Motor Yacht Watermakers

DC versus AC

There was a time when the typical cruising motor yacht would have to run its generator practically all day to have functional systems. On large yachts this is still the case. Fortunately today there are other options to the noise and additional equipment wear and tear.

With the introduction of large, highly efficient inverter/chargers, high output alternators with smart regulators, and efficient batteries it is possible to greatly reduce generator run time. A limiting factor has often been the AC watermaker. Drawing too much power to run on an inverter, the AC watermakers production is limited to the generator run time. As a result, very expensive, high capacity units are typically used to make enough water in that limited time. The popular DC watermakers were too small and inefficient to be practical. Until recently there really wasn’t any other option available.

Fortunately, there is another option:  Spectra Watermachines

The Spectra Watermachine with its low pressure high efficiency feed pump system combined with Spectra’s MPC 5000 remote control panel giving one button operation, automatic salinity control, automatic fresh water flush, pre-filter condition indication, and general self diagnostics, Spectra can provide several compact, automatic packages ideal for power boat applications.  Utilizing our patented, super efficient, Clark Pump, high pressure system, an AC generator is simply not needed. The Catalina 300 can produce about 14 gallons per hour on 15 amps 12 Volts DC at rated temperatures. That is right, about 1 gallon per amp hour!  The Newport 400 can produce 17 gallons an hour (gph) on less than 24 amps 12 VDC.

A well equipped motor yacht should be able to limit generator run time to 2 hours per day. A common AC watermaker for this boat is a 600 gallons per day (gpd) or 25 gph unit making 50 gallons in 2 hours, In ideal conditions only. Most likely, this boat will have a minimum of 100 amps of DC charging from an inverter or charger, supplying ample usable amps to the batteries in that same 2 hours. The Spectra Newport 400 watermaker can supply 32 gallons in 2 hours in almost any conditions. If more water is needed, production can continue for several hours without depleting the battery bank cutting generator run time by more than half.

Even more efficiency can be obtained with the Catalina 300 utilizing the super efficient Spectra Mag Drive feed water pump. However, if a lot more water is needed the Newport series 700 and 1000 gallon per day units can provide 27 and 41 gallons per hour respectively on 24 Volts DC with an option of 110/220 Volts AC for the larger boat.

Often an AC watermaker is noisier than the generator that runs it. Spectra watermakers are the quietest high performance watermakers available. You will hardly know it’s running even with the generator off.

With an AC watermaker all your eggs are in one basket. If the generator quits or you are in an area where running the generator is inappropriate, no water can be made. With a Spectra unit, water can still be made from the batteries, which are charged from the main engines or other sources such as wind and solar chargers. This adds a natural redundancy to the watermaker, making it far more reliable.

Eliminating the need to run the generator to make water while underway not only saves fuel, but wear and tear in all the systems.  A generator is sized according to the loads expected. AC watermakers, along with air conditioning units, are some of the main factors considered in choosing the proper genset. A more efficient watermaker will allow the option of using a smaller and lighter, quieter and less expensive generator. The Spectra 700 and 1000 GPD units come standard with “soft start” Variable Frequency Drives which will allow the system to start on small gensets or inverters.

Most of the AC watermakers on the market today use components drawn from non-marine sources and are adapted for marine use. They incorporate high speed reciprocating pumps with crank cases and oil sumps, belt drives or spider couplings, oil seals, external high pressure seals, large AC motors, pressure controls, high pressure safety cut out switches, low pressure cut out switches, expensive and high maintenance centrifugal boost pumps, and lots of little internal moving metal parts and springs exposed to salt water and vibration.

Spectra watermakers do not have or need any of this. Our “purpose built” pressure intensifier, the patented Clark Pump, is designed from the ground up to withstand the rigors of watermaker life. It is non-corrosive, has no external moving parts and shaft seals, no metal moving parts, no oil, and operates in slow motion. It will run for thousands of hours with no maintenance needed. It is run hydraulically by water flow from a feed pump that is constructed of Stainless Steel  self priming, maintenance free, inexpensive, quiet, and can be mounted almost anywhere on board, even up to 4 feet above the waterline.   Because of the unique high pressure system design, no pressure adjustments are necessary even if the unit is run in brackish water.

AC watermakers have been the only practical choice on power yachts for many years and even with their drawbacks have served the marine industry admirably but now there is an alternative that simply offers more thanks to Spectra Watermachines.

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