By admin ~ May 4th, 2012. Filed under: Engine Room.
Watermakers make fresh water anywhere a realityBy Doug Thompson
When you’re cruising far from land or docked in a foreign port, a watermaker can make life aboard your boat very comfortable. The miserly use of water to stretch your holding tank can be a thing of the past, as your reverse-osmosis system turns raw seawater into drinkable fresh water.
Recreational marine watermakers came to the market more than 25 years ago, and since the processes have improved, equipment has become smaller and prices have dropped. Whether or not you need a watermaker depends upon your boating activities. If you’re a coastal U.S. cruiser and rarely stray from a port where fresh water you can trust is always available, then the need for a watermaker is small. But if you have a sportfishing boat and you make long runs before stopping to troll, or if you are out for days at a time or cruising to foreign ports, then a watermaker is a necessity.
Maintenance and technological improvements
Watermakers use a series of pumps, filters and membranes to turn raw seawater into fresh water. The current EPA standard for potable fresh water is under 500 parts of particulates per million, and all the manufacturers’ products in this article meet that standard. The process is reverse osmosis, the same process used on a large scale to provide fresh water in the United States and around the world at desalination plants. At the heart of the process is the membrane, which is a filter with pores the size of a red blood cell. After the larger particles in seawater are filtered out, a high-pressure pump forces water through the membrane, which removes almost all of the dissolved solids. This method rejects up to 99 percent of salts, contaminates and pollutants from seawater, until the water purity meets the EPA standard.
Biological growth when a watermaker is not in use can affect water quality. Heat and standing seawater is the ideal environment for biological growth, and that’s always been the bugaboo for watermakers: how to keep biologicals from growing used to involve flushing the system with acidic chemicals. Today, however, freshwater flushing keeps the membranes clean and greatly reduces maintenance.
“You want to look for a watermaker that comes standard with automatic flush,” says Scott Beard, General Manager of Beard Marine in Fort Lauderdale, a Sea Recovery watermaker dealer. “Freshwater flush is crucial to longevity of the membranes. You can also get a watermaker with manual flush, but there’s a downside compared to automatic. I’ve heard of people turning on the manual flush, forgetting about it and coming back the next day and the tanks are bone dry.”
Watermakers have also become smaller over the years—some are now the size of a large suitcase. Watermakers are also offered in modular configurations so the working parts can be installed where space is available. A key consideration is service, and you should choose a watermaker brand that has a broad dealer network in the area where you are doing most of your boating. Some watermaker companies use proprietary components that can only be accessed through their dealer network or from the factory, while others offer non-proprietary parts that may be more easily obtained worldwide.
Most boats 40 feet and longer will use watermakers run with AC-powered pumps, but there are DC-powered watermakers that are used on smaller power boats and sailboats. AC-powered systems deliver a more constant flow rate and higher pressure over a longer period of time, while DC systems are for boats with less demand and smaller water tanks.
Why have a watermaker
Water is heavy, 8.35 pounds per gallon, so a sportfishing boat embarking on a 50-mile run to the fishing grounds can save a lot of fuel by starting with minimal water in the holding tanks. Once you start trolling, the generator is turned on and the watermaker can start working, making all the fresh water you need while you spread out the lines and go for the big one.
“A 200-gallon water tank is common on a sportfishing boat, and 200 gallons at 8.35 pounds per gallon is over 1,600 pounds,” Beard explained. “That’s a lot of extra weight to push around going from Point A to Point B, so running with less water in the tanks should result in less fuel burned.”
Taking on water at a foreign port can be risky, and with a watermaker you eliminate that risk. As the planet becomes more polluted, the issue of getting clean water can be a challenge—but not if you can make your own water.