Mast paint yes/no?

[Don C L]

While it certainly is true that things that are painted and neat look better, it’s amazing how the things that demand less time, energy and money of you become more beautiful over time

[JPA Cate]

Actually, the bubbling you see is galvanic corrosion. It is that the stainless fittings have interacted with the aluminum, and it's not air bubbles, but aluminium oxides. You, or rather, your friend, needs to clean all that out, to shiny metal. At that point, I would prime with etching primer, and touch up the paint, then re-bed the fittings and re-install. The reason is that the corrosion will continue due to the moisture of the salt air environment. This can be done with the mast in place.

I would not try to sand blast the whole deal without removing everything first.

It's a fair bit of work to sand off LPU paint. But, remove mast from boat. Remove all fittings, then it can be hand sanded. If the two of you do it, make your finishing runs all running the length of the mast, like a train on a track. Then, if you want, you can coat with Tectyl*, a clear finish, which you can sand and touch up. Or you could use clear LPU.
It will look beautiful, but it is a lot of work.

Maybe Don has the right of it, eh?

Ann

*We did this on our previous boat, and the mast just glowed when the sun was out.

[a64pilot]

While it may well be galvanic corrosion, most any kind of paint on aluminum exposed to salt water will eventually fail.
It’s why I passed on a Highfield dinghy, they won’t sell a bare aluminum one, and my opinion is that even powder coat will fail
I would assume most all ‘Bare” masts are anodized, it takes a long tank of course but isn’t hard to do.
Anodizing is best, but alodine is a pretty good prep and corrosion protection for aluminum that’s painted.
I’d at least alodine it if I were to paint.
All Beechcraft used to be alodined, I don’t know now, and Cessna’s were if they were Seaplanes, all Thrush crop dusters every bit of aluminum is alodined, and it does help prevent corrosion, crop dusters operate in a corrosive environment

[Sailing August]

It would be a big and expensive job to step the mast. remove all the hardware, soda blast the aluminum and reverse the process. The owner also has the option to use an aluminum wire wheel to clean the bubbled or damaged paint and spot fixing the paint with a primer and final coat. This this can be done from a bosun's chair. Low cost and the owner will not have to disassemble the boat for aesthetics.
Now if the rig needs changing.....then that is a different story. Blast away.

[noelex 77]

Originally Posted by a64pilot

All Beechcraft used to be alodined, I don’t know now, and Cessna’s were if they were Seaplanes, all Thrush crop dusters every bit of aluminum is alodined, and it does help prevent corrosion, crop dusters operate in a corrosive environment

The various different types of aluminium vary very significantly in their properties.

Aircraft aluminium alloys are very strong and light. One of the seven series of aluminium such as 7075 is commonly used. This is ideal for aircraft, but it will corrode if you just look at look it the wrong way .

Marine aluminium alloys are very different.

[Fore and Aft]

I surveyed a Wharram ten years ago that had its aluminium mast painted by a 4" roller with Dulux epoxy metal paint. They were meticulous in the preperation and virtually finished sanding the mast bare then applying the paint on the same day. That mast has now lost all its gloss but still looks fairly good. It might not be perfect but the results verse cost were pretty good I thought.
https://www.bunnings.com.au/dulux-1l...paint_p1400572
Cheers

[Chotu]

How are those Dashew FP boats prepared? They seem to have a very bright and attractive looking aluminum that doesn’t corrode.

[Cpt Pat]

Originally Posted by Don C L

My 60 year old mast has never been painted and is fine.

My 57 year old aluminum mast has never been painted, and it's fine as well. It's been sailed and tied up in a salt water environment the entire time.

Once you paint your mast you are committed to repainting it regularly because deteriorating paint looks much worse than normally-aged aluminum. And in my opinion, much worse than a little aluminum oxide on sails.

Cracks and pits? My mast passes the "10 foot test". They can't be seen from 10 feet away.

[Shoalcove]

I have a painted mast. No big problems with paint failure but there are areas that get scratched or chafed. You can touch them up with a compatible paint without having to redo the entire mast. Once the mast is up, it’s pretty hard to spot the fix. I’d be concerned about the surface finish of a painted mast being sandblasted and left bare. To me, it might look worse than a paint touch-up.
If the paint failure is from dissimilar metal contact, I would remove and rebed the fitting.

[a64pilot]

Originally Posted by noelex 77

The various different types of aluminium vary very significantly in their properties.

