What Size Marine Watermaker is right for my Boat?

Marine watermakers should provide ample fresh water to all passengers onboard on a daily basis. As a guideline, the U.S. Coast Guard recommends that 30 gallons of water per person per day should be available onboard. So, for example, if you are planning to have 4 people onboard, then you should plan on having 120 gallons of water available per day.

Calculating the Amount of Water Needed

When calculating the amount of water you will need don’t forget to consider all the uses.

Salt water can be used for:

  • Taking showers (but you’ll want to rinse with fresh water at least once at the end)
  • Washing dishes
  • Cooking (this depends on what you are cooking)
  • Washing your hands

You’ll use desalinated water for rinsing the decks, cooking, showering, and drinking. Remember to calculate the drinking water you bring in bottles as well as your storage tanks.

For an easy and quick calculation on how much water you need you can use our calculator on our homepage here. (scroll down to the section called “How Much Water Do You Need.”)

How Long to Run the Watermaker

Next, determine how many hours per day you want to operate the watermaker to make the capacity that you need. Most people are comfortable with between two and five hours per day.

Then, compute how many gallons of water you need to make per hour to make your daily demand considering the period of time you would want to operate the watermaker. Considering the example above, if a person wanted to make 120 gallons of water in a two-hour time period, then a watermaker capable of producing 60 gallons of water per hour is required.

This survey report shows some interesting facts about water onboard yachts.

Marine watermakers are rated based upon how many gallons of water they are capable of producing per hour. This information is also stated in terms of daily production (that is, the rated hourly production multiplied by 24).

WaterMaker Output

Marine water makers are typically available in ranges of production from eight to 344 gallons per hour (that is 200 to 8,300 gallons per day). Larger commercial-sized systems are typically available in outputs up to 1,750 gallons per hour (42,000 gallons per day). Unlike competitors, FCIWatermaker units are engineered to deliver the advertised output under varying conditions.

Can you give me guidance on marine water maker parts and accessories I don’t need?

We believe marine watermakers should come fully functional without needing to purchase additional accessories. Some unnecessary items include an oil water separating cartridge and an on-system UV sterilizer. The theory on the cartridge is that it will remove oil from the water before it hits the water maker membrane, but since water is pulled from below the surface where oil floats, the component ends up being a frivolous design feature that you end up paying to replace because the owner’s manual tells you it naturally degrades over time. In 30 years of manufacturing, we’ve never seen a membrane that has been dulled by oil build-up. Similarly, for a UV sterilizer to work properly it should be put in the discharge side of your fresh water holding tank. But competing manufacturers mount it on the intake side as part of the water making system, presumably to sterilize the water before it hits the tank. Because holding tanks are vented (inviting potential for contaminants) and are also fed by dockside fillings from shore, the holding tank itself could be contaminated with algae or bacteria. So, it makes no sense to take the extra step in purification if the UV sterilizer is placed before the holding tank.

Other things to look out for when buying a water maker are:
— systems that require proprietary components, such as membranes, pumps and fittings that are harder to find and more expensive to replace;
— water maker systems that use inferior materials, such as plastic versus high-grade stainless steel or bronze;
— special tools that are required for assembly or calibration;
— and compact systems that are completely enclosed in a frame that inhibits easy service and maintenance, such as changing the oil or replacing a fitting.

What parts and features should come standard with my marine water maker system?

Many manufacturers require users to buy packages of components to ensure full-service operation of their marine water maker. For example, a fresh-water flush is a necessary watermaking function included in every FCI system, but other manufacturers often sell this feature separately. With FCI’s inclusive pricing on our watermaking systems, you don’t need to buy add-ons, accessories and upgrades to achieve advertised outcomes and superior performance. What’s more, FCI systems come fully calibrated so you can enjoy quick water satisfaction, versus other brands that require the purchase of additional accessories or calibration solutions to complete the set up.

Do I need a ultra-violet sterilizer with my watermaker?

No, it is not a necessity, but can be beneficial as UV sterilizers remove approximately 99.9% of any biologicals from fresh water. With that said, proper placement of a UV Sterilizer is after the holding tank, not immediately after the watermaker, as specified by other manufacturers and/or installers. The reason for this is that in addition to receiving clean water from the on-board watermaker, holding tanks are vented (inviting potential for contaminants) and are also fed by dockside fillings from shore— there is no control of water quality in the holding tank itself. If a UV sterilizer is used, it should be sized to accommodate the requirements of the boat’s fresh water pump.

