Water Makers

 ECH2OTec Watermakers

 
1.  FEATURES & BENEFITS SEE MORE
 
2.  THE DECISION - What kind of watermaker to get? SEE MORE
 
3.  SAMPLE PUMPS SEE MORE

4.  ARTICLES OF INTEREST



 
Power Survivor Watermakers  






FEATURES & BENEFITS
 
FEATURES

BENEFITS



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THE DECISION – What kind of watermaker to buy?
CONVENTIONAL or 'ENERGY RECOVERY'? 

SWEET WATER FROM SALTWATER - The technique to make drinkable or ‘sweet water’ from saltwater is simply to force, under high pressure (800 TO 900 psi), large quantities of water past a special membrane. By the process of reverse osmosis (RO), which is the same phenomenon that puts oxygen into our blood from our lungs, clear drinking water emerges on the other side of the membrane. 
MEMBRANE - The ability to make drinkable water from saltwater is solely due to the invention of that membrane. Its quality and how it is used is critical.
POWER – The most reliable way to make quantities of water is to use lots of power to generate volumes of water under pressure. All major desalination systems are based on such a design as are many smaller systems. The exception is the ‘energy recovery’ type systems – designed to use far less power – ideal for survival equipment which was the original intention – but challenged when put to heavy usage.
TWO TYPES OF WATERMAKER – FOR SMALLER DESALINATION SYSTEMS
  • Conventional systems, like ECHOTec, that use relatively big pumps and motors – requiring lots of power – similar to large desalination plants – weigh 100 to 150 lbs. (45 to 70 kg.)
  • ‘Energy Recovery’ systems - use smaller plastic pumps – derived from a survival device – systems weigh 25 to 75 lbs. (10 to 35 kg.)
‘ENERGY RECOVERY’ SYSTEMS RATE POORLY – The UK’s pre-eminent Yachting World’s ARC 2005 (not included in 2006) Survey included 14 models of watermakers representing 10 brands on 76 boats – all participated in the Trans Atlantic crossing and reported on the performance of their watermakers. All 4 brands of conventional systems ranked on top with an average rating of 8.86 out of 10. All 6 ‘energy recovery’ systems were the bottom 6 with an average score of 7.0. Included in the ‘energy recovery’ bottom ratings are the four most popular brands – a total of 52 units. Although popular their reliability, user friendliness and value for money do not rate nearly as well as conventional systems.
‘ENERGY RECOVERY’ SYSTEMS - The energy recovery concept of watermaker has gained popularity amongst the offshore sailing community for very practical reasons – but is there a flaw in the logic? The concept was first developed as a survival system. Rather than pushing large volumes of saltwater past a membrane it uses relatively small pumps that pulsate, like a hand bicycle pump, to build up the right pressure level - only achieved by reducing or stopping water flow. Not only is the flow of raw water reduced but the pumps only achieve the right pressure with a pulsating stroke resulting in jolts of pressure. The advantage is that these systems use less power. They certainly work but their engineering is premised on reaching towards the maximums of their tolerances which makes them more vulnerable to breakdown with heavy usage.
Although ECH2O Tec does offer a ‘power efficient’ model those units still require twice the power of the ‘energy recovery’ systems – the trade-off is reliability.
IRONY OF ‘ENERGY RECOVERY’ ON A BOAT – Unlike a house for which you must buy power from a public utility, a boat must be its own ‘utility’ – produce all its own power. A boat has two types of power: 1) GENERATED POWER from whichever generators or sources (engine alternator, generator, wind generator or solar panels) - plentiful when producing and 2) STORED POWER in the ships batteries. That stored power is a valuable commodity especially when the only amount available is the dwindling supply in a battery bank. But when the batteries are being charged by running engines, generators or perhaps solar panels there is usually surplus energy that is not accepted by the batteries’ regulator. That is free and wasted power. Why not tap that source of free power to make water?
No need to use precious battery power to make water! Save that battery power for the essentials.
MAKE WATER WHEN MAKING POWER with equipment that can easily do the job. The ECHOTec system is like many others that employ as much power as is necessary – so that pure water is manufactured with ease – not straining pumps or motors – and keeping the membrane in good condition by maintaining constant pressure (pulsating causes jolts of pressure) and the helpful scouring caused by the heavy flow of raw water. When the boat’s engine or generator are running there is power to spare – an ideal time to make water as there is plenty of power and it is all free.
BREAK-DOWN - Break-down or failures of desalination systems are the result of:
  •  PUMPS - Pumps are the weakest link - suffer from over-working – excess load for size of pump – challenged pumps are hot and/or noisy. Plastic pumps are not designed for 800 to 900 PSI.
  • PRESSURE - Inconsistent or fluctuating pressure, especially from pulsating pumps, reduces the life of the membrane
  • MOTORS – Big, cool and quiet solves all issues.
  • LEAKAGE – Fittings and connections must be suited to the high pressure requirements. Dripping or, worse, spraying salt water causes enough problems...... dangerous if near electrics.
  • CIRCUIT BOARDS – Electronic circuit boards - 'Black Boxes' - and their anciliary mechanisms designed to achieve 'automatic' controls are added complexity - additional vulnerability to failure. Making water is not much more difficult than filling your tanks with a hose: switch the water on, run it for a bit, taste it, then when it tastes OK switch the flow into the tank. The backflush is simpler: just a matter of switching a 'Y' diverter to re-direct tank water to flush/clean the membrane/filter. ECH2O Tec's YACHT SERIES watermakers do not incorporate any such automatic controls to handle those simple procedures. Sailors tend to be 'around' when making water. The process is too easily monitored and managed by a human .... afterall .... only filling a tank. The sounds of saltwater splashing overboard, a starved pump, overflowing tank or lack of product flow are always self evident. The electronic minding of circuit boards and their ancilliary 'automatic' devices are not necessary and, most importantly, not worth their increased risk of failure.
  • MEMBRANES - Clogging of membrane caused by low flow rate of water because: 1) water impurities become too dense and 2) missing the scrubbing action of high volume water flow. An ECHOTec membrane should last 5 to 7 years of heavy usage. A membrane on a ‘power recovery’ system might not have half that life and with much less usage.
  •  AIR – Only the ‘energy recovery’ systems suffer from build-up of bubbles causing air ‘shock absorbers’ in the chamber that prevent achieving proper pressure. Conventional systems all easily flush air bubbles right through.

