused space, one that is easily accessible for service. In practice, such a space rarely exists. If its easy to get at, it has already been used.

In our case, the storage space under the forward section of the U-shaped dinette was sacrificed to the watermaker. This area-almost 5-1/2 cubic feet of beautiful, accessible storage, which had been the tool locker-would just accommodate the self-contained Little Wonder, its booster pump, freshwater flush system, pre-filter, hoses, and wiring, with space to hold all the spares (filters, cleaning chemicals, pump overhaul kit) needed to keep things going for a multi-year cruise. A modular system would have taken up less space, and in our case would have been no more complex to install. We would have ended up spending a lot of time, however, figuring out how to partition off and utilize the remaining volume, so its probably just as well that we selected the self-contained, frame-mounted machine.

Because the bottom surface of the mounting space was not quite big enough to mount the Little Wonder by simply bolting it down, I fabricated mounting brackets from 1/4″ thick anodized aluminum angle and flat stock to level the watermaker and raise it as high in the locker as possible. This aluminum angle, as well as flat stock, round and square tube, and other shapes, is available in many large hardware stores, and is an incredibly useful item around the boat.

The end result was a somewhat more complicated installation than a simple bolt-down, but one that gives a storage space under the machine for cleaning chemicals and spare parts.

The self-contained version of the Little Wonder is not a zero-clearance installation. All three water hoses-feed water, product water, and reject brine-lead to one end of the machine, so you need at least several inches of space to make connections via hose bends or elbows at that end.

The wiring, too, must be led through a cutout in the back of the machine, and requires an inch or so of clearance to accommodate the heavy wiring required.

Likewise, removing the aluminum cover requires access to a series of machine screws on all sides of the unit. We ended up leaving out some of the securing screws, and replacing others with hex-head fastenings that require less access clearance. Many people simply throw the cover away, but it does offer protection from dirt and dust, as well as keeping your hands out of the drive belt.

Any watermaker should have its own raw water inlet, preferably placed far from any other through hull fitting, and as low on the hull as possible to minimize the possibility of sucking air into the system when the watermaker is used under sail. In our case, the flush through-hull, with an Apollo ball-valve seacock, was installed in the bilge just opposite the watermaker compartment, resulting in a fairly short hose run to the machine.

The feedwater seacock is just beneath a lifting section of the cabin sole, making it easy to open and shut the valve every time the machine is used. This is a critical safety consideration in our case, since all the raw-water plumbing for the watermaker is below the waterline. With about a dozen below-water hose connections in this one plumbing line, I would never sleep with that seacock left open.

A Groco ARG-500 raw water strainer eliminates grass and other large particulate matter before it gets to the pre-filter.

Because of space limitations, we use a single 5-micron pre-filter downstream from the seawater strainer. The only disadvantage of a single pre-filter is that the fine filter elements clog more quickly than they would with a two-filter system incorporating coarse and fine elements.

Concentrated brine from the watermaker is discharged overboard through a Forespar Marelon seacock with a non-metallic skin fitting, located above the waterline. I chose non-metallic fittings for this portion of the plumbing for fear the concentrated brine would quickly corrode even high-quality bronze fittings.

Village Marine makes a freshwater back-flush system for about $150, which incorporates a filter canister and three-way valve. We would not consider installing a watermaker without a freshwater back-flush, because it dramatically reduces the maintenance required by the machine.

Freshwater output flows from the machine to a three-way valve that is part of the boats main freshwater manifold. This valve diverts water to a spout mounted at the galley sinks. The spout is one of three incorporated in a single custom stainless steel fitting. The other two spouts are the vents for the freshwater tanks.

After startup, the watermaker is run for five minutes with water diverted to the sink. At that point, we taste it to make sure water quality is satisfactory, then turn the three-way valve in the manifold (mounted in the locker under the sink) to route the water into one or both of the water tanks.

We draw water from one tank while filling the other. This allows us to monitor both water use and water production.

Plumbing product water into the main tank manifold was probably a mistake. If the tanks contained chlorinated water, it could theoretically be drawn back into the watermaker membrane at shutdown, eventually ruining it. In practice, we divert water back through the sampling spout before shutdown, eliminating the possibility of back-siphoning.

I intend to build a separate watermaker manifold, plumbing product water into the tank vents rather than into the main plumbing manifold. This will both reduce back-pressure and eliminate the possibility of back-siphoning into the watermaker. The tank vent hoses are large enough to accommodate the relatively low product water flow without compromising the function of the vents.