Is it possible to control the watermaker from the helm station?

FCI offers UROC technology for digital remote control/monitoring as an accessory for all of its systems. This is remote control in the true sense of the word, and not a glorified “on/off” switch that is typically offered on many other watermaking products. For instance, with FCI ‘s Universal Reverse Osmosis Controller on our Max Q systems, the user can monitor all system readouts from a backlit digital display. The remote control also enables the user to troublshoot, and program set points, automatic shut-off parameters and fresh water flush times without going to the main system.

How long should I expect a marine RO system to last?
  •  The life expectancy of a water maker varies by manufacturer. Brands that use lesser quality components or those that have inferior designs will obviously not last as long as those brands that have superior designs and utilize top-quality components. FCI Watermakers designs are second to none, using only the finest quality components. The life expectancy of an FCI marine watermaker system should be 20 years or more of trouble-free service, provided the unit receives proper maintenance according to the owner’s manual. Plus, the open-frame and modular FCI systems are designed to facilitate easy visual inspections and routine, on-site maintenance. By comparison, competitors’ enclosed-frame systems require complicated disassembly to allow shipboard inspection — a cost that can add up over the life of the marine RO unit.
Are marine desalination units noisy?

Some brands of watermakers are noisier than others, which is usually a result of inferior design efficiency and low-quality of components. Like any other piece of machinery, marine watermakers do make a sound when they operate. Some manufacturers don’t do anything to address this issue, and other manufacturers do things to “mask” the sounds, such as creating chambers or other mechanisms ostensibly designed to dampen noise resonating from system components.

FCI Watermakers has gone to extensive lengths to design and manufacture marine watermakers that are the quietest in the industry. We use only the highest quality motors, pumps and other components in our watermakers. Our systems are built on four-point vibration isolation mounts, which dissipate system vibrations and keep them from resonating through the vessel. All other components of FCI watermakers have been designed and selected to maximize noise control. The end result of this is that FCI watermakers are extremely quiet as compared to competing brands.

Can I make water with a marine reverse osmosis system while underway in a boat?

Yes, you can, but be careful to keep the through-hull, which is the intake for the marine water maker, well below the waterline. The reason for this is that the feed pump, or the low-pressure pump for the water maker, requires a flooded suction. If excessive air is introduced into the feed pump, the feed pump will lose its “prime” and the water maker will cease to function due to a lack of a feed water stream. In that case, the low-pressure pump would need to be “re-primed”, after which the water maker would function properly again. So if you intend to make water while underway, make sure that the intake through-hull is placed in such a position so that it does not take in air when the vessel is underway.

In what type of water will a marine reverse osmosis system work best?

Unlike some brands that test their watermakers under a certain set of criteria, FCI watermakers are designed to work effectively in a wide variety of sea water and brackish water conditions. The rated output capacities for FCI Watermakers systems are established at salinity range of 35,000 ppm TDS (total dissolved solids) and at 77 degrees Fahrenheit. These standards are representative of the salinity and temperature of average sea water. However, in different geographic locations, and at different times of year, both of these parameters will fluctuate.

As the TDS and/or the temperature vary from the standard ranges, it’s important to adjust the pressure regulator so that the water maker maintains its rated output. An example of this would be with brackish water, where the salinity might decrease to a range of approximately 3,000 TDS to 5,000 TDS. As a general rule, as the salinity decreases from the standard 35,000 TDS, system production will increase and the RO unit should be adjusted accordingly.

Likewise, as the temperature increases from the standard 77 degrees Fahrenheit, so does the output from the water maker. An example of this would be in tropical climates during summer months where water temperatures often exceed 77 degrees. In this case, the pressure regulator on the water maker would also need to be adjusted so that the water maker maintains its rated output.

What makes FCI Watermakers’ systems different from other reverse osmosis units available today?

FCI Watermakers has long been recognized in the marine industry for building reliable, durable, state-of-the-art watermakers. FCI has systems in the field with over 17,000 hours of operation on them still running strong.