The ECHOTec systems are engineered specifically to address all these issues – resulting in cool and quiet systems that simply ‘just work’.



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SAMPLE HIGH PRESSURE PUMPS

All ECH2OTec high pressure pumps are:
  • Made of 316Ti, a titanium stainless steel alloy
  • Triplex/three cylinder - plunger style  
  • Ceramic lined cylinders  
  • Low revolution

.... designed to run silently and always cool - known to be the most reliable on the market today. The following selection is a sample of our eleven different models - note the weight - these are substantial units:

 


DC - 12 Volt - Powered from Batteries

 

ECH2OTec 260-DML DC Pump and Motor - weighs 47 lbs. (21 kg.)



  Belt Driven Pump - Powered by Belt from Engine

 

ECH2OTec 500-BML Belt Drive Pump with electro Magnetic Clutch - weighs 24 lbs. (11 kg.)

 

AC - 115 or 230 Volt - Powered by Generator or Inverter

ECH2OTec 500-AML AC Pump and Motor - weighs 66 lbs. (30 kg.)

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Article from OCEAN NAVIGATOR - JULY/AUGUST 2007

WATERMAKER INSTALLATION AND MAINTENANCE
 
by Nigel Calder
 
 
Practical tips on using a watermaker on a voyaging boat
         
On our first boat, on which we cruised around the Caribbean for 15 years and raised our children, I installed a noisy fresh water pump under the saloon sole where it could be clearly heard all over the boat whenever it was running. We were effectively able to enforce water discipline. To this day, all members of the family never leave a faucet running!
       
We had other water conservation measures, which some guests found to be rather repulsive (notably using the dishwater until it was pretty disgusting and obliging anyone who took a shower to tromp up and down on the laundry.) We had the decks organized such that in a squall we could flush them and then divert the rainwater to the water tanks. We never came close to running out of water, but we had to engage in active water management.
         
