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Watermakers reduce water supply worries

Jan 1, 2003

Boaters who have voyaged for any length of time know the frustration that results when the water tanks run low. When you are on the move, voyaging to a different anchorage daily, this is a simple matter of stopping at the next marina to top off the water tanks. (You should, out of courtesy to the marina, purchase fuel at the same time.) The true frustration arises when you stop moving on a daily basis or you leave the U.S. When you drop the hook for an extended stay in any location, you must start carrying water to the boat by dinghy, in heavy plastic jugs. Outside the U.S. it is not uncommon to purchase water that is usually less than potable. Regardless of whether you must pay for the water, you have better ways to spend your days than in transporting water from a spigot to your boat. One method that can be used to eliminate the cost and carrying of water is the installation of a watermaker. These devices turn salt water into water fit for human consumption. They do have some drawbacks, as do most mechanical devices: They are maintenance intensive, use batteries or the engine for power, and the membranes are costly to replace. If you leave the unit out of service for any amount of time, it must be placed in storage, or bacteria growth will render the unit useless. Most important, they cannot be used in certain water conditions (water that is silt-laden or polluted). I suggest the installation of these units only to voyagers who regularly travel in reasonably clean water. If you are one of these voyagers, a watermaker will be an excellent choice for your water needs. The high-pressure pump of the unit can be powered by batteries or the engine. Watermakers are available in sizes that produce a few gallons in a 24-hour period of operation to several hundred gallons in that period. When choosing and sizing a unit for your needs, consider these points. The average water consumption for a crew of two is six to 10 gallons a day. Engine-driven units will decrease your daily electrically needs, but require you to run the engine more often. If you use the engine to charge batteries or for refrigeration, there is virtually no added engine cost to operate this unit. If you run a generator regularly, a 110-VAC unit may be the best choice. However, the watermaker must be capable of producing the quantity of water needed in the period of time you normally run your engine or genset. As an example, considering a crew of two using 10 gallons a day: If the engine or genset must be used to charge the batteries for four hours every three days, the watermaker must be capable of producing 30 gallons of water in that four-hour period. This is a large watermaker that has a large "footprint." The size of the unit must be considered as there are many boats that have limited space available for the installation of additional equipment. Each system on a boat works in conjunction with the other systems on the boat. If you opt for a 12-VDC-driven watermaker, your batteries must have the capacity to run the unit. This may necessitate larger house battery banks with a larger alternator to charge the banks. All aspects of the system installation must be taken into account before the final choice can be made. The manufacturers of the units being considered for installation will provide unit specification details in their catalogs. This is the starting point for choosing the unit that will serve the required need and will operate within the limitations of the boat's system. When the choice has been narrowed to a few suitable units, contact the manufacturers for installation literature before purchasing any unit. This step will aid in making the final decision on the proper unit. There are many methods that can be used to install and plumb the unit into the boat's water system. Many of these methods are dictated by the chosen unit. The first step in any installation is to read, understand, and follow the literature supplied with the unit. Follow the installation literature and the following guidelines to ensure a safe, professional installation. Sea water must be routed to the unit from a through-hull fitting, with an outboard strainer and lever shut-off valve (seacock) located well away from any waste or bilge-pump discharge through-hulls (check this very carefully!). Next in line is a high-quality inboard strainer. The hose is run from the strainer's outlet port to the unit. The discharge line from the unit should be run to the water tanks. This can be accomplished by many methods, all of which are dependent on the type of tank and piping system used in the boat. Choosing the best method for this connection may require a consultation with a qualified professional installer. A caution: Unless otherwise noted by the manufacturer, all hoses used in this installation must be wire-reinforced water hose. All fittings, both above and below the waterline, must be double clamped. The water supplied by the watermaker is untreated water, and if it is not used in a few days it will become contaminated with bacteria. To prevent this, add about one teaspoon of non-scented chlorine bleach per 10 gallons of water in the tanks. This is not a precise or scientific calculation, but it has always worked for me. Place a charcoal/sediment whole-house-type filter in the plumbing line directly after the freshwater pressure pump. This will eliminate foreign particles and the taste of the chlorine. It will not, however, purify the water. If you prefer, as I do, to have purified water for drinking and cooking, a water purification unit can be installed. This unit should be placed using a tee fitting in the cold-water line at the galley sink and run to a separate faucet. If you choose to use only purified water on board, the unit should be installed immediately after the whole-house filter. If you do decide to install a purification unit, I strongly suggest using a unit that covers a broad spectrum of contaminant reduction and germicidal disinfection. After these units have been installed, you canand shouldlearn how to maintain them. There are several areas of concern when readying a watermaker for operation after it has been out of service for any length of time. All the manufacturers agree on one point: properly placing the unit into hibernation will eliminate any problems when the time arrives to start the unit. Many feel that if the unit is stored properly the only start-up procedure is opening the valves and turning it on. This is true of most units available today, but, being of the old school, I feel a few other precautions should also be attended to before the switch is thrown. Call me a fanaticmost people do. A unit's storage and start up procedures vary by manufacturer. Therefore, I will not delve into the exact procedures for any given unit. The following guidelines are a combination of many manufacturers' suggestions for the proper procedures. Following these guidelines and strictly adhering to the owner's manual instructions for your unit will assure you the watermaker will operate when you require its services. When taking the unit out of service, follow these suggestions:1. Never close any supply or discharge valve while the unit is running.2. Reduce the pressure to zero before disconnecting the power.3. Flush the unit with fresh water to minimize bacteria growth in the membrane and the balance of the system. Long-term storage, over six weeks, usually requires the use of a factory-approved chemical. (This procedure is commonly referred to as "pickling.")Winter lay-up requires a more thorough shut-down procedure that varies tremendously by manufacturer. Depending on the type, size and manufacturer of the unit, several or all the following must be accomplished when placing the unit into service.1. Observe the inlet pressure readings. Low inlet pressure readings will indicate a clogged sea strainer or filters. Replace or clean these items according to the manual.2. The brine flow rate must be checked to ensure it is within acceptable limits. Poor brine flow rate is indicative that a high-pressure pump seal has failed. When the flow rate is at an acceptable level, the high-pressure side can be increased slowly until it has reached its rated output.3. If the water produced is over the acceptable "parts per million," the membrane may require replacement.4. Continue to check the system for any signs of oil or water leaks at all the connections.5. Check all the hoses for signs of deterioration, abrasion, cracking, etc.6. Check all electrical connections and wiring for deterioration, abrasion, corrosion, fraying, etc.Additionally, some units require priming of the system, flushing the system with fresh water after it is operating properly, lubrication, belt adjustment, and various inspections particular to the specific units. When the unit is operating properly, it would be wise to run it for several cycles to ensure continued trouble-free operation. It is always easier to repair a unit while stateside with a vehicle and suppliers at hand than it is to locate parts and repair the unit in a foreign port. Be certain you have ample spare parts on boardmembranes, filters, o-rings, oil, etc.before departing for an extended cruise. Any authorized dealer can put a package of spares together for the unit.With the watermaker in place, the days of looking for water and carrying water are in your past. Taking a long hot shower on board, without guilt, will be your future.