Upkeep on 40yo mast

[zachduckworth]

I have a 1984 Islander Bahama 30 with an anodized Kenyon mast. I’ve had the boat for a year. The rigging is 13 years old and I’m planning on re-rigging it next year. While the mast is pulled I want to perform some much needed maintenance on the mast. The bedding on the hardware has failed and there is quite a bit of corrosion around the stainless steel fittings. I’d like to strip the anodizing, re-bef the stainless fittings with Tef-Coat, and replaced all the sheaves.

I want to keep the mast natural aluminum to make it as long-lived as possible. Given that there is already some corrosion to deal with, what is the best way to remove the existing annodization, remove the corrosion, and get back to bare aluminum? I am in Long Beach, CA, if anyone has local recommendations. Thanks!

[neilpride]

To repair the places where the SS hardware has created corrosion, disassemble them, it may be difficult to remove screws, heat torch and pb blaster and patience, brush the corrosion down to bare alu and I would recommend that when you install the hardware you do it with some plastic sheets that they sell some mast makers, they are cut with scissors and you only have to put teff gel on the screws back, if you have deep pitting, once the alu is clean ,you can use epoxy putty and then the plastic plate on top once the epoxy is dry and you have it sanded .

Now if what you want is to remove all the anodizing from the mast to repair deep pitting spots, I tell you that it is hard work, orbital sander and sweat, once the anodizing is gone, treat the corrosion and that's it, maybe paint it?

I paste a pic where you can see the plastic winch pad in white.

[GordMay]

I think neilpride is right.
None of the acid/caustic solutions [NaOH, KOH, CrO3 + H3PO4, or Hcl, etc], commonly used to strip anodizing from small parts, will be practical [nor effective] on a mast; leaving you with a miserable grinding & sanding job.

[SailingHarmonie]

Another vote to just deal with the spot corrosion. There is no benefit I can see to removing the anodizing.

As for removing the existing corrosion, there is no magic, just wire brush (with a NON-steel brush) or sandpaper depending on the shape you are dealing with.

If you want a cosmetically pretty job, really the only practical alternative is paint. If you are willing to do the grunt work on the prep, and find a yard willing to work with you like that, it is not all that expensive. A good paint just lasts a VERY long time, and does not accelerate corrosion.

[The Yacht Rigger]

One alternative (cheap) solution I've seen that actually seems to hold up in the Florida sun, is to remove the anodizing and sand to a nice even finish, then coat the aluminum with concrete sealer.
It's incredibly slippery, but we have a couple clients that have done it and it seems to hold up for many years without failing/peeling etc.
Of course it's a clear coat, so it won't hide imperfections. To make the rig look really good you'd need to sand off the anodizing, and then hire a good spray guy to spray it with high quality two part paint.

[s/v Jedi]

Agree to not remove anodizing, which is the primary protection against corrosion.

Epoxy for repairing pitting: use original JB Weld, which is a thickened epoxy with aluminium already in it, making it very good for this sort of job.

For plastic: simple and cheap are the Ikea cutting boards but you can also order from McMaster Carr etc. Thin UHMW plastic sheet.

[CharmCityBoater]

I have a kenyon mast and just completed a full strip and paint. A couple of points here:

1. You are assuming it is anodized, what makes you think this? Large masts like this, especially from Kenyon, are typically not anodized, rather, they are protected with Alodine. You can usually tell because the aluminum has a golden glow to it after sanding off the paint. Mine was anodized and is from circa. 1985.

(correction, just saw your boat is 30'. Smaller mast. My mast is large as I have a 43' boat. Maybe it is anodized)

2. The recommendation of plastic sheeting to sit between the larger stainless / aluminum surfaces is good, however, I have seen the plastic fail pretty quickly. It also creates a less than solid barrier between the stainless and aluminum. This created loose rivets and screws that need to be retightened after the plastic has start to fall apart. I have been told a better solution is clear truck bedliner. It is a rubber compound you can spray on a surface. Creates a barrier for dissimilar metal corrosion and lasts longer. Also, less likely to result in loose rivets / screws.

3. After sanding my mast I had considered keeping it in bare aluminum. But because of the corrosion you will be left with areas of darker aluminum and, if you use filler to fill in voids, different color spots where the filler is. As a result, I ended up re-painting. To do it right is not cheap but will result in a long-lasting finish. To do it right:

1. Sand to shiny aluminum
2. fill in unwanted holes / pitting with a combination of threaded aluminum rod and aluminum epoxy designed for aircraft.
3. Sand again
4. Wash several times with comet cleanser and ensure it is 100% clean
5. Use a good dewaxer / surface prep to wipe down mast
6. Apply Alumiprep to prepare for paint
7. Apply Alodine conversion coating
8. Apply a zinc-chromate style primer. I used Alexseal CorSpec 161
9. Apply a primer and sand to prep for topcoat. I used Alexseal 442
10. Apply topcoat. I used Alexseal 501
11. After proper dry times buff and wax to protect paint
12. Use clear truck bedliner to protect stainless parts along with Tef-Gel for rivets and screws.

Congrats, you have a mast that will last another 20+ years.

My $0.02

Thanks

[CharmCityBoater]

One other recommendation... For really hard to remove screws in Aluminum PB Blaster and heat may not work. I tend to shy away from heat on Aluminum anyways as much as I can albeit I still used some heat.

I found that a the most imperative tool is a manual impact driver like the one pictured below. Without this tool I could have never removed some of the screws in my mast. It is invaluable.