FCI Watermakers offers the industry’s most comprehensive one year system warranty with a lifetime guarantee on reverse osmosis membrane vessels. Other watermaker manufacturers only offer a limited warranty with no guarantees.

We only use the finest quality components on our systems. FCI goes the extra step in building systems that provide customers with the most durable marine watermakers available in the marketplace. For example, FCI uses “washdown duty” motors on all marine systems. This means that FCI motors are epoxy coated and have neoprene gaskets. Other manufacturers typically use “general duty” motors, which are merely painted and their gasket material is made of cardboard. Plus, FCI uses motors with industrial-quality 316 stainless steel shafts. Other manufacturers use motors with steel shafts. Our high-grade materials enable our marine reverse osmosis systems to withstand the elements of wet marine environments and not succumb to corrosion and rust.

FCI Watermakers is the only manufacturer that offers the Universal Reverse Osmosis Controller (UROC) on a range of watermaking systems. The UROC controller offers user-friendly digital interface with full customizing, automatic operation for various applications and installations. UROC technology also provides users the ability to monitor and operate their marine watermaker from a computer. UROC controller technology is unique to FCI Watermakers, and is not offered by competing manufacturers.

All FCI watermakers come complete with a fully automatic fresh water flush as part of the system. Most other manufacturers sell them as accessories, which means additional costs to users. Fresh water flushes are an integral part of a watermaking system because they deter the build-up of biologicals in the watermaker when it is not in use. Manual flushes are not reliable because there is no guarantee that they are done on regular intervals by boat owners or their crews. With FCI systems, there are no extra buttons to push or valves to turn to enable the flush feature. When an FCI system completes its operation, it is automatically in fresh water flush mode. There is virtually nothing else like it in the marketplace.

FCI watermakers are economical to own, operate and maintain. The cost of acquisition of an FCI marine watermaker is very reasonable as compared to other RO units in the marketplace. And, operation and maintenance costs are negligible. Typically, all users need to do is replace filter cartridges and change the oil when warranted.

For more information on the high-performance features of FCI’s reverse osmosis systems, read the FCI Advantage.

Why would I want a marine reverse osmosis watermaker on a boat?

Safety is a paramount concern. If you have a marine water maker onboard, then you can avoid or greatly limit the potential risk to you and your passengers by providing virtually limitless fresh water in the event there is an emergency that keeps your vessel offshore for an extended period of time. This provides both you and your passengers with peace of mind.

There is also a tremendous risk in filling your fresh water tanks with dock-fill water, particularly in foreign countries where the quality of the water is uncertain. By introducing potentially contaminated water into your fresh water tanks you are exposing all people onboard to unknown risk. You know the water from your marine watermaker is fresh and will keep your tanks clean and safe.

Having the ability to make fresh water while you are underway frees your vessel from the burden of carrying the water weight necessary to accommodate an entire voyage. Water weighs approximately 8.3 pounds per gallon. This extra weight adds up and can reduce the distance you can travel over a given period of time. Also, if your vessel is power driven, your fuel costs will increase according to the additional weight you carry on your voyage.

Convenience is an important factor. No special stops are necessary to buy water as you voyage. Simply run your marine watermaker to fill your tanks and enjoy a limitless supply of water for longer showers, laundry, cooking, washing dishes, making ice and wash-downs with water that leaves your vessel spot-free.

All of these factors result in a marine watermaker being an extremely smart and economical investment for virtually every boat owner.

Commissioning Your Marine Watermaker for Long-Haul Cruising

To annually commission your FCI marine water maker and prepare for the “long haul,” you should first check through the entire installation on the boat.

1. Check the intake through-hull to make sure there are no obstructions.

2. Make sure the seacock on the intake through-hull functions properly (that it opens and closes correctly). This is often an overlooked issue. If the seacock is “frozen” in place, forcing movement can break it. Before the marine water maker is tested, make sure that the seacock is in the OPEN position.

3. Make sure all feed water (and brine discharge) hoses are free of leaks and that all hose clamps are secure.

4. Check the low pressure pump to ensure that the pump freely turns, that all electrical wiring is in good condition (no exposed wires, proper insulation, etc.), that the pump is properly fastened down, that there are no signs of leaks and that the low pressure pump seals are in good condition.

