Great news. We are hauling out in April and will report back then.

I report on 12 months usage. A green slime that wipes off with a cloth and a few barnacles between rudder and Skeg. In tropical water for 9 of the last 12 months.

I have cleaned her with a cloth and a snorkel every thee months, otherwise no maintenance. Based upon this weeks examination ( wet suit -water temp 10 degrees) I will leave it now to Te haul out in May. 17 months. The thing paid for itself in 6 months....

Result!

I fitted one of these in New Zealand in December. The cost was half what I expect to pay for a haul out and two coats of conventional anti foul to be applied.

As the same time as the ultra sound was fitted, she was scrubbed down and new anti-foul applied.

To my complete surprise the results have been rather good. Five and a half months in, including the last two in quite warm water there is no growth of any kind on the hull - no barnacles, no coral type growth - just, as Simon said, a slime which comes off with a cloth.

May that please continue..........

Unscientific I know but I 'd say my home made Ultrasound worked really rather well. After 11 months (the last 6 of which were spent sitting in a marina) she came out with just slime and no barnacles hanging off the prop. Really rather pleased!

I 've no idea whether it works but my project for this winter was to make an ultrasonic anti fouling system. There are quite a few expensive commercial systems out there that promise much but with flimsy evidence. I bought a kit from Australia and have happily been soldering away. The cost of course was a tiny fraction of an 'off the shelf ' product. My guess is that it probably will have minimal effect but it 's been fun building it and I discovered loads about electronics on the way.

Finally completed it today and pressed the the button to hear a series of "whale-like" utterances. All very exciting seeing my first electronics project come to fruition. We will fit to the hull next week and will keep you updated as to what happens. It will certainly deter dogs but if it deters barnacles too that will be a bonus!

Simon