Outdrives are difficult to keep free of growth. The main reason for this is that traditional copper-based bottom paints cannot be used on an aluminum outdrive. Doing so will result in serious corrosion from the aluminum reacting to the copper in the paint.

When painting an aluminum outdrive you must use a copper-free bottom paint. There are a couple of different brands out there: Interlux, Blue Water Marine, and Sea Hawk to name a few. However, you will get the best possible results with Tuff Stuff Primer and Colorkote.

The Outdrive Paint shows best results when paired with a primer such as Tuff Stuff. These products are usually applied by brush and roller.

An alternative to painting is a foul release system, such as PropGlide. For more information on Propglide, see this How To Article.