Udder cream anyone???

Sorry to interrupt the fun, but wouldn't it be possible to zap organisms which attempt to make a home on bare metal surfaces, by sending some mild electric intermittent pulse through the shaft & prop? Not enough to send boiled langoustines to the surface at the stern, ready to eat, just enough to discourage barnacles.
 
dancrane said:
Sorry to interrupt the fun, but wouldn't it be possible to zap organisms which attempt to make a home on bare metal surfaces, by sending some mild electric intermittent pulse through the shaft & prop? Not enough to send boiled langoustines to the surface at the stern, ready to eat, just enough to discourage barnacles.
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Interesting thought. Ultrasonic systems are already available for hulls but I thought that they weren't effective on props. (probably difficult to get a good coupling between transducer and rotating shaft). I imagine that there'd be problems with corrosion unless DC wasn't used. In fact, I imagine that there's more chance of high frequency electrical pulses interfering with cellular processes than simple DC. A symmetrical AC pulse should also cancel out any corrosion you'd get with DC pulses. It might be also better suited than ultrasound to protecting something relatively small (e.g. a prop.) rather than a whole hull (made out of fairly non-conductive material).

I'll stick to Equimins (or Waxoyl) until someone does some research on it. Annual cost so far with Equimins is probably around 10p so difficult act to follow (assuming I'm not imagining the benefit).
 
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Thanks for that Mistroma. On a similar line, I asked a few months back about 'green' antifouling options and the unexpected reply came that if the boat is kept in alternately fresh and salt water zones, the little critters which are happy in one, can't survive in the other, and drop off. Sounds great...

...but not very useful unless your marina has a river flowing through it perhaps. Still, if it was possible to 'bag' the propellor and visible shaft in a plastic sack with a nozzle for a hose and a controllable exit valve, the metal could be bathed in fresh until you go to sea, then bathed again when you moor up.

I liked the idea of the whole-hull-bags which use the same fresh/salt water change to make antifouling redundant, but they don't seem to have been chosen by many yachtsmen. Sad.
 
We started taking our previous boat through the Forth & Clyde canal many years ago. The hull and prop. were always pretty clean by the time we'd travelled to East coast and lifted for the winter. The effect seems to be real and I assumed that growth fell off as cells exploded due to osmotic pressure and organisms died. Might be something else entirely but it seemed reasonable that salt water organisms would suffer from excess fresh water transitioning across the cell wall.

I imagine that it would still take a while to kill off growth. I'd probably need to dribble fresh water into a flexible cover for a few days in a marina. Simpler to scrape the prop. clean if I do dive part way through the season next year. Or anchor in fresh water for a few days if I can find a suitable river as mentioned. :D
 
We tried lanolin on the basis that if the surface was slippery nothing would grow on it - this is the basis of Prop Speed and polishing the prop to a mirror finish. It was suggested that not only to apply lanolin but heat the prop first, and apply hot. We did not try that. Many of the latest coatings, the lfuoro-polymers work on the same basis - produce a coating to which marine growth will not stick. Udder cream might have two mechanisms, the non-stick one and also contain an active ingredient (or two). Obviously if it washes off it then will not work but our experience suggests the lanolin stays there.

Jonathan
 
Udder cream is indeed brilliant - but don't use it on the prop - rub it everywhere exposed to the Sun and it will protect you from the worst results of sunburn ! Excellent stuff !
 
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