The combination of a near-silent water pump and the watermaker on the last boat encouraged a certain degree of reckless water use. With the family, old habits die hard, but guests are another matter. They’ll wallow in the shower for extended periods, and run the faucet while brushing their teeth or washing a teacup. I find it hard to take (and to keep my mouth shut) but it’s really not a problem. It’s all part and parcel of cruising lifestyle that has changed dramatically over the past 20 years.
 

Installing a watermaker
         
Watermakers can be bought as an integrated unit mounted on a common base plate (a “compact” unit) or as component parts, which are mounted individually in the boat (a “modular” unit). There is generally little difference in the purchase price, although there will often be a significant difference in the installation cost because of the added work required by the modular units. The choice of which to use will be driven by the available spaces on the boat, bearing in mind:


Following installation, it is an excellent idea to log as much benchmark data on the performance of the unit as can be measured with the available instrumentation. This data will provide invaluable reference points for future monitoring and troubleshooting (in particular, giving early warning of filter and membrane fouling). It should include such things as:
  • The source water (sea water) temperature.
  • The feed water pressure (if there is a booster pump) upstream of the filters (on the inlet side of the main pump).
  • The operating pressure on the system (at the membrane housing).
  • The product water flow rate (if no gauge is available, this can be measured by diverting the flow to a bucket and timing how long it takes to collect a measured amount).
  • The salinity of the product water (if there is a salinity meter).
  • The brine flow rate (this can be measured by holding a bucket below the discharge through-hull and timing how long it takes to collect a measured amount).
  • The amp draw on a DC system.

Filter and membrane care are the two principal maintenance issues with watermakers. In addition, most high-pressure pumps, have an oil-filled sump that needs checking from time to time.
 

Filter maintenance
           
The addition of some kind of monitoring device (such as a pressure gauge on the suction side of the main pump) that will warn when filters start to plug is recommended; more sophisticated watermakers also have an automatic shut-down circuit that will not allow the watermaker to be run with plugged filters.
         
Raw water strainers are cleaned as with an engine raw water strainer – most have a removable basket that is washed out with seawater.
         
Additional filtration generally consists of some kind of removable pleated filter. These can often be cleaned by careful flushing of the filter surface. Each time it is hosed off will yield approximately an additional 50-percent life expectancy (e.g., if the new filter runs 100 hours, and after the second another 25 hours, etc.). At the first sign of damage, the filter must be discarded (some manufacturers recommend to clean no more than once and then discard).
 
Membrane maintenance 
         
Depending on how the watermaker is used, membrane care can be the major part of the needed maintenance. The extent of the work involved varies markedly from unit to unit, principally as a function of the quality of the source water filtration, regularity of use, whether or not there is an automatic flushing circuit, and the extent to which membrane maintenance is rendered unnecessary by a Z-Guard or Z-Brane unit.
 

Flushing a membrane
         
As noted previously, if a membrane is left unused for more than a week, it will be susceptible to bacterial fouling. The best way to minimize watermaker maintenance is to use it often: in other words, do not fill the tanks and then shut the watermaker down for two weeks; instead, top off the tanks at least every three days. If the unit is to be left unused for more than a week without Z-Brane protection, it either needs to be put into storage mode or else flushed with fresh water at least once a week.
         
Note that long distance passage-makers confronted with an approaching storm may find it advantageous to top off the tanks before the storm hits. This way there will be plenty of water on board, and the system will not need to be run, flushed or maintained in any way for several days.
         
Typically, the water used for flushing (somewhere between five and seven gallons) is drawn from the boat’s water tanks. However, traces of chlorine will do permanent damage to membranes. For this reason, some installations include a separate tank into which product water is diverted and held for flushing purposes, while others include an activated charcoal filter between the water tanks and the flushing circuit. The charcoal filter removes any trace of chlorine. Note that once wetted, charcoal filters only last about six months.
         
