Hi CRYSTAL,
I've just installed an NRG Ultrasonic Antifouling system, and have had it running since February 28 2015. The system consists of two transducers on my B36, one located under the floorboard in way of the bottom of the companionway, and the other inside the fore cabin under bunk locker at the aft end of that space. The aft transducer is mounted on the centre line, while the forward one is located on the port side, but as near as possible to the centreline. Power comes from two dedicated 110ah 12 volt batteries specifically installed to run the system and which are currently charged from a feed via a charge regulator from my wind generator. Having said that, the wind generator has had a problem for the last couple of weeks at least and has not provided any charge at all in that time, but the ultrasonic system has run continuously without yet discharging the batteries. Onboard yesterday the batteries were showing 12.2 volts, but I did not record the voltage at the start when the batteries were both brand new. One thing I was concerned about was whether the ultrasonic system would make any noise that might keep one awake at night, and up to now I've spent three nights onboard and have not heard the system at all. Indeed, I had wondered whether it was doing anything at all and the only possible evidence of something happening that had not occurred before installation is that when going onboard and operating the toilet pump, the usual flurry of incoming seaweed, marine fauna etc., has all disappeared. The boat has remained afloat throughout the winter and until the ultrasonics were installed had been a haven for everything that was going around. In a couple of weeks the boat will be hauled out for the hull to be pressure washed off and I will antifoul the underwater area using exactly the same coating as previously, so it will be another year before you have any definitive word on whether it works or not. Up to now the usual antifouling paint, Cruiser Uno, has not really been up to coping with the situation with the result that after five months the hull has been looking like a fur coat, and through the winter when the boat rarely moves the bottom begins to resemble a forest of weed.
More to follow in due course.