Here is an idea on how to keep bottom paint on your prop longer. I generally get 12-16 months of a clean prop here in Florida which is about as bad as it gets in the marine growth department. After this time, I’ll begin to get barnacles, and when removing small barnacles, I tend to also remove the paint on the prop and it’s all down hill from here.
Fouled props have been a problem for sailors for a long time, and it seems to me that the guys at the paint companies are not paying enough attention to it. Why can’t these big companies solve this issue? Pettit has an underwater running gear kit, or they used to, but I tried that too, and it was not very good. It’s key ingredient was “Tie Coat” that was supposed to give good adhesion between the metal primer and the bottom paint. I don’t think to much of this. Unfortunately, this is what a lot of boat yards still use.
Here’s my secret. Instead of Tie Coat, use Epoxy Barrier Coat 2000 by Interlux. This is the stuff you would normally use to provide a barrier to blisters after you have stripped the bottom paint off your boat. It’s a two part epoxy system, the paint and a catalyst. I use Pettit’s underwater metal primer first, then the barrier coat, then a couple of coats of bottom paint. I paint the first of coat of bottom paint on before the barrier coat is completely dry. Then, when dry, I lightly sand, clean, and apply a second coat. I think the key to this working well is the adhesion of the barrier coat to the prop.
I suggest you get a bunch of friends at your sailing club to go in together on this because you only need an ounce of the metal primer and an ounce of the barrier coat for one prop. A quart can of these items can do a lot of props and shafts. They are not cheap either.
UPDATE: Jan 2015.
I have studied this subject for at least a decade and I think I’ve seen just about all the possible solutions. As Don Casey puts it; “If I had the definitive answer on how to keep propellers clean in seawater, I would be cruising in the south of France while my prop-coating company made fat deposits into my personal account.” I feel the same way. I actually was breaking down my large quantities into small kits for my friends and charging a small fee for the “Silver Bullet Prop Kit”. This helped me reduce the cost for everyone, myself included.
I’ve heard it all. Ideas about using a magic marker, baking STP oil treatment on the prop in the oven, sex wax, copper coatings, Barnacle Buster Spray paint, and more recently products like Velox, Propshield, Prop Glop, and Propspeed. Of all of these, Propspeed has some merit. I think the jury is still out on Velox, and Prop Glob is a short term solution as is Sex Wax.
I heard from Skip on “Flying Pig’ that he has used Propspeed successfully for two years. I read another account like this too. Then again, I’ve read several accounts of this not working so well if your boat sits a lot. I think this could be a good solution as Skip suggests for boats that get going now and again. He also says that if you do get a little growth on the Propspeed, it wipes right off, just like slime on the hull. At $200 for a kit that can treat about two props and shafts, it might be a good idea to find someone to share a kit with. Even so, if you can get two plus years out of it, it sounds worth it.
If you’d like my installation instructions for doing it my way with the barrier coat, drop me an email at email@example.com and I’ll email them to you.