Bare-bones systems have to be flushed manually, which is one by switching to a couple of valves on the inlet and discharge sides of the watermaker and then turning it on. Sophisticated systems have automatic flushing controls powering solenoid-operated valves. The flush interval can be set by the user. This enables a watermaker to be left idle for some time without the need to pickle the membrane (so long as the unit does not run out of flushing water).
         
On some units, the flushing water also passes through the feed pump, while on others it does not, which leaves salt water standing in the pump. If the pump is made of plastic (e.g. the Shurflo pump used by Spectra and others) this is not a problem, but if it is made of stainless steel it may lead to corrosion.
 

Pickling a membrane
         
Special biocides are used for pickling a membrane. These are mixed with product water and then pumped through the system, leaving the membrane cylinder full of the biocide solution. When it comes time to put the unit back in service, the biocide is flushed out by running the unit in an unpressurized state (to achieve maximum flow through it, with no product water production) for some time (generally 15 to 20 minutes) before restoring pressure and production. The initial product water will still be high in dissolved solids, and so must be discharged overboard via a bypass line (this is the case any time a watermaker is first stared). On cheaper units, this is done manually; on more sophisticated units, a salinity meter controls an automated bypass circuit.
           
Note that some watermakers (notably Spectra) include parts that will be degraded by some pickling agents. It is essential to use only the pickling agent recommended by the manufacturer.
         
Winterizing takes the form of pickling the membrane (it must never be left dry), draining the filter and the rest of the plumbing (filters should not be left wet) and, in some cases, adding potable antifreeze (propylene glycol, such as sold for winterizing RVs and caravans) to the high-pressure pump (the low-energy pumps, in particular, can trap water that is hard to drain out; this can crack the pump in a hard freeze). Spectra also recommends pickling the membrane with propylene glycol, and in fact suggests this for pickling in general, because “this seems to do less damage to the membranes than other storage compounds”.
         
In general, it is best to backflush the system every week, if this can be done, rather than pickle it during a relatively short-term lay-up.
 

Cleaning a membrane
         
Over time, a membrane will inevitably become fouled. A watermaker will exhibit higher than normal pressures and lower than normal product water flow rates. However, before assuming the membrane is to blame, check the feed salinity, feed temperature, operating pressures and filters. Also, check the operating voltage (DC or AC) at the pump under load. DC systems, in particular, will be significantly affected by low voltage.
         
Membranes need cleaning on average once every two years (membrane life on average, is five years). There are two types of membrane cleaner – alkali and acid. The alkali is most effective on biofouling and is generally used first (some firms recommend using the acid first). The acid is effective on mineral fouling (e.g., calcium), but is generally only used if the alkali fails to restore product water flow rates.
         
To clean a membrane, it is first flushed with clean water and then the alkali solution is mixed with the clean water in a bucket (preferably hot water to improve the performance of cleaning agents). The unit is run for an hour or so to circulate the solution through the membrane, then allowed to rest for an hour or so, and run again for 15 minutes or so.
         
After this, the system is put back into service, unpressurized and run for 15 minutes or so to clear out the cleaning solution before being returned to regular service. Once again, the initial product water will need to be discharged overboard, either manually or automatically.
        
If performance is still poor, the same procedure is repeated with the acid cleaning solution. Cleaning membranes is hard on them and something of a crapshoot. It should only be done when other measures do not restore output or operating pressures.
 
 
Pump maintenance 
         
When operated with properly filtered source water, traditional watermaker high-pressure pumps will need the valves and seals replaced approximately every 2,000 hours of use. The manufacturers provide rebuild kits and instructions. Booster pumps and the feed pumps on the low-energy systems will also need an overhaul at similar intervals of use. Additionally, those pumps that have an oil-filled crankcase need an oil change every 500 hours.
 
 
Watermaker drive options
         
Almost all large-capacity watermakers require an AC power source (i.e., an onboard AC generator). For lower capacities, AC, DC and engine driven units can all be used.

