... and follow the directions on the can. It's clear and a bit runny so I find it better to do 3 thin coats using a foam brush, to avoid runs or sags that could affect balance or flow of water over the blades. As a final step I also use a Q-tip to stuff the holes of hex-head set-screws with desitin cream (the stuff for diaper rash; it's made from lanolin and zinc oxide) it does stay in the recesses and prevents growth -- makes it easy to use a hex key at the end of the season.

One year I did try desitin cream on the entire prop and shaft, but it washed off except inside the recesses. I suppose you could easily reapply it underwater, but I didn't -- once the surfaces had growth it seemed pointless. Never tried the magic marker. Any other urban legends to try?

PS -- don't get me started on the sewage releases. Greenwich released over 28 million gallons of raw sewage and all we hear is silence http://www.greenwichtime.com/default/article/One-year-later-Cos-Cob-sewage-spill-remains-a-284923.php and millions of geese shit in the streams that feed LIS, but if just one boater craps in the water it's a major crime. Don't get me wrong -- I'm not in favor of boaters pumping overboard in a densely populated closed body of water like LIS, but the hypocrisy just kills me! The town employees don't care if the taxpayers get fined -- it doesn't hit those responsible where it hurts for improperly managing and operating the facilities.