In the April edition of Ask Sail, Nigel Calder asked readers to share ideas on how best to keep their props clean. The Q and A from the magazine sparked a discussion with readers chiming in from all corners of the country. Here are some of their ideas:
Q: What do you recommend for keeping barnacles from growing on my prop, strut and shaft? For years, I've used metal and bottom paint, but have had little success. Is there anything else that will adhere better to the prop, strut and shaft to prevent bankable build up? Most paints seem to be shaken off by the turning of the prop when the boat is underway. – Clem Galliard, Rye New York
A: For some reason I’ve always had very good luck when I have painted my prop, even when I am cruising in warm nutrient–rich water. However, I also know others who have not been so lucky. Unfortunately, I really don’t know what has made the difference with my gear. I have always used the best paint I can find and have had good success with Pettit's Trinidad, which is 70 percent cuprous oxide (pettitpaint.com.) I hope other SAIL readers with good suggestions will send them in to firstname.lastname@example.org. As an aside, I have done a lot of propeller testing recently and it is clear that even though paint does have some effect on a propeller’s performance, it is far less compared to what can happen once weeds and barnacles get on the blades! – Nigel Calder
Patrick Childress writes: Greetings from South Minerva Reef. Like Clem Galliard, I too have had little success keeping primer and antifouling paint attached to my bronze prop and stainless steel drive shaft. I now have a feathering Kiwiprop (LINK!) on our Valiant 40. The stainless steel parts of the Kiwiprop hub cannot tolerate a build up of antifouling paint. While in New Zealand I discovered a lanolin/fish oil product called LanoCote made by CRC in Auckland, NZ. It is primarily used as a tenacious anti-seize coating. Since this is a relatively new product to me I have to rely on the results of other cruisers. They say, applied to the metal parts of a prop and shaft its water shedding capabilities does not allow it to wash away for several months and marine growth will not attach to it. Although the directions say to apply it to a dry surface other cruisers have found success reapplying it under water. After 3 weeks on the Kiwiprop and my stainless drive shaft, everything looks like the day our boat was put back in the water. With the warmer waters up ahead in Fiji, I will be able to closely monitor its performance.
John Tesoriero writes: I have used the same method for the past ten years and never have more than one or two barnacles on my prop or shaft. I clean the stainless steel shaft and bronze prop down to clean metal with a wire brush on an electric drill. Wipe with solvent and apply two coats of a non-metallic primer. I have used Interprotect successfully but other non-metallic primers work as well. I then apply two coats of any available copper based bottom paint and splash the boat. Don't prime or paint under or over the zincs. As I said, little to no fouling after six+ months. I use the boat almost every weekend and motor perhaps for 30-60 minutes total each time we take the boat out. By the end of the season, the paint has worn off the tips and parts of the prop blades but is intact elsewhere.
I have tried this method without the primer and always got bad fouling of the prop and shaft. Interlux outdrive spray works well if used with their primer but is more expensive. I have heard others theorize that the electrolysis current set up between the metal shaft/prop and plain copper paint somehow keeps the copper inactive and thus allows barnacle fouling. A non-metallic barrier coat of primer stops this interaction and allows the copper to inhibit growth. This is the theory and the model seems to work on my boat.
I sail in the salt waters of Barnegat Bay NJ and keep the boat in Forked River - a somewhat brackish river feeding the bay.
Bill Boyeson writes: Nigel Calder asks readers to send in good suggestions regarding a prop paint. I have a 3 bladed Max Prop that I coat with Pettit’s Zinc Coat Barnacle Barrier. It comes in a 16 oz spray can and is built up with several coats. It not only prevents barnacles for up to two seasons it almost eliminates the need to change the cone shaped zinc on the propeller. Our boat is used in the usually cold waters of Puget Sound.
Bill Sherman writes: Last year, my surveyor informed me that if I need to use anti-fouling paint on my prop, I was to coat the bronze prop with epoxy before painting with anti fouling because the anti-fouling properties can cause problems with most bronze props.
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