5. Clear and clean debris from the sea strainer. Make sure that the sea strainer gasket is not brittle (if so, replace it). When re-assembling the sea strainer, the basket should be properly seated so that air does not leak in through the sea strainer (a proper vacuum is necessary).

6. Renew/replace the prefilters on the marine water maker, and also make sure the seals on the prefilter housings are in good condition (again, they should not be brittle).

7. Renew/replace the fresh water flush GAC filter (this should be done every 3-6 months on average).

8. Test the fresh water flush line to make sure that the water from the fresh water tank reaches the water maker during the fresh water flush cycle. This assures that there were no valves that were inadvertently shut or that the line is somehow obstructed.

9. Check the high-pressure pump on the water maker for leaks. If found, you might have to replace the high-pressure pump seals and/or valves.

10. Be sure the high-pressure pump oil is fresh. Typically, high-pressure pump oil should be changed after the first 50 hours of system operation, and then after every 500 hours of usage.

11. Check the brine discharge through-hull to make sure that there are no obstructions.

12. Check the brine discharge seacock to make sure that it is functional AND that it is OPEN. (Many people forget to make sure that it is OPEN, which causes damage to the water maker if the water maker is operated with a “closed off” brine discharge line.)

13. Inspect the brine discharge hose to make sure that the hose is in good condition, that there are no leaks, and that the clamps are tight. (Also, there should be two hose clamps on the ends of each hose.)

14. Now test the operation of the water maker. It is best to test the water maker in open ocean conditions where the seawater is exposed to good tidal exchange.

15. Back the pressure regulator “off” all the way (turning it counter-clockwise as far as it will go).

16. Start the low-pressure pump (only) on the system and let seawater circulate through the system for about 15 to 20 minutes.

17. During this time, visually inspect the system, all components and all hoses to make sure that there are no leaks or other abnormalities. Confirm the feedwater inlet pressure is in the approximate range of 30 to 40 psi (depending upon the particular installation).

18. After this period of time, gradually increase the system pressure (turning the pressure regulator clockwise) until the system is making its rated product water output. Confirm the system operating pressure, feedwater TDS, and system output.

19. If the system comfortably makes its rated product water output, there is no further testing to do on the water maker. If the system is unable to make its rated output, then the user should call a service technician to conduct further testing on the membranes.

20. Once the system testing is complete, turn the system “off” and wait 10 seconds to hear the system fresh water flush solenoid activate. The user will hear the fresh water flushing through the system. Once the fresh water flush is complete, the water maker is ready to use for the season.

If you’re planning some long-haul cruising, important spare parts to carry on board include prefilters, high-pressure pump oil, GAC filters, high and low-pressure pump seals and high-pressure pump valves. It is recommended to replace seals after every 1500 hours of use and valves after every 3000 hours of use.

How To Choose A Marine Water Maker

 Many manufactures guarantee the performance of their marine desalinators, but there are several upfront indicators that signal their claims may not hold water. Here’s what to look for as you shop for a dependable marine water maker.

• open frame
• high-grade materials
• nonproprietary parts
• low RPM components
• necessary parts and features are included
• customized operation
• automatic alerts and data
• solid warranty coverage

Your first clue will be how the marine water maker system is packaged. Open-framed systems are designed to facilitate visual inspections and routine, onsite maintenance. Systems that are entirely enclosed require complicated disassembly to allow shipboard inspection or trouble-shooting.

Equally important are whether high-grade materials are used. High-grade alloys like industrial-quality stainless steel and bronze should be used for all critical components. Plastic plumps, for example can compromise system operation and even jeopardize the vessel with flooding if the sub-waterline pump is inadvertently cracked or stepped on. Motors should be epoxy coated to help protect your system from corosion. What’s more, water makers that use commercially available parts mean less hassle and less cost for you, versus brands that feature proprietary parts such as membranes, pumps and fittings that are expensive and available only at select locations.

Your marine reverse osmosis system should be resilient to all water conditions that you encounter during your travels. One way to assure that the performance of your marine water maker isn’t compromised as it processes different degrees of salinity and particulate is by utilizing low RPM components. Pumps that turn at excessive RPMs (for instance, over 3000 RPMs) are so susceptible to feed water variances that they require special filtration (often a proprietary component). This results in more frequent filter changes and added cost of operation.