Electrical Requirements
A big 12-volt watermaker needs a lot of juice. The Little Wonders 1/4-hp. motor is actually the smallest used by any high-capacity unit except the extraordinary Spectra. With its booster pump, our unit draws 18.6 amps.

Any 12-volt equipment using an electric motor-a windlass or bilge pump, for example-should be wired for a voltage drop of 3%. Other than a windlass, the motor of a 12-volt watermaker is likely to be the biggest constantly used current hog on the boat.

We wired with 8-gauge duplex wire. In retrospect, it would have been better to use 6-gauge wire, as the actual current drop in our system is about 4%.

The Little Wonder has an internal 25-amp breaker to protect its wiring and motor. We wired our machine through the main breaker panel, in a dedicated circuit with a 30-amp breaker. Connections between the big duplex wiring for the watermaker and the jumper from the electrical panel are made through a 65-amp terminal block.

The motor runs very hot. You can barely hold your hand on it after it has been running for a half hour. While the Little Wonders cover is hardly airtight, it does virtually eliminate air flow around the machine. Removing the cover and venting the mounting compartment would probably make the motor run cooler, but it would make the cabin a lot noisier. Because a Village Marine technician told us the motor is intended to run hot, we are not worrying about it for now.

Water Production
Our water production has averaged about 5.5 gallons per hour. This has been fairly constant. The normal feedwater temperature in the Caribbean is about 81F. High feedwater temperatures, as a rule, result in higher output rates.

Village Marine rates product output for the 1/4-hp. Little Wonder at five to six gallons per hour. Our production of 5.5 gallons is squarely in the middle of this range, but variances of plus or minus 10% to 15% from the rated output are considered normal.

A Water and Electrical Budget
Before installing the watermaker, we used an average of 12 gallons of freshwater per day. This included daily showers, cooking, dishwashing, and general cleaning.

Since installing the watermaker, our average consumption has increased slightly to about 14 gallons per day. The extra water usage goes into more thorough on-deck cleaning, and is partly the result of the fact that we are sailing the boat a lot, and now have the water to wash some of the salt off when we get in at the end of the day.

We went through a heady period where I washed off the anchor chain and anchor with freshwater every time it came aboard, but the 15 gallons that used was extravagant, especially when we were re-anchoring daily. Now, only the part of the chain that has been lying on the bottom gets a freshwater wash, unless the boat has been anchored for more than a few days, or has been anchored in a gooey bottom.

To maintain a constant-balance water budget requires operating the Little Wonder for about 2-1/2 hours per day, using up 47 amp-hours of electricity. This is almost the same amount of electricity that we use for everything else when the boat is at anchor.

In the tropics, our engine-driven freezer/refrigerator requires slightly less than 1-1/2 hours of engine operation per day in order to keep the freezer section rock-hard. It will actually hold over for 18 hours before the first plate thaws, but running the engine twice per day guarantees that everything stays frozen.

Generally, we run the watermaker at the same time the engine is run for the freezer and battery charging. The heavy electrical load of the watermaker keeps the alternator, controlled by a Link 2000R regulating system, operating at a higher output level for longer, actually increasing the efficiency of our charging regime while keeping the engine more heavily loaded. The higher voltage of the system while the alternator is charging makes the Little Wonders motor happier.

Because 1-1/2 hours of engine operation would not be enough to keep up with our water use, we generally run the watermaker for an hour before the evening charging session, as well as while the engine is operating. This results in a slight daily electrical deficit. At this time, the electrical deficit is made up when we are at anchor by running the engine for an extra half hour every third day or so.

If we had a small solar panel, we could reduce the engine running to only that amount required by the refrigeration: perhaps 1 hour and 15 minutes daily. As it is, the boats entire energy management scheme is still experimental, and is being constantly re-evaluated.

Having the watermaker aboard requires, at worst, an additional half hour of engine operation per day. At charging rpm, this means 1/4 gallon of extra fuel burn per day. At Caribbean fuel prices, this costs about 50 per day extra for fuel, plus the wear and tear on the engine. An extra half hour of engine operation daily would add up to an additional 183 engine hours per year-roughly two oil changes, at around $15 per oil change, including oil and filter.

We have found that it is reasonably easy to keep a zero-loss water budget. If we start from scratch, with empty tanks-as we did-it is more difficult to get ahead on water production, so that you actually fill up the tanks, producing more water than you use.

On the few occasions that we have motored from one place to another, we run the watermaker almost the entire time…if the water is clean. The most water we have made in a single day was 30 gallons, when we motored in a flat calm from Grenada to Carriacou.

