Letter 27000

Painting HDG steel for use in salt water  

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I have had a new mild steel rudder fabricated and flux core welded for my 40' sailboat. The spine of the weldment is a 3" dia. steel pipe with plate welded to it. I have had a local galvanizer in Houston HDG it for me.

The rudder will be used in saltwater with the lower 2/3 submerged at all times. My question is one of finishing. I want to paint the finished rudder asap and am wondering what priming process will be required since the HDG will be fresh. The paint will be a high gloss two part polyurethane. I have no experience using HDG steel since the rest of my boat is of fiberglass covered wood construction. Will I need Zincs for sacrificial purposes? Thanks for your help.

Michael J. Howsley
amateur boat builder - DeRidder, Louisiana

There are primers for galvanize [Galvanized Metal Primer [link is to product info at Amazon]]. In the dark ages, it contained a lot of zinc chromate which is hard to come by now. Check with several paint stores.You might find some information at major paint manufactures web sites. Sacrificial zinc is normal isn't it?

James Watts
- Navarre, Florida

Michael,

l. I sure like your use of a 2 component Urethane. Very high surface finish. Expensive. Very abrasion resistant.

2. Re sacrificial anodes ... not necessary IF, IF, IF the entire surface were painted.

I'd be worried/concerned about the spindle holders (I don't know what the right nautical term is) through which the shaft protrudes ... (gudgeon pin???) and would strongly recommend some type of non-metallic sleeve or O-ring set-up to prevent the metal from galling. And painting the fresh surface? I wouldn't worry too much. The Urethane is a fairly flexible paint and should anyhow 'shrink around' any parts as it probably has a l0% shrinkage factor upon curing.

Freeman Newton
- White Rock, B.C. Canada

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