Corrosion on boomkicker

[markbl]

I have bought a Beneteau Oceanis 361 from 1999 last year and found massive corrosion on the boomkicker. Does anyone have a similar issue?
I assume that corrocion is galvanic and maybe related to the spring inside the Aluminium tube. Any idea how to fix it? The risk if it breakes should be pretty low as I hav a dirk anyway.

Thanks for your response.
Markus

 

[Davidasailor26]

Do you have any pictures of what part is affected? I presume it’s an aluminum tube with cast ends and sheaves? Depending on where the corrosion is it might be possible to polishing it out.

 

[dlochner]

The deep pitting is a concern. This is not surface corrosion that can be polished out. The depth of the pitting probably compromises the strength of the tube. Contact the manufacturer to see about a replacement part. It may also be possible to have a machine shop make a new tube. If not, then a new vang is in your future.

 

[jssailem]

Sure, that is not going to buff out.

While the spring inside may or may not be involved, I suspect there has been some external damage that then proceeded to corrode once the anodized surface of the tube had been dinged. Thinking a snap shackle on a halyard or other b=piecce of running gear flying about on a windy day might do a number on the exposed metal.

 

[dlochner]

It is probably police corrosion due to trapped water. The outer tube may have a sleeve or some kind of bushing which trapped the water. It became acidic and the corrosion began.

Editorial: Island Lady Fire Analyzed – Feature: Understanding and Preventing Aluminum Corrosion | Steve D'Antonio Marine Consulting

stevedmarineconsulting.com

 

[Ted]

There appears to be a slight bulge in the tube at the upper most point of the corrosion. I wonder it there is a part inside the tube that may be causing a problem related to dissimilar metals.

 

[dlochner]

There appears to be a slight bulge in the tube at the upper most point of the corrosion. I wonder it there is a part inside the tube that may be causing a problem related to dissimilar metals.

Good catch. Could have something to do with anchoring the spring inside the tube. What ever the cause, the tube is toast, at least in this application.

 

[Joe]

Is it working? Does the tube slide easily. It looks upside down, small tube on top where water can collect at the insertion point. Where is the contol line's cleat? It should be at the bottom, mast end, or run aft from there so you can control from the cockpit. Large tube above the small one. I don't think it's gonna break, even if there was a hole in the tube. Take it off and inspect it at a workbench if you want to see what's inside. Also try to find any ID on the vang. Or take a full size picture so we can I.D. it. It kinda looks like my Garhaurer rigid vang. Pretty simple piece of kit. couple of tubes a spring and rope tackle.
But heck, if it's still working, either keep using it, or take it apart for inspection. Replacing a tube, if needed, should be easy. Drill out a few rivets would do it.

 

[Davidasailor26]

For a Beneteau I’m guessing it’s a U.S. Spars mast and vang? If so parts information is available at Vangs

From their diagram it looks like the inner tube holds the compression of the spring, while the outer tube is just there to hold everything in line. Unfortunately from the picture it looks like the corrosion and potential bulge are on the more loaded inner tube.

 

[dLj]

It does not look like poultice corrosion to me, unless it's inside out corrosion. See the definition from the NACE Corrosion Terminology:

deposit corrosion—localized corrosion under or around a deposit or collection of material on a metal surface. [also called poultice corrosion] [See also crevice corrosion.]

I'd suggest you take this apart and take a look at the inside. The bulging observed is likely indicative of an internal corrosion process that may be further advanced than what you are observing here on the outside. You are going to have to take this apart to fix it anyway - if you want to fix it...

dj

 

[markbl]

Thanks for all your interesting answers. I will be in Greece at the boat Mid May and will post more infos afterwards.

 

[Barnacle Bill]

First of all, that is not a Boom Kicker. It is a rigid vang, but I can't identify the manufacturer. By calling it the wrong name, you are suggesting that Boom Kickers have corrosion problems and the best to my knowledge they don't. I know the creator of the Boom Kicker and am familiar with their product. They don't even have aluminum tubes like in your picture.