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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
First of two simultaneous responses -- ++++
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
Second of two simultaneous responses -- ++++
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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