Ask SAIL: Best Anti-fouling for your Prop

I have a 2006 Najad 440 center-cockpit sloop with a 75hp Volvo saildrive. Last summer I kept the boat at a marina in Harpswell, Maine, and as the season progressed, I noticed it was slower under power. When I hauled her in the fall, the bottom was clean as a whistle (thanks to Sea Hawk AF-33 paint), but the bronze propeller blades and hub were completely covered with barnacles. I would like to put antifouling paint on the propeller. I’ve researched the topic, but have found no definitive answers as to whether it’s a good idea.
Author:
Publish date:

Nick Orem of Newbury, Massachusetts asks:

 I have a 2006 Najad 440 center-cockpit sloop with a 75hp Volvo saildrive. Last summer I kept the boat at a marina in Harpswell, Maine, and as the season progressed, I noticed it was slower under power. When I hauled her in the fall, the bottom was clean as a whistle (thanks to Sea Hawk AF-33 paint), but the bronze propeller blades and hub were completely covered with barnacles. I would like to put antifouling paint on the propeller. I’ve researched the topic, but have found no definitive answers as to whether it’s a good idea.

Don Casey replies:

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.

DonCasey_1

You can paint a bronze prop, but not with paint that contains copper. You also have an aluminum saildrive leg, and I wonder how you keep that clean. Normally the same antifouling should be used for both the leg and prop, but if your leg has been barrier-coated, then painted with a copper paint (high-risk behavior, in my opinion), you’ll have to use a different paint on the prop. If your saildrive has a copper-free coating, you can also apply that to your bronze prop, but only after priming the bronze with an epoxy-based barrier coat.

Another popular option is to use a zinc-rich aerosol paint, such as Pettit’s Barnacle Barrier, or the similar but cheaper “cold galvanizing” sprays available at home-supply stores. This has the appeal of being simple, inexpensive and risk-free.

Instead of painting you could also try a silicone-based coating, such as Propspeed, a lanolin coating like Propshield, or a heavy wax, such as Sex Wax surfboard wax. Propspeed is highly praised, but is relatively expensive and must be carefully applied. It also depends on motion to keep props clean, so it may be less effective on a sailboat that sits idle or rarely runs under power. Propshield and similar products have a relatively short life span, not more than six months. A wax coating will last an even shorter period, but some can be reapplied underwater.

Related

TOTW_PromoSite

SAIL's Tip of the Week

Presented by Vetus-Maxwell. Got a tip? Send it to sailmail@sailmagazine.com No chafe, safe stay  If you’re leaving the boat unattended for a longish period, there’s a lot to be said for cow-hitching the shorelines, as this sailor did. They’ll never let go, and so long as the ...read more

belize600x

Charter Special: Belize

It would be hard to imagine a more secure spot than the Sunsail base on the outskirts of the beachside community of Placencia, Belize. The entire marina is protected by a robust seawall with a channel scarcely a few boatlengths across. It’s also located far enough up Placencia ...read more

DSC00247

DIY: a Top-to-Bottom Refit

I found my sailing “dream boat” in the spring of 1979 while racing on Lake St. Clair in Michigan. Everyone had heard about the hot new boat in town, and we were anxiously awaiting the appearance of this new Pearson 40. She made it to the starting line just before the race ...read more

01-oysteryachts-regattas-loropiana2016_063

Light-air Sails and How to Handle Them

In the second of a two-part series on light-air sails, Rupert Holmes looks at how today’s furling gear has revolutionized sail handling off the wind. Read part 1 here. It’s easy to look at long-distance racing yachts of 60ft and above with multiple downwind sails set on roller ...read more

HanseCharles

Video Tour: Hanse 348

“It’s a smaller-size Hanse cruiser, but with some big-boat features,” says SAIL’s Cruising Editor, Charles J. Doane. At last fall’s Annapolis Boat Show, Doane had a chance to take a close look at the new Hanse 348. Some of the boat’s highlights include under-deck galleries for ...read more

amalfitown

Charter Destination: Amalfi Coast

Prego! Weeks after returning from our Italian flotilla trip last summer, I was still feeling the relaxed atmosphere of the Amalfi Coast. It’s a Mediterranean paradise, with crystal-clear waters, charming hillside towns and cliffside villages, plenty of delicious food and wine, ...read more

image005

Inside or Outside When Sailing the ICW

Last April, my wife, Marjorie, and I decided to take our Tartan 4100, Meri, north to Maryland from her winter home in Hobe Sound, Florida. This, in turn, meant deciding whether to stay in the “Ditch” for the duration or go offshore part of the way. Although we had both been ...read more

MK1_30542

SailGP: There’s a New Sailing Series in Town

San Francisco was the venue of the biggest come-from-behind victory in the history of the America’s Cup when Oracle Team USA beat Emirates Team New Zealand in 2013, so it seems only fitting that the first American round of Larry Ellison’s new SailGP pro sailing series will be ...read more