AC watermakers: On a boat with a continuously operating AC generator, a relatively small AC watermaker can run long enough hours to meet the overall load on the generator demand This helps to keep the overall load on the generator down, minimizing the size of generator needed, and the size and weight of the watermaker. When a generator is only run intermittently, the watermaker needs to have the capacity to meet the demand in the restricted running hours. This may result in a large watermaker that then requires a larger generator to run it. Longer generator running hours may have to be accepted in order to downsize the watermaker and generator. Alternatively, it may be possible to employ load-sharing technology to run a larger watermaker from a relatively small generator by managing the other AC loads on board.

DC watermakers: DC watermakers are run off the batteries. Typically, the demands of the watermaker are low enough, and the capacity of the battery bank large enough, to be able to run a relatively small watermaker long enough hours to meet the boat’s needs. The batteries are then recharged during normal charging periods. (Note that most DC watermakers will have somewhat higher output when batteries are being charged because of the higher voltage on the DC system: it often pays to include battery charging periods in the watermaker run time). The net result is a relatively small and lightweight installation that can meet a substantial water need. The precondition is a DC system that has capacity to handle the demands of the watermaker.

Engine-driven watermakers: Although watermaker pumps can be driven off a boat’s main propulsion engine, this is not generally recommended. The variable engine speeds when the boat is underway may cause problems, and in any case most times you don’t want to have to run the main engine at anchor to make water. If the boat has an AC or DC generator (both of which typically run at fairly constant speeds), it may be possible to configure the system to directly drive the watermaker pump. However, it generally makes just as much sense, and is a more versatile installation, to use an AC- or DC-powered watermaker. In any event, if an engine-driven watermaker is used, it needs to be sized to provide the necessary output during normal engine-running hours.
 
 
 
Electrostatic protection?
         
The Zeta Guard (Z-Guard) Protection System from Spectra consists of a filter housing containing an electrode that generates a powerful electrostatic field. It is placed in series with the raw water supply to a watermaker (or any other device using raw water). The theory is that the Z-Guard puts a positive charge on any particles (mineral or bacterial) in the source water. This positive charge is said to keep the particles from binding together, and from sticking to surfaces in the system, including the membrane. In this way, biofouling and scale formation is minimized.
         
Spectra claims that a Z-Guard (or Z-Brane, an adaptation of the Z-Guard specifically designed for membrane protection) eliminates the need for pickling watermakers when they are not in use, but others in the industry believe that the effect of the electrostatic field is short lived, after which the water reverts to its natural state, rendering the system ineffective. The Z-Guard and Z-Brane units run on 12 volts, pulling 150 mA (3.6 Ah over 24 hours).
 

A mid-Atlantic problem
         
On our recent trans-Atlantic passage (High pressure makes for a smooth passage,” Nov./Dec. 2006, Issue No. 158), the hose from the feed pump to our watermaker split at the hose nipple (as a result of a combination of using the wrong hose, and then not securing it adequately, which allowed the hose to flex under pressure from the feed pump). Salt water sprayed all over the engine room, including the fresh water pump, which destroyed the high-pressure shut-down circuit on the pump. The fresh water pump went into full continuous operation, drove the pressure on the fresh water system above the setting for the pressure relief valve on the hot water tank, and dumped all the fresh water from the tank in service into the bilges.
         
Unfortunately, we had previously drained the other water tank dry, so now, mid-Atlantic we had no fresh water on the boat. We were able to re-supply from the watermaker, but had this failed we would have had a problem we would never have had on our previous boats precisely because we had a watermaker on board!
         
I learned a couple of lessons from this. The first is to never run one water tank dry before switching to the next, but rather to run one down half way and then switch, and to then refill from the watermaker once the second is half empty. This way, there will always be an emergency supply of fresh water on board. The second is that even with a watermaker, it’s important to keep track of water usage. Our next boat will have some kind of an alarm that goes off if the fresh water pump runs for more than a certain length of time.
 

