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S&S Swan Maintenance - Mast refit
27 January 2019 - 20:50
Join Date: 27 January 2019
Posts: 6

Mast refit

Hello:  I purchased Swan 41/053 recently.  I am interested in refurbishing the mast without painting it and I have found a company in Ontario, Canada that can etch and re-anodize longer lengths but the two part mast will need to be taken apart.  Has anyone done this?  I am assuming that the bolts which secure the two pieces to the internal sleeve may be corroded in place and that the process will be difficult overall.  I am interested if anyone has experience with this process?  Thanks.

27 January 2019 - 21:35
Join Date: 29 January 2007
Posts: 1018

Dear Holmesm,

very interesting to know there is a company which is able to re-anodize the mast, I would be very interested to see detailed images of the final job, and it would be interested to post the entire process on the "maintenance" section of our website.

Yes, you are right, after about 40 years it could be very difficult to get out the bolts, even if with some patience (and heat/cold) this is a possible job. The heat is not good for anodized aluminum of course, but as you are anodizing again the mast I thinkin the end it will not be a problem.

Anyway I know at least an S&S Swan Owner who had the same problem and he decided to cut the internal sleeve, afterwards he had a new one built. That was about 10 years and many tough races ago, the mast is still pefect (he had it sand blasted and subsequently painted white).

Fair winds!

matteo (47/069 Vanessa)

19 September 2019 - 00:29
Join Date: 27 January 2019
Posts: 6

Dear Matteo:  Thank you for the information.  I thought I would provide an update on my mast project.  We got it apart.  It was not straightforward but everything is intact. We have taken everything off of it.  Despite being able to accommodate the lengths, the anodizing facility decided they couldn't accept the job.  They were worried that their tanks may be damaged.  I do not know the extent to which this was possible.  Perhaps they lost interest or it wasn't so lucrative for them.  Anyway, since I no longer have that option, I have to decide whether to paint it or leave it as it is or even refurbish it to bare aluminum.  Has anyone maintained a bare aluminum mast (without any anodizing)?  The boat will only sail in fresh water for the next decade or more and likely the mast will come down each year for inside storage so I worry that any paint will be damaged in the process.  With the mast coming down regularly, I could keep it polished.  The other option is powder coating.  A local company does painting for the navy and has confidence in their process.  I would be happy to hear any advice on the matter.  Thanks again!  Matthew

19 September 2019 - 17:24
Join Date: 02 January 2008
Posts: 1547

Dear Matthew

When aluminum is ground or machined in air, within a few seconds a thin protective oxide layer forms on the surface, and after a few weeks the thickness has grown to about 0.03 my (0.00012 mil). In hot and moist conditions the oxide layer thickness slowly grows to about 0.02 my (0.008 mil) This would give sufficient corrosion