There was a time when reverse-osmosis (RO) watermakers were known for their expensive, temperamental manner. They required careful pickling and dedicated flushing; otherwise, the membranes would self-destruct, becoming choked in microorganisms and hopelessly corroded.
Today, watermakers more closely resemble the trusty diesel engine. If you care for their basic functions – changing their filters and checking for ample pressure and clear water flow – they will last many thousands of hours without so much as a rebuild.
While watermakers still need dedicated care to prevent major damage, that care has become surprisingly easy since the number of moving parts has decreased, and due to automation, the machines can alert the owners of potential trouble, even shutting down to prevent damage if the problem is not imminently solved.
“This industry has made real strides in the last decade,” said Ray Carter, sales manager for Spectra Watermakers of San Rafael, Calif. “You used to hear real horror stories, especially with the chemicals involved in the pickling process that, if done wrong, could cost you a $3,000-membrane. Now, I leave my boat for a week, two weeks, even a month, since the machine takes care of itself, flushing with fresh water every five days.” Carter’s Spectra is installed “between the main engines” on his trawler, a California 34. He is based in Seattle, and he frequently cruises the San Juan Islands, which he said would include frustrating searches for water – expensive water – if his vessel weren’t so equipped.
“People who don’t have watermakers have a hard time finding good water around here. It’s like the Caribbean, where you can spend 60 cents a gallon for water – not even good water,” Carter said. “A watermaker is becoming essential equipment for a lot of people.”
Spectra watermakers enjoy some well-known customers, including the now-fastest sailboat on the planet, the French cat Orange II, which recently completed a record-breaking circumnavigation in a little more than 50 days. The vessel was equipped with two Spectra Cape Horn Xtremes, one in each hull, Carter said. As did seven of the eight Volvo Ocean Race boats – “The one that didn’t, came in dead last!” Carter reported – and five of the newly built Volvo boats are similarly equipped.
Three important elements
The Cape Horn Xtreme and the company’s more basic models – including the Catalina 300, the choice of the long-distance voyager – each feature three of the company’s important systems. First, there’s the Clark Pump, also called the intensifier, which is a high-pressure amplifier that is used in all the company’s units, from 200- to 1,000-gallon-per-day (gpd) models. Fed by a low-pressure feed pump, the Clark draws very little power (1 amp-hour per gallon of water, depending somewhat on seawater temperature), while maintaining 800 pounds per square inch (psi) and running seawater through the membrane on both strokes of the double piston. Other watermaker companies tend to use conventional triple-piston Cat pumps.
Then there’s the MPC 3000, the computer that makes the watermaker behave. The MPC (microprocessor control) monitors all the machine’s vital signs, from the seawater flow at the sea strainer to the various stages of filters. It monitors voltage and will shut itself down if voltage drops or if filters clog. The MPC also will ensure a freshwater flushing of the system when the watermaker is not in use.
Lastly, there’s Spectra’s Z-Brane and Z-Guard technology, which use an electrode to maintain an electrostatic field within the watermaker, positively charging the water molecules to prevent formation of sludge, scale and biofouling. Equipped with a Z-Brane, a Spectra watermaker reportedly needs no pickling. To be stored or winterized, it can be flushed with propylene glycol (nontoxic antifreeze). Carter said an estimated 30 percent of all Spectras sold now feature the Z-Brane, which costs about an additional $1,600, depending on the model. Spectra offers three basic models for long-range small-boat sailors, three 12-volt 150- to 330-gpd models, and three 24-volt 330- to 1,000-gpd models. Spectra also offers 110- and 220-volt AC models.
From recreational to commercial
Horizon Reverse Osmosis, based in Carson, Calif., claims to be the largest watermaker manufacturer in the world, providing watermakers for 30-foot recreational vessels up to 400-foot commercial vessels. The company prides itself on its machines’ rugged, all-stainless-steel construction. The feed pump is 316-stainless, and the energy transfer device, the high-pressure pumping mechanism, is made of Nitronic 50, according to CEO Stephen Rollins.
The short chamber and more frequent cycling of the energy transfer device minimizes pressure fluctuations, allowing it to deliver a relatively steady flow of feed water across the RO membrane, which results in higher-quality product water and better salt rejection, thus extending the life of the membrane by minimizing scaling (salt deposits). “This is essential to keeping the membrane from fouling,” Rollins said. All HRO watermakers are designed for 1,000-psi operating pressure with a 3-to-1 minimum burst-safety factor, which means that all high-pressure components withstand a minimum of 3,000 psi, Rollins said.
“Most sailors are obsessed with minimizing amp draw. And that’s laudable. But at HRO Systems, we put our energy into durability and engineering,” Rollins added. For mariners who are primarily concerned with the lowest amp-hour-per-gallon ratio, Rollins said the company’s Seafari Escape models (200 to 600 gpd) are the product of choice, consuming as little as 1.3 amps per gallon. Those concerned primarily with ticket price should consider the conventional models, which are equipped with a standard, albeit also all-stainless, plunger-type high-pressure pump and are capable of delivering 170 to 1,800 gpd. With fully automatic flushing, the units draw anywhere from 13 to 22 amps, depending on size and water flow.
Village Marine Tec. has pioneered watermaking in the commercial marine market, providing large units to the U.S. Navy and Coast Guard as well as other commercial applications. The company’s popular Little Wonder series, though, offers 12-volt systems capable of delivering from 160 to 350 gpd. Village Marine offers both framed (enclosed in a paneled box) and unframed models for mounting on a bulkhead. The company also sells engine-driven models.
Computer controller
FCI Watermakers also offers a fully automatic freshwater flush system and monitoring computer for its line of watermakers. The UROC (Universal Reverse Osmosis Controller) displays pressure, temperature, production rates, water quality and electrical information. The computer also includes alarms for pressure, water quality and power use. FCI, like many watermaker companies, sells unique accessories to their watermakers, including a remote, offsite monitoring computer and various post-RO filters and water sterilizers. FCI’s Aquamiser Plus model, an engine-driven unit that can be purchased in a frame or for mounting on bulkheads, comes in 200- to 800-gpd models.
On the other end of the watermaking spectrum – for those who want exercise while making water – are the hand-powered models offered by Katadyn. The Survivor-06 and Survivor-35 produce a half gallon and 1.2 gallons of water per hour respectively and are excellent emergency devices for those who take to the life raft or face similarly unfortunate circumstances. The 06 weighs just 2.5 lbs, and the 35 weighs 7 lbs.
Katadyn also offers 12-volt watermakers, from the PowerSurvivor-40E (12 volts/4 amps, 36 gpd), which has manual backup for emergencies and can be rigged for a 24-volt system, to the PowerSurvivor-80E, which draws 8 amps and produces just over 80 gpd. Each of the systems comes in either a framed box or ready for bulkhead mounting in tight spaces.
Whatever your choice of watermaker, the devices have come a long way. They work better and last longer the more you use them, which means that daily showers are des rigueur for many offshore boats.
Bruce Schwab, who recently completed the Vendée Globe round-the-world race with a Spectra Watermaker that draws its power from a set of Solara panels, reported that the machine worked flawlessly aboard his Open 60 Ocean Planet. He changed the filters regularly, but in the open sea found they rarely needed it.
“I am rather wasteful with our fresh water,” Schwab said, “because I wind up with so much of it!” A nice problem to have.
Contributing Editor Twain Braden is currently based in Charleston, S.C.
