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Clean Drinking water Part 1
Marine & Boat Watemakers
Creating clean drinking water on your boat and while cruising is a necessity. Water tanks can only hold so much water and restricted space onboard may preclude you from carrying enough water for your needs. Whether you have enough capacity for all your water needs or not, having a marine watermaker can make planning a long distance cruise easier.
Wouldn't it be great if you could add more drinking water to your tanks at the flip of a switch. Well you can but there are many things you should know about marine watemakers. They are complex in installation and maintenance. However if you learn the basics you can easily keep your watermaker producing your water requirements.
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Installation diagram of a modular boat watermaker Size of watermaker for your needs Operation Considerations for marine watermakers Watermaker maintenance procedures
How do marine watermakers work
Watermakers use Reverse Osmosis to make water. This is the opposite process of osmosis that plants use. Wiki definition of Reverse Osmosis and description below;
Reverse osmosis (RO) is a separation process that uses pressure to force a solvent through a membrane that retains the solute on one side and allows the pure solvent to pass to the other side.
The membranes used for reverse osmosis have a dense barrier layer in the polymer matrix where most separation occurs. In most cases the membrane is designed to allow only water to pass through this dense layer while preventing the passage of solutes (such as salt ions).
This process requires that a high pressure be exerted on the high concentration side of the membrane, usually 2 to17 bar 30 to 250 psi, for fresh and brackish water, and 40 to 70 bar 600 to 1000 psi, for seawater, which has around 24 bar 350 psi, natural osmotic pressure which must be overcome.
Although Reverse Osmosis seems like a complex system it is really a simple and straightforward water filtration process. High-pressure (pump driven) reverse osmosis systems have been used for years to desalinate water to convert brackish or sea water to drinking water Types of boat watermaker There are watermakers for boats, watermaker for yachts, watermakers for sailboats and for any size boat. They come in modular setups, Self Contained or Portable and handheld units. Self Contained  Most
manufactures produce self contained units that house all the parts of the
watermaker between the thru hull and the water tanks. These setups are
easily controlled but require a large amount of space. This is
SK watermaker SC unit which has
sizes 8 to 10 GPH up to 83 to 85 GPH.Modular systems   Modular
systems can be mounted in individual parts and do not require one large
spacebut several much smaller spaces. The images of the Spectra Catalina 300 watermaker installation are thanks to MadDogVoyager. MadDog are one of those boat owners who like to share what they do and have onboard. Notice the membrane is fitted vertically inside a hanging locker while the pumps and filters are underneath a v berth. Portable and handheld  Katadyn
Power SurvivorKatadyn Swiss portable
watermakers, this one is recommended for
liferafts. Also look at their low power consumption and 12V power
watermakers.
Spectra Newport watermaker Schematic
1;
Thru hull
Components for a typical Marine Watermaker A typical marine watermaker installation involves a seawater supply, preliminary filtration to remove weeds and large contaminants, a low pressure pump to push the water through the particle filter which remove particles down to 5 microns, a high pressure pump to supply the RO membrane. Fresh water from the membrane is then sent to the water tank. For every gallon of fresh water produced roughly 10 gallons is required to pass through the membrane, the remainder goes overboard in the form of brine. Hose runs should be minimal especially in low energy systems.
Other features include, Automatic pressure adjustment which allows for variation in salinity and temperature of the sea water. Power Supply Power to the pumps, is supplied by battery, generator or engine driven pumps. Large capacity watermakers generally need an AC power source. Smaller capacity and low energy watermakers can use DC AC or engine driven pumps. AC It takes energy to pump water at high pressure. Most of the power consumed in an RO system is used to power the high-pressure pump. Large-capacity systems are typically powered with 120- or 220-volt-AC motors and can require generators capable of delivering at least 3 to 4 kilowatts (to handle the motor starting load). On a boat with a genset which is run often or continuously a relatively small watermaker can produce the required water. If the genset is run only occasionally a larger capacity watermaker is needed. DC Smaller low energy systems can be driven with 12- or 24-volt-DC motors, making them more suitable for typical cruising boats. Selecting the optimum system requires consideration of the vessel's power capability and the number of hours per day the system will have to be operated to provide the desired quantity of water. Running the DC watermaker at the same time as the batteries are being charged will help output of the watermaker. Make sure when you are researching a DC watermaker that the DC system on your boat can handle the loads. Battery capacity may need to be increased Engine driven pumps It's possible to power an RO system's high-pressure pump directly from the propulsion or genset engine, bypassing the need for electricity; however, this type of installation will require custom engineering. Size Matters How much water are you going to need, what size watermaker do you need? 1 Calculate how much water you need by estimating your daily usage/person/day. Older estimates allowed for a minimum of 1/2 to 1 gallon/person/day. This rate does not include showers, dishes and other extras. Nowadays with modern conveniences its more like 2 1/2 to 3 galls/person/day. 2 Work out how much you want to run the watermaker. You don't want to run it all day, but you may want to run it while the generator is on, while the engine is on and your charging your batteries. So maybe 2-3 hour per day run time is reasonable. 3 Tank size is also an issue. Its no good making 400 gallons if the tanks are not big enough. Normally watermakers give their estimated outputs based on 70 degree F. Colder water temps may produce less water.