Troubleshooting a watermaker
 
Properly installed and run, watermakers are pretty reliable and trouble-free. The following are some of the more common problems:

  • System will not start: The problem is probably electrical. Check for voltage at the motor. If not present, check all fuses and breakers, and any shutdown circuits (the unit may have shut down because of high or low pressure). If there is a voltage at the motor, check the motor itself.
  • System starts but shuts down after a while: The high- or low-pressure protection devices are sensing plugged filters or abnormally high operating pressures.
  • Pump is operating but there is no product water: Check the high-pressure gauge to ensure that the system is operating at the required pressure. Make sure the suction side through-hull is open, all valves are in the correct position (you may be sucking from a flushing intake or discharging the product water overboard), and the pressure relief valve is not open.
  • Reduced product water: A traditional watermaker operating in cold water will experience a substantial drop in its product water output. Otherwise, suspect a fouled membrane (the membrane housing pressure will be unusually high on a low-energy system, but may not be on a traditional unit; the amp draw will be high on the low-energy system); on a low-energy system plugged filters may also cause a reduce output (check the inlet pressure/vacuum to the main pump to see if it is low), as will low voltage at the pump when operating. There may be leaks in the high-pressure hoses. If none of these are the case, the high-pressure pump cylinders may be leaking past the pistons. In all such cases, the amp draw on a low-energy system will be lower than normal.
  • Normal water production but with high pressure: The seawater is colder than normal and/or the membrane is fouled.
  • Normal water production but with low pressure: The seawater is warmer than normal or the salinity is lower than normal.
  • Water production is high but poor quality: There is a membrane failure or an O-ring failure in the membrane housing.
  • Low-energy watermaker exhibits uneven pressure and flow readings: One of the seals in the shuttle valve, on the piston rod or in the cylinders, is leaking by, or one of the cylinders is scored and leaking by.
  • Low-energy pump locks up: The shuttle valve is broken. The pump may, in fact, run when unpressurized, but lock up under pressure. On some of the earlier Spectra models it can be repaired by drilling a hole through the shuttle valve and screwing the pieces back together!


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Article from BLUE WATER SAILING – June 2007 issue

TECH REPORT 
 
Choose Wisely a Watermaker
 
One cruiser’s research points to the benefits of a 110-volt system
by Sam Mazza
 
So you are in the market for a watermaker. You are willing, finally, to plop down a few grand so that you won’t have to do a rain dance every time you want to take a shower. If your battery-recharging regiment includes using a diesel generator, this article may be for you.
 
You are ready to make a big decision so you are doing full scale market research. You have discovered that there are many choices. Maybe even more than you care to study. You have checked the specifications of various models from a few manufacturers on the web, read articles in magazines, talked to other cruisers, gone to a boat show to speak to a manufacturer’s representative’s, collected brochures, what the heck, you may even have a spreadsheet with all the information that you have gathered. But, in the end, how do you actually choose? Wisely, that is. Which of the many criteria are deal makers and which are deal breakers? Look at all of the parameters you have to evaluate (in no particular order): cost (initial plus consumables), reliability, guarantee, amp draw, output per hour, output per amp, cost of operation per gallon, available space for installation, noise, ease of use, ease of maintenance, availability of spare parts around the world.
 
Certainly you don’t need my help in figuring out which watermaker you can afford and which you can’t. Most technical information that you can use to compare watermakers is readily available. In spite of all the information, a clear winner might not be so obvious. Well, this is where I can help a bit to narrow the choices. But don’t expect the end of this article to name a brand and model. There simply is no one-size-fits-all magic formula when it comes to selecting a watermaker.
 
There is at least one criterion I left out intentionally from the list above. Can you spot the missing one? While you are thinking about it, I want to touch on some criteria from the list above.
 
CAMPING OUT IN STYLE      
 
Apart from the specifications, what else is important in selecting a watermaker? When I left the U.S. on my sailboat a fellow cruiser told me that cruising is like camping on the water. Well in a sense it is, but only to the extent that you make it so. Being a cruiser already requires quite a few lifestyle compromises and sacrifices. So why add more? Why can’t we cruisers camp out in style? After all it is our lives we are talking about. Personally, I did not want to give up my shower regiment. Back home I would shower at least twice a day. And since I started cruising I learned to take two showers a day without going water-broke. And I can still afford a quick freshwater rinse after a dip in the big blue. In all, I might consume about eight gallons per day (GPD). With a medium-sized watermaker, we are talking about one hour of operation and probably no more than 20 amps. If you are cruising as a couple, you can probably live comfortably on about 15 GPD. A crew of four might need 30 GPD, maybe a bit less with some extra discipline.
 
