Like any investment in onboard equipment, watermakers spark debate between their users and their detractors. This month we'll examine the technical aspects of producing water onboard, unit choices and power consumption. Echo Marine Ltd. in Trinidad, makers of the ECHOTec onboard desalinization systems, supplied the technical information, keen to assist All at Sea in our effort to "lift the fog" on watermakers.
Choosing the Right Unit
We focused our search on units for sailing yachts in the 40-50 foot range, fitting out for long-term liveaboard cruising, away from facilities where water is easily obtainable. Incidentally, this is exactly the market that ECHOTec targets, according to managing director Michael Bauza. A yacht on such a voyage must be very self-sufficient, and the ability to make water on board is an obvious advantage.
Bauza stresses simplicity: "The sailor should not be a slave to his equipment onboard. His equipment should instead enhance his freedom. ECHOTec was in the business of repairing watermakers for a full eight years before starting to build our own, armed with the knowledge of what doesn't work in an onboard system."
ECHOTec produces several ranges of watermakers, from AC driven units for use on yachts with generators, to DC units that run off the yacht's battery bank – the most versatile, where a multitude of charging options exist, including solar and wind power – and belt-driven units, ideal for smaller boats that use their engine as their main source of charging power.
Bauza made it clear that each of ECHOTec's systems use the same, electronic-free technology to produce water – specifically, a reverse osmosis procedure that utilizes a high-pressure pump to push water through a special membrane – the only difference being the power source.
A belt-driven watermaker, where the high-pressure pump is mounted directly on the engine (in similar fashion to an alternator), can produce up to 60 gallons per hour while the engine simultaneously charges the batteries.
Echo Marine acknowledged the need for computerized and automated systems in the commercial market, where a watermaker may be running 24 hours per day and producing upward of 10,000 gallons, and ECHOTec produces these. "These complicated and intricate systems just have no place on a yacht," says Bauza. "The sailor wants to be able to perform his own maintenance and enact his own repairs when off in a deserted corner of the globe, which is just not possible on many 'fancy' systems nowadays."
The biggest concern with many cruising yachts is "power in v. power out." Power consumption varies according to the power source of a desalinization unit. According to ECHOTec, a high output AC-powered unit – running off a generator – requires 19 amp/h on a 120V system. This power input yields up to 60 gallons of freshwater per hour, and requires a minimum 4.5 kilowatt generator to operate. Low capacity AC units, which produce upward of 13 gallons per hour, require only a 1.5 kilowatt generator or a medium-sized inverter.
A belt-driven system uses about 2.5 HP of the engine's power output. Bauza noted that the addition of "load" on the engine actually helps to prevent the buildup of carbon that occurs when an engine is run under low loads, i.e. for charging batteries at anchor.
Next month: the initial investment, installation and long-term maintenance required for an onboard watermaker.
Andy Schell is a professional captain and freelance writer, based in the Caribbean, Annapolis and Stockholm, depending on the season. Contact him at email@example.com or www.fathersonsailing.com.