Reward for lost Kraken!
Join Date: Apr 2006
Thanked 138 Times in 135 Posts
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That's how they work. They foul. Marker pens...Come on, I've got a bridge to sell you.
When you close up the boat, you pull the impeller. EVERY TIME. When you are getting set to race, you stick it back in. And every time you pull the impeller, you look it over and clean it with a toothbrush or vegetable brush to get the critters and weed out.
Don't like that? Ante up, you can buy an ultrasonic speedo kit, something like a low four figure price, just like the pros do.
For plain cruising? Use the one on the GPS.
Some folks use transducer paint (special antifouling paint $$) or tin antifouling paint (illegal for this use) and try to paint some in there as best as they can. But that's just going to slow the growth, your best bet is still to pull the paddelwheel when you are not using it.