I uses PropShield. Its lanolin base. It really reduces barnacles growth. But it doesn't last very long. 6months tops. Still need to dive under to nick barnacles off (not scrap) ocassionally. My friend uses PropSpeed with good results but pricey. I just coat it last weekend. Previous time was Oct2009.
2002 Hunter 326, SV Millennium 2
1999 Macgregor 26X, SV Millennium