Determine if the price of the marine water maker is inclusive of parts and features necessary to achieve rated outputs and superior performance. Often, important components are priced as separate packages, accessories or upgrades. For example, fresh water flush is required feature for your marine water maker to perform properly, however, it is not always part of the base price. Likewise, your marine RO system should come calibrated and ready to run. You should not be required to purchase additional accessories or calibration solutions to complete the set up.

You should be able to customize your marine water maker so it can be installed, run, modified and monitored based on your minute-by-minute needs. For instance, if your fresh water flush is pre-programmed to run every seven days, this lack of flexibility may inhibit your need to flush more frequently or for a longer duration, as is necessary to keep biologicals from fouling system components when cruising in warmer climates. Or, if your plans take you away from the vessel, you should be able to set the system to run for a certain period of time or to make a specified number of gallons, and then shut itself off automatically so there is no delay in having fresh water at the ready when you return.

In partnership with customization is watersmart intelligence. A preferred system will present automatic audio and visual alerts, finger-tip data and an onscreen help menu. With today’s available technology, you should not settle for anything less than a marine reverse osmosis system that’s so easy and efficient you’ll think the entire water maker consists of just a few buttons on your control panel.

It’s important to review the warranty before you make your purchase. Some warranties are complicated and contradictory, with terms and conditions that apply to individual components. For example, a warranty may be voided if you do not purchase the manufacturer’s proprietary parts.

Other questions you should ask are how extensively the marine water maker has been tested. Under what conditions and criteria did the manufacturer rate their outputs? Can you operate the system remotely? How is the marine RO unit designed to control noise — a pet peeve of many boaters. Moreover, doing your research and comparing the engineering and features of competing brands will reveal important superiorities that will ultimately make the difference in your boating experience.

FCI Watermakers optimizes marine desalination equipment?

Over a decade ago, FCI Watermakers pioneered features and automation never before seen in a marine water maker. FCI’s exclusive Universal Reverse Osmosis Controller (UROC) technology set the standard in operating today’s marine desalinators by integrating one-touch commands, multiple station operation and remote system control and monitoring of your water production from a computer and remote locations. FCI Watermakers are among the most effective marine desalination systems providing automatic and customizable fresh water flushing. This feature is integral to every marine water purification system because it deters growth of biological contaminants when the system is not in use.

How does desalination equipment work?

A marine desalination system begins with a through-hull fitting, or skin fitting, where ocean water is initially drawn into the system. The raw sea water is then filtered through a sea strainer to approximately 50 microns; and, further filtered to five microns by being pumped through a pre-filter using a low pressure pump running at approximately 30 to 35 psi. The reverse osmosis process begins when the filtered sea water is pumped under high pressure (at approximately 800 to 850 psi depending upon the temperature and salinity of the sea water) through the system’s membrane vessels. The product water that successfully passes through the membranes is then routed to a salinity probe, which confirms the quality of the water produced. If the product water is acceptable, this purified water is transported to a fresh water holding tank. Unacceptable product water that does not pass the salinity test is discarded and diverted with the brine discharge.

For more information on this topic, check out our blog post Desalination: How It Works And Which System Is Right For You.

Sea water recovery through reverse osmosis

For marine water purification, sea water is driven under high pressure through a special membrane. The resulting “product water” is potable water with over 99% of the Total Dissolved Solids (TDS) removed. The product water is directed from the marine water maker to a fresh water holding tank. Permeate that does not successfully pass through the membrane is sometimes referred to as the “brine discharge,” and on vessels is diverted overboard.

What is reverse osmosis?

 The osmotic process involves the natural movement of a solution through a semi-permeable membrane without applying external pressure. The membrane allows the passage of solvent but not of solute. In reverse osmosis, high pressure is used to push the solution through a membrane, which traps the solute on one side making pure solvent obtainable from the other side.

For more information on this topic check out our blog post, Desalination: How It Works And Which System Is Right For You.

What is a marine water maker?

 A marine water maker is a desalination unit that converts sea water into fresh water using a reverse osmosis process that removes salt and other minerals, making it suitable for human consumption.

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