Why is all of this important, and how does it affect your usage of the watermaker? You need to establish a base for how much water and amps you will need to generate for each live-abroad day. Than you will have to figure out how to get back what you have spent. I choose to run my watermaker everyday to replenish yesterday’s consumption. It is part of my daily routine: take two showers, brush my teeth after every meal and refill the water tanks. My reasoning is that when something unexpected happens that might disable the watermaker, I will have only one day’s worth of water deficit. Then I can start making additional sacrifices and conserve water like I’m camping in the Mojave desert. If I had run the watermaker say once a week, I would be out 56 gallons. That is a tad over half of my 100-gallon total capacity. And that would not be a position to envy. I can then figure out what capacity watermaker I need. If I am OK with running the watermaker two hours per day, then a four-gallon-per-hour (GPH) watermaker would do just fine. But if my patience is just for one hour of water making, then an eight-GPH system would do better. But as a general rule, I would never buy a system that would have to run at its full capacity to satisfy my needs. So if I had to choose a new watermaker for my boat I would be looking to get at least a 10- to 12-GPH-producing system. The extra capacity acts as a safety buffer.
 
Hopefully I have convinced you that running your watermaker is a good idea. Now you can figure out your daily water-making amp cost. It follows that you must have some way of recouping those precious amps. Depending on your electric system, you could be doing so using solar panels, wind and/or a diesel generator. If you have sufficient wind and solar generation capacity, you will have no further problems. Let the watermaker make water. Let nature recharge your batteries. But if you are planning to recharge your batteries with a generator, I want you to pay close attention, just about now-this is where “wisely” comes into play.
 
RECHARGING ROUTINE
 
The criterion I had omitted earlier in the article was your recharging routine. Suddenly wisely choosing a watermaker involves an understanding of your electrical recharging system. Let us review some battery charging basics.
 
1)     For every amp that you draw from your batteries, your generator will have to produce about 1.2 recharging amps. That is so because there is a loss in the recharging process. The actual extra amount depends on the health and state of your batteries, but a 20-percent margin is a reasonable assumption.
2)     The type, health and state of your batteries will also determine how many amps can be absorbed per unit of time. The fuller the batteries, the fewer the amps they can absorb. During a normal charging cycle, fewer and fewer amps are absorbed by the batteries. With my Westerbeke 7.6-kilowatt generator, I can push 80 amps at the beginning of the charging cycle. But that declines until it no longer becomes efficient to run the generator because so few of the amps produced are absorbed by the batteries. At that point I am just burning fuel. Typically, I shut the generator when the batteries are absorbing no more than 10 to 15 percent of their capacity.
 
It follows that during a full charging cycle your generator will be able to output more amps than your batteries can absorb. You might want to read that sentence again; it is key to this article.
 
Let us look at an example, say you consumed 20 amps and your generator is putting out 60 amps and you batteries are able to accept 60 amps per hour. It would take 24 minutes (20 plus 20 percent of 20) to recover those 20 amps. How does this scenario look if the batteries can only absorb 40 of the 60 amps per hour that the generator makes? Twenty four amps is a bit more than a half of the 40 amps that can be absorbed. So you will have to run the generator for more than half an hour to recover the 24 amps. Furthermore, the spare 20 amps that the generator is putting out are, well, lost.
 
LESS WASTE
 
The beauty is that there is something you can do to avoid some of that loss. That is when a 110-volt, rather than a 12-volt, watermaker comes to the rescue. With a 110-volt watermaker, your daily routine draws 20 amps less from the batteries. And when you run the generator to recharge the batteries you will be using what would have been your daily wasted generator output to make water. Got it? In other words, you are going to be running the generator anyway. Your generator outputs more amps than can be absorbed by the batteries. These amps can be used by the 110-volt watermaker. Certainly this argument doesn’t apply only to watermakers.
 
