As I prepare to barrier coat (interlux interprotect over west system epoxy) and bottom paint (Pettit Trinidad hard epoxy) Merry, I’ve also begun to fit new bronze underwater hardware, including rudder pintles and gudgeons, bobstay chainplate, and through-hull fittings.
I am not sure of the most modern and correct way to treat this underwater hardware - should it be primed with an epoxy barrier coat and then painted with hard anti-fouling paint? Would you also treat bolts and nuts this way? Strainers?
I don’t mind diving and scrubbing the hull, fouling is not my major concern. Preventing corrosion, electrolysis, and making sure that things are long-lasting and serviceable are. I hope this pile of new bronze hardware lasts a very long time.
So, what does the group think?
From Interlux:
PAINTING TRIM TABS, SHAFTS, STRUTS, PROPS AND THRU HULL FITTINGS.
Degrease the metal surface with Fiberglass Solvent Wash 202 or Special Thinner 216.
Bring metal to a uniform bright finish by sandblasting with non-ferrous blast media such as clean
silica sand or grind using coarse to medium emery cloth. Remove blast or sanding residue.
Apply one thin coat of Viny-Lux Primewash 353/354 thinned 25% with Viny-Lux Solvent 355.
Allow Viny-Lux Primewash 353/354 to dry a minimum of one hour but no more then
24 hours and apply three coats of InterProtect® 2000E/2001E following dry times on label.
(If fairing is necessary, fair between first and second coats of InterProtect®).
Apply 2-3 coats of Interlux® antifouling paint. Hard antifouling paints work best such as
Fiberglass Bottomkote® or Ultra for this application. On aluminum use Trilux® 33® or Tri-Lux® II.
Note:If dry times for InterProtect® cannot be followed use the following alternate system. Apply four
coats of Primocon YPA984 over the Viny-Lux® Primewash 353/354. On rivets and weld seams
apply a minimum of five coats. Finish with at least three coats of antifouling paint. When painting
aluminum use Trilux® 33®, Tri-Lux® II Trilux® Prop & Drive or Trilux® antifouling paints.
No interprotect over pintles and gudgeons. Antifouling pintles, gudgeons- yes. That way it is easier to inspect for cracks amd damage (thinner coating).Interprotect is thick.
If the thruhulls are not yet installed, interprotect, install thru hulls, then antifouling. Either way it will be ok. Depends on the amount of prep work you want to do. Corrosion and electrolysis of thruhulls I do not think will be prevented from interprotect or antifouling. Ensuring no dissimilar metals in the installation will. The benefit of the interprotect is preventing osmotic blistering, but it is a good primer.
Execpt for zincs- no coatings on zincs.
I’ve never had any problems with corrosion on underwater bronze. If you have electrolysis issues (desn’t sound like you do), the remedy is not paint and coatings. Nor do I think paint/coatings would be much of an effective preventative for electrolysis damage, as invariably some part of the coated bronze remains wet. So then you’d just have electrolysis going on hidden away underneath your coating.
The primary thorn i have with my underwater bronze is barnacles. Those buggers seem to have radar for metals. And they don’t seem to much care if you slober antifouling over the metal. I’ve given up antifouling underwater metals and instead just spray paint them with a few coats of “cold galvanizing” (spray on zinc). Zincs seem to get fewer barnacles - and I swear my zinc covered bronze gets fewer barnacles than antifouling covered bronze. And i get a slight protective edge to boot. I just lightly disc sand and recoat/spray between seasons. And the stuff is dirt cheap!
thank you for the tips, good stuff to think about and good to know how others on the group are doing it.
One thing to clarify - the reason I was considering priming the bronze with interprotect is to protect the bronze and the antifouling paint from one another, as I’ve heard of the copper antifouling paint and the bronze hardware having electrical reactions when bronze is painted with copper antifouling paint. And I’ve got lots of Interprotect and their documentation was recommending it as a solution for this problem. It sounds like this reaction is not something that BCC owners are experiencing much.
I had not considered the importance of being able to inspect the bronze for cracks. This makes good sense.