Polaris has a Sonihull Duo ultrasonic antifouling system installed. This system works in conjunction with the classic antifouling paint and should give additional protection from hull fouling.
The working principle is simple: waterborne microorganisms like bacteria and algae growing on the hull are the basis for fouling. Larger organisms like barnacles feed on these microorganisms and attach to the hull which slows down the boat, causes damage and may even block rudders, propellers and seacocks. The ultrasonic antifouling system transmits ultrasonic waves via transducers fixed to the hull inside the boat, a bit like a drumstick on a drum. These ultrasonic wave pulses damage the cell structure of bacteria and algae, inhibiting them from attaching to the hull. This, in turn, does not provide a feeding ground for larger organisms and they will not grow on the hull.
The system is completely inaudible to the human ear and is harmless to other marine life. In fact, this technology is used to protect industrial fish farms from fouling.
As a side effect, ultrasonic waves are also transmitted to the water and fuel tanks as long as these are in direct contact with the hull. The system kills bacteria and germs in the water tanks and inhibits the diesel bug bacteria from growing.
In combination with a classic antifouling paint applied this should give enhanced antifouling protection.
We will monitor the efficiency of the system and I will update this page in the coming months.
For further information on the system please visit the dealer’s website.
Update:
WWehave now had the Sonihull Duo (with two ultrasound transducers) installed for a year. POLARIS was always in the water in Portsmouth, an area known for quite strong fouling. We had her lifted in July 2017, October 2017 and March 2018, every 4 months to give her a scrub and to change the anodes on the sail drive. At every lift out we noted a build up of a slight slimy layer on the hull which was easily removed with the pressure washer. There was no build up of barnacles or similar on the hull and keel. Two areas where the system seems not to be fully efficient are the rudders and the sail drive. The rudders, due to their flexible fitting to the boat probably receive less direct ultrasound waves through the hull which, so far, has led to a slightly stronger growth of algae, however, these can be easily brushed off with a broom in the marina. No barnacles have grown on the rudders. The sail drive is mechanically isolated from the hull and receives no direct ultrasound waves from the hull. There the growth of algae was quite significant and there grew some small barnacles (2-3mm) which can be easily scratched off with the fingernail.
Update March 2018:
We decided not to renew the antifouling paint for the coming season as I hoped with the Sonihull system we would have enough protection. We shall see in a couple of months whether this assumption holds up but in principle, it would exactly be what was expected: significantly lower use of antifouling. If we can reduce antifouling to be applied only every second year, this would be a significant reduction in maintenance cost.
Update September 2018:
Over the summer we saw heavy greenery growing at the waterline and on the twin rudders, certainly also helped by the extraordinarily warm summer and high water temperatures. We did not move the boat as much as the year before, but clearly, the antifouling paint which was applied a year before started to lose its effect and whilst the Sonihull system did its job the hull started to foul in the areas further away from the transducers and in areas with high sunlight exposure.
Update October 2018:
We decided to bite the bullet and go for Coppercoat antifouling, apparently the ideal combination with the Sonihull system, according to the dealer. We left Polaris at Desty Marine at Hamble Point Marina for the job. Took them 2 weeks with the boat in a temperature and humidity controlled environment, probably also a good idea to let the boat dry out after 1 1/2 years in the water. Update follows – keep tuned….
Update November 2019:
Coppercoat and Sonihull seem to work well in tandem. We had a lift out in mid summer and another one in October, both for a quick pressure wash of the hull. No mussels, barnacles or serpulids attached to the hull, just a slight algae slime which washed down well under power jet.