Maybe you are not yet convinced. Let me ask you one last question: What do watermakers and generators have in common? Answer: They both make noise. I, as part of my daily routine, run my 12-volt watermaker at the same time that I run my generator. I might as well make all the unpleasant noise I need to make in the space of as little time as possible. I would rather hear the waves and the wind than the hum and buzz of the generator and water pumps. Basically, I am, by choice, already running both systems at the same time, even though I have a 12-volt watermaker. With a 110-volt watermaker, I wouldn’t have to worry about charging inefficiencies, and there would be one fewer system taxing my batteries.
 
Finally, I think it would be a safe guess to say that you would run neither the generator nor the watermaker unattended. So if you do not run them simultaneously, you would be confining yourself to your boat for the duration of running both systems successively. You could be sitting at a seaside bar having a cold one instead.
 
On Yanti Parazi I have a Spectra 380C watermaker. It is a 12-volt setup with two Shurflo feed pumps, with about 15 GPH capacity. These pumps are the weak link in an otherwise great system. Eventually I gave up on repairing and replacing these pumps and started to look for alternatives. That is when I realized that I would be better off with a 110-volt pump. I am now searching for a suitable alternative. It turns out that there isn’t a prefect pump that would fit the 380C system specifications. But that should not hold you back from buying a 110-volt system from the get-go. It is easier to buy a 110-volt system than to upgrade one.
 
Any which way I look at it, it makes more sense to have a 110-volt watermaker than a 12-volt one. Until I find a replacement pump, I will compromise and live with what came with the boat. But you have the advantage of learning from other’s not-so-wise decisions. Whatever watermaker system you decide on, make sure it will meet your needs. And remember that you can’t go wrong if you never say never and always choose wisely.
 



....the response from Spectra's President in the August issue of Bluewater Sailing magazine - 'Letters to the Editor'

Watermaker solutions for cruisers

 
Thanks for giving me an opportunity to comment on Sam Mazza’s article “Choose wisely a watermaker” that was in the June issue.
 
I feel that Mr. Mazza’s analysis is misleading, and from our perspective needs clarification. If the fundamental question is should I choose an AC watermaker or low-voltage DC watermaker, then you should look at the pros and cons. To make a valid comparison, let’s assume that we are evaluating an AC watermaker of a conventional type with a 120-volt or 240-volt AC induction motor. We can compare this to a 400-gallon-a-day Spectra or other brand with an energy efficient pump.
 
First let’s look at the power consumption of a 120-volt watermaker. A standard 400 GPD AC watermaker requires minimum of 2,000 watts to operate. A comparable DC watermaker will require 325 watts to operate. The AC machine will require a generator that is capable of starting a large induction motor with a rating of at least three times the run load or at least a five to six kilowatt generator. This may be fine if you need the generator for other purposes, but on a medium-sized vessel one needs to consider the weight, expense and maintenance of a generator set of that size.
 
The other issue is if your generator were to fail then you have no fallback for water making. A DC machine however, can operate off the batteries, main engine or be supplemented by solar and or wind power. Most cruisers make water when they are motoring as their alternator provides more than enough energy to operate a DC machine. This way there are times that you could cruise for weeks without having to use the generator at all.
 
The difference in the energy requirement between an AC machine and a DC machine is efficiency so you need to figure that with an AC machine you are wasting between 1,700 and 2,000 watts an hour. This is energy you are paying for in the form of fuel and generator maintenance expense.
 
Another major point is that we recommend running a watermaker every few days or once a week to make a larger quantity of water and then giving the machine a fresh water flush. This reduces the water required to flush the machine to a small percentage of the overall total making the most of your watermaker run time.
 
Finally, Mr. Mazza seems happy with his Spectra watermaker with the exception of maintenance required by the special Shurflo pumps. It is true, this is a weak link of the system and periodic overhaul of the pump heads is required. We have recently managed to reduce the costs of the repair kits to make this task less onerous for our customers. However, the weak link in any watermaker is the pump and conventional AC systems have a very expensive pump to overhaul.
 
Bill Edinger
President
Spectra Watermakers, Inc.




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