Water Quality
The water produced by the Little Wonder is at least as good as any water we bought in the Caribbean before installing the watermaker. Since it still contains about 250 ppm of dissolved solids, it is not quite as tasteless as distilled water. (Incidentally, the Little Wonder can be used to produce ultra-pure water suitable for use in liquid electrolyte batteries by running freshwater through the machine and adjusting the pressure regulator to very low pressure.)

At this time, we do not add any chlorine to our water tanks, because we are making all our water and consuming it as we go. It never gets stale in the tanks. After drinking water from the watermaker for months, the taste of chlorinated city water is remarkably chemical and strong.

Except for some notably dirty harbors, such as St. Georges, Grenada, the waters of the Caribbean are remarkably clean. We filter all our drinking water through a Seagull IV water filter, but use water straight from the tanks for cooking and washing.

When in harbors with a large number of boats, we do not run the watermaker during the early morning hours, when people are more likely to be flushing their heads overboard. Holding tanks are never used here.

The thought of constant maintenance scares a lot of people away from watermakers. If you use the machine daily, the maintenance is surprisingly low.

In the first two months of use, I cleaned grass out of the water strainer twice, and replaced the 5-micron pre-filter once. Once a week, I back-flush freshwater through the system, just for the heck of it. Thats it for routine maintenance.

When I laid up the machine during a multi-week trip to the US, I pickled the membrane-about a half hour of work, because it was the first time I had done it.

The Little Wonder is designed to be started under pressure, which greatly simplifies operation. To use the machine, we open the seacock and flip on the power at the main electrical panel. After water is diverted to the sink for five minutes, we taste it, then divert to the tanks. Shut-down is simply the reverse of the procedure, with a final tasting to make sure that the water you have been making is still good.

Every other day, I open the watermaker compartment while it is running to check system pressure and product water flow on the gauges.

As of April 1, Calypsos Little Wonder had produced almost 1,000 gallons of freshwater. It has proven to be a low-maintenance, reliable companion.

If I were doing it again, I would probably install a slightly larger machine using a 1/3-hp. motor, to get output up to 7 or 8 gallons per hour. With that scenario, the watermaker would only be operated when the engine was running, because the 26 or so amps such a system would draw without the alternator charging would pull voltage down to a level that would reduce the efficiency of the motor.

For a two-person cruising boat, the 1/4-hp. Little Wonder is just about the right size. Having it has simplified our lives, rather than complicating them.

A large percentage of the American cruising boats the size of Calypso we have been aboard this year have 12-volt watermakers. Most of those that don’t have them are considering installing them.

A high-output 12-volt watermaker is not a cheap installation. The list price of the 1/4-hp., self-contained Little Wonder is $3,200, with a typical street price of about $2,900. To that you can add $150 for a freshwater back-flush, $145 for the feedwater boost pump, and perhaps $300 in installation parts such as through hull, seacocks, strainers, hose, hose clamps, and fittings.

Assuming you do the installation work yourself-it only requires thought, planning, and a modicum of skill-your all-up cost should be about $4,000.

You may argue that you can buy a lot of water for $4,000, and there is no denying it. What youre buying, however, is not just water. Its freedom. Freedom from the search for water, and the hassle of getting it to the boat. Freedom from questionable water sources. Freedom from reliance on the shore. And freedom is what long-term cruising is all about.

As we continue our cruise, well update you on our watermaking experiences.

Contact- Village Marine Tec, 2000 West 135th St., Gardena, CA 90249; 800/421-4503.

Darrell Nicholson
Practical Sailor has been independently testing and reporting on sailboats and sailing gear for more than 50 years. Supported entirely by subscribers, Practical Sailor accepts no advertising. Its independent tests are carried out by experienced sailors and marine industry professionals dedicated to providing objective evaluation and reporting about boats, gear, and the skills required to cross oceans. Practical Sailor is edited by Darrell Nicholson, a long-time liveaboard sailor and trans-Pacific cruiser who has been director of Belvoir Media Group's marine division since 2005. He holds a U.S. Coast Guard 100-ton Master license, has logged tens of thousands of miles in three oceans, and has skippered everything from pilot boats to day charter cats. His weekly blog Inside Practical Sailor offers an inside look at current research and gear tests at Practical Sailor, while his award-winning column,"Rhumb Lines," tracks boating trends and reflects upon the sailing life. He sails a Sparkman & Stephens-designed Yankee 30 out of St. Petersburg, Florida. You can reach him at