Aircraft aluminium alloys are very strong and light. One of the seven series of aluminium such as 7075 is commonly used. This is ideal for aircraft, but it will corrode if you just look at look it the wrong way .

Marine aluminium alloys are very different.

7075 is actually not very common, 6061 though is very common in aircraft, and while I’m not certain, I’d bet most masts are 6061 extrusions, probably T6 heat treat level.
6061 takes to zinc chromate conversion very well, which is what the alodine process is.
Alodine both protects and is a very good paint prep as far as adhesion.

[Bill O]

Originally Posted by Don C L

While it certainly is true that things that are painted and neat look better, it’s amazing how the things that demand less time, energy and money of you become more beautiful over time

+1 for Don's comment. Another vote for no paint on the mast unless you want to make it look "yachty".
IMO painting the mast is similar painting aluminum hulls, its not needed and will be an expensive pain to keep up once you go down that road.

Is there anyway to set up a simple yes or no poll for this thread?

Bill O.

[groundtackle]

Originally Posted by a64pilot

7075 is actually not very common, 6061 though is very common in aircraft, and while I’m not certain, I’d bet most masts are 6061 extrusions, probably T6 heat treat level.
6061 takes to zinc chromate conversion very well, which is what the alodine process is.
Alodine both protects and is a very good paint prep as far as adhesion.

a64pilot, actually the aluminum Excel anchor shank is 7075 and a good track record with them now. Folks are using them full time. We were concerned with long term immersion or simply in the environment they would turn into dust but not the case. Like with bare aluminum spars I've had good results with a simple coating of boat wax, keeps them bright and a greasy film protects.
7075 is fun to work with.
Chris

[a64pilot]

In the aircraft world 7075 is thought to be lighter and stronger than 2024 or 6061, but more susceptible to corrosion so it’s not as common as you would think. I assume your not having a problem due to its size? That or Anodizing is why, aircraft parts are not anodized, I believe it changes the metals property is why. I remember a home built helicopter crashing from a component failure, FAA stated it failed due to it being anodized. But in Marine I would say anodized is pretty much required, my mast is and is circa 1987, and shows no corrosion. There was a small amount where it sat in the mast step but not enough to consider removal of a piece of it.
In aircraft most extrusions are 6061 and most sheet metal 2024.
Also Alclad is not uncommon especially sheet metal, Alclad is a process where the metal is covered with a thin layer of pure aluminum to increase corrosion resistance. And it works really well. I have a 1946 Cessna that shows almost no corrosion thankfully.

It’s my understanding that the biggest reason why there are so many more US WWII aircraft still flying is due mostly to the superior metal that was used, most other aircraft rotted away long ago. I think only the US Alclad metal, but I not sure.

[belizesailor]

Originally Posted by slug

Sounds correct for a boat that will be put to sea



Small coastal craft seem to hold up well naked



And with fittings ...for max corrosion protection isolate the dissimilar metals then bed with Sika or 3m to make the joint water proof

...and Tefgel the screws/fastners to isolate from aluminum. I cut isolating pads from plastic packaging and place between the hardware and the mast.

[rbk]

Originally Posted by a64pilot

In the aircraft world 7075 is thought to be lighter and stronger than 2024 or 6061, but more susceptible to corrosion so it’s not as common as you would think. I assume your not having a problem due to its size? That or Anodizing is why, aircraft parts are not anodized, I believe it changes the metals property is why. I remember a home built helicopter crashing from a component failure, FAA stated it failed due to it being anodized. But in Marine I would say anodized is pretty much required, my mast is and is circa 1987, and shows no corrosion. There was a small amount where it sat in the mast step but not enough to consider removal of a piece of it.
In aircraft most extrusions are 6061 and most sheet metal 2024.
Also Alclad is not uncommon especially sheet metal, Alclad is a process where the metal is covered with a thin layer of pure aluminum to increase corrosion resistance. And it works really well. I have a 1946 Cessna that shows almost no corrosion thankfully.

It’s my understanding that the biggest reason why there are so many more US WWII aircraft still flying is due mostly to the superior metal that was used, most other aircraft rotted away long ago. I think only the US Alclad metal, but I not sure.

The anodizing creates an oxide layer almost as hard as stainless steel. I would assume it also makes it brittle and prone to cracking even if just at the surface = aircraft failure?