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Mast and Boom Corrosion - how late is too late?

ofshore74

Member III
There's an E-38 I'm looking at that has some obvious corrosion around parts of the boom and mast - guessing this is an issue with dissimilar metals. How late is too late for corrosion? And is redoing the entire mast boom the only option? Something tells me patch work won't be enough and it would need to be done right. I'm also wondering whether this has eaten right through the bottom of the boom but I didn't get close enough photos to tell for sure:

https://drive.google.com/drive/folders/0Bx6tzmnoism-QUc1SU1RR1VicXM?usp=sharing
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
Hard to diagnose from a distance, but it looks like corrosion has gotten under the paint where there was an opening, or where the surface was disturbed by screws or rivets. This is usually fixed by removing the hardware, cleaning the aluminum, and refinishing it with the required layers of prep and surface paint. Then put a good sealant under all of the parts when re-attaching.
Darned salt air really accelerates bimetallic corrosion!

The surveyor will probably poke at the blistered parts to assess if there is any real loss of metal strength. We had some of this corrosion on the lower vang bracket when we bought our boat. I removed the fitting and only one threaded hole was really bad - same fitting as yours or quite similar - it is still doing fine.

Aside: is this a boat we can all look at on the web?

Cheers,
Loren
 

tenders

Innocent Bystander
While some of that business between the vang and the mainsheet attachment point doesn't look great, it doesn't look too bad, and the rest looks like the result of the paint coating failing with barely any aluminum corrosion.

Now, is it failing because of a few issues local to the current points of failure, or will all the spars look like that in a few years?

A really great cosmetic repair will involve stripping the whole spar(s) down to shiny metal, priming, and painting. This feels like a lot of work for the issue we're seeing here.

A partial repair will involve stripping down the corroded areas and feathering the new paint into the old paint. I don't know how well new LP paint adheres to older LP paint, but suspect the repair will be obvious no matter how good a featherer you are.
 

Christian Williams

E381 - Los Angeles
Senior Moderator
Blogs Author
Something tells me patch work won't be enough and it would need to be done right

Nah, patch it and forget it.
:)

This corrosion has been present on every boat I've owned, and it's easier to deal with if the spar is painted or color-anodized than if old clear anodizing (or bare aluminum.)

I just make a neat rectangle of painter's tape around affected parts, sand down to metal, prime and paint. Lately I use Interlux Brightside, but in the past Hardware store spray has lasted for years.

No feathering, just a neat tape edge of glossy (or semi-gloss or flat, whatever matches best). It looks like a design feature.
 

bgary

Advanced Beginner
Blogs Author
^^^ what he said

Most of what is in those pictures is surface corrosion coupled with paint bubbling. Easy to remediate - wire-brush down to bright metal, acid-rinse, prime with a chromate-based primer, and then paint with the rattle-can of your choice. Tape off a nice rectangular work area and have at it.

The only reason to strip and refinish the whole spar (IMO) is for cosmetics, once you have nothing else you need doing and are looking for something to throw money at. In the meantime, the mission is to protect the aluminum against further corrosion, and that can be done on a spot-by-spot basis.

I painted mine with Rustoleum "satin finish" black... http://www.ericsonyachts.org/infoexchange/entry.php?402-Time-is-Fluid-**-(mast-re-hab-part-1-of-3)

$.02
 

Christian Williams

E381 - Los Angeles
Senior Moderator
Blogs Author
Makes a good impression. Asking price rational. Owner probably was attentive.

Cushions, in pix at least, look good, as does the sole (some water damage in the head/shower; the darkened areas; typical)

Ask about engine hours, which got left out. Standard would be 1500-2000.

Ask about age of sails. The description "good condition" usually means the sails need immediate replacement. But maybe not in this case.
 
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ofshore74

Member III
Ask about engine hours, which got left out. Standard would be 1500-2000.

No engine hours available.

Notes on engine: It ran good when we left the dock, although there were some oil leaks that got addressed (loose dipstick, air cleaner removed cleaned and reinstalled, apparently if the oil level is full broker thinks it's clogging the filter with oil, suggests keeping it at fill mark. Also high output alternator made a noticeable sound when motoring, not a bad sound almost like a quiet whirl sound - probably normal but I'm not a mechanic!)

As I said before picked up moisture readings on deck and a number of other things that need to be addressed - all typical for a boat this age I keep hearing.

A marine mechanic to go over the boat first.
 
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