Mild Steel Mast Furniture

[bott]

Hello,

I am re-doing the rig on my gaff cutter and came to the conclusion that I need a different arrangement of lugs on the mast band where the shrouds attach. Specifically, I want another lug added to the aft side for the swifter shrouds to attach.

The current band is 6" in diameter, 1.25" tall, and ~5/16" thick. The local welders I talked to were reluctant to try to weld/braze a new lug on the existing one, because I don't know what the specific alloy of the band is now.

So I am thinking of making my own out of mild steel, and have found a good starting point from heavy-duty pipe hangers, mild steel, with all the same dimensions as the bronze band but 1/4" thick. Then I can have lugs welded on from there, whatever dimensions I need (probably thicker just to have a good landing area on the band itself).

Does this sounds like a workable solution? The boat is ~20,000 lbs with ~800 sq ft of working sail. The band is also well supported underneath by 4 bolster blocks. From there, I would either have the piece galvinized or maybe powder coated. But its going to be ~40' in the air pretty far from the salt water.

Thanks for any opinions shared!

Eric

[andrewe]

No problem with the strength, this is a common solution. But galvanizing is the only treatment to use. I read somewhere that galvanizing plus proper primer and paint is more protective than the sum of it's parts. It may be 40ft up, but the movement of the rigging will get through powder coating pretty fast and start rusting.
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[KAIROS]

My boat's mast fittings are the original galvanized mild steel, 46 years in service. I just stripped them of the old paint and varnish splatters, then painted them with Hamerite primer made for galvanized metals and painted them. The primer was suspiciously like latex paint, but I don't know if it is the same thing.

The result looks good but the finish is not very durable. On the mast it is fine, but on newly-galvanized deck fittings the paint chips and wears off quickly. Folks that seem to know tell me that nothing really sticks to galvanizing. Because of my experience, with the paints I used, I won't bother painting again...in fact I might strip the deck fittings so I don't have to maintain the paint.

Maybe others have found a tried and true paint system that really sticks to galvanizing?

[peter radclyffe]

good idea , maybe make it in 2 semicircles with bolts for adjustment, what are swifter shrouds, backstays ?

[KAIROS]

...maybe make it in 2 semicircles with bolts...

It is nice to be able to remove it easily. Two halves bolted together works for that.

[bott]

good idea , maybe make it in 2 semicircles with bolts for adjustment, what are swifter shrouds, backstays ?

Yeah, the old part and the potential new ones are both built like that.

And swifters ('round here) are the aft shroud pairs... they provide a little headstay support, nothing like the running backs though.

[bruce w]

use hot dip galvanized bolts with double nuts ,not stainless.

[donald branscom]

I would use hot dip galvanizing process.

[bott]

I would use hot dip galvanizing process.

Yes, I found some good galvanizers very close to me. Now I just need to figure out how to prep and paint it. Its only going to be this one part, so I dont want to buy quarts of paint and primer... rustoleum?

Also, it is sounding like a 1/4" band is totally sufficient?

[peter radclyffe]

3/8" would be better, the increased weight in this instance is comparitively irrelevant

[bott]

3/8" would be better, the increased weight in this instance is comparitively irrelevant

With the split-ring band, I was planning on attaching one shroud to each side where the band doubles for the thru-bolt, making it more like a 1/2" tang. Then weld 3/8" tangs onto that for the forestay, swifter and running back attachments.

Then it seems that the 1/4" part of the band is under compression loads, and the tangs under the shear/pulling loads will be sufficiently thicker.

Does that engineering reasoning make sense?

[George Ray]

Why not stay with what has worked for so long..... 5/16" ?

[KAIROS]

....good galvanizers very close to me. Now I just need to figure out how to prep and paint it. Its only going to be this one part, so I dont want to buy quarts of paint and primer... rustoleum?...

I used Scott (http://www.scottgalvanizingco.com/), Ace, and Emerald galvanizing there in Seattle. I think Scott is definitely the one for small jobs like this. You pay for a minimum weight of metal, so make a pile of other stuff to go with the mast band. I had all my fittings and my 2 anchors and a friends anchor done all for the minumum price of something like $100.

Abrade the galvanizing with fine sandpaper/garnet, and clean it with solvent, and try whatever for paint. I asked for help here on painting galvanizing and it seems nothing sticks to it well.

[bott]

Why not stay with what has worked for so long..... 5/16" ?

Only because of the available dimensions of the hangars that *may* be a good starting point instead of having one custom fab'd from scratch.

But, if there is something like a $100 minimum charge for galvanizing, it makes just ponying up the ~$250 for a finished bronze piece form the PT foundry more appealing.

[KAIROS]

....if there is something like a $100 minimum charge for galvanizing, it makes just ponying up the ~$250 for a finished bronze piece form the PT foundry more appealing.

My deck fittings would have been $10,000 at the foundary in bronze, or $1000 in mild steel plus the $100 galvanizing. So, it was an easier choice for me.

Especially at the masthead where appearance is not that important, bronze seems a waste. Up there a galvanized fitting would last for......maybe longer than the rest of the boat.

[andrewe]

I used to use a two component primer from Robbilac called 'Primer filler surfacer'. It had an etching action and stuck very well. Robbilac might be part of the Berger group now. Used to brush or spray, but need a good mask for spraying.
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