Making water is not a luxury it is a necessity so its no wonder there are so many purveyors of equipment.
In the US popular models are Village and Spectra while PUR now Katadyn are popular handhelds. spectra and other companies can be seen at most boats shows. heavy boat show schedule popular in small boats
Aquamarine Washington State
Dessalator Italy
ECHOtec Trinidad
Filtration concepts California
Horizon Reverse Osmosis California
Katadyn Swiss
Matrix Utilities Florida
Offshore marine California & Florida
Quality Water Works North Carolina
SeaRecovery California
Selmar Italy
Schenker Italy
SK watermakers Florida
Spectra Watermakers California PowerPoint demo Newport range
Village marine California
Watermakers inc Florida
waterlog UK
They had many spare parts but still the watermaker failed. They even had backup PUR hand pumps and for a week of sailing that's all the water they had. They eventually had to plan a pit stop to get more spare parts and the nearest point of land was Ushuaia Argentina the most southern city in the world. they had their shore crew meet them with more spare parts and they were quickly back in business and on their way. It was an important lesson in having enough spare parts but most importantly the fact they had hand pump backups as this fact saved their lives as they were over 1,000 miles from land when the issue surfaced.
This picture is of New Zealand Atlantic rowers who used the Katadyn Power Survivor as their water supply plus backup air guitar.
Maintenance
First check your manufacturers maintenance requirements. The diagram above shows the parts in the system, All these need to be checked but the filters in particular are most important. Clogged filters and a dirty membrane will make for poor and low production.
Filters
Regularly check the sea water strainer and the two particle filters
Membrane
Watermakers like to run often even daily for a couple of hours. Running the watermaker like this coupled with automatic back flush, which takes the minerals salt etc off the membrane surface, keeps the membrane clean and in good working order.
A membrane not cleaned in a week can get bacterial fouling. If you do not use the watermaker in a week you should flush the system or put it into storage mode which involves pickling. Membranes should not be stored dry.
Membrane Flushing
Some systems have an automatic flush system built in, other smaller units require manual flushing. Some systems may have a separate tank for water for flushing.
Manual flushing of the membrane requires switching the valves on either side of the membrane, the inlet side and the discharge side, and then turning the unit on to circulate clean water.
Many larger systems have an auto flush mode. This can save lots of time and convenience.
Flushing water needs to be free of chlorine and so a carbon filter is recommended between the tank containing the flushing water and the membrane. Chlorine can react with some cleaning chemicals. Membrane PicklingThe membranes should be permanently immersed in liquid: either sea water before treatment, fresh water provisionally stored or sterilizing liquid if the water maker is not used for extended periods of time Pickling involves special biocides which are mixed with the product water and pumped into the system leaving the membrane saturated. Use the manufacturers recommended biocide. Spectra Z-brane note, Spectras Z-brane which claims to reduce the need for picking of the membrane. It may be sensible not to totally rely on this. Z-brane will reduce the number of times you will need to pickle the system but probably best to pickle the system if the watermaker is not used for extended periods.TemperatureThe membranes should not be exposed to temperatures freezing. Overpressure due to expansion caused by freezing can rupture the membranes and prevent the salt from being filtered out. The membranes must not be exposed to temperatures above 60°C as high temperatures may also prevent salt from being removed. Brackish waterWatermakers are not recommended for use in muddy or polluted water as the pre filters get clogged and damage the membranes. If you do use the watermaker in these waters only run it for very short periods: as soon as clean sea water becomes available clean the membranes and run the system without pressure for 30 minutes with the pressure regulator open. Spare parts
Carry plenty of spare filters. Filters last 6 months after first use. Also carry spare parts for pumps etc especially if you are going to be away from land or good stores.
You have fresh water, what no, what do you mean no. Water from the membrane goes into the water tank however there maybe contaminants in the system for your newly fresh water.
If you want to build your own watermaker you can read this report where the builder paid around $2,000 instead of closer to $8,000 for a bought one.
Read part 2 of the making fresh water series to find out how to keep water fresh and soft.
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