Dic King of Plymouth, Massachusetts, asks:
Last year several friends and I used a product called PropSpeed from West Marine to protect our props and shafts against fouling. One $300 kit covered about 10 to 12 sailboat props and shafts, and worked very well. Another boater we know treated his prop and shaft with a zinc spray paint (93 percent zinc) that he bought at Home Depot for $10. The zinc spray sounds like a good deal, but before using it I want to know if there is any downside to using a product like this in a marine environment.
Don Casey replies:
A zinc coating should not have any detrimental effect. To the contrary, it should protect the underlying bronze or steel from corrosion, although it should not be used on an aluminum prop. There are a lot of anecdotal reports from boaters who believe zinc coatings keep their props relatively barnacle-free. Results may vary depending on how much time is spent underway, the rotational speed of the prop and the specific fouling environment. If it doesn’t work out, you can always go back to PropSpeed.
As an aside, I keep my prop clean in the tropics with a heavy application of paste wax. I have also heard that surfboard wax works well. It reportedly lasts longer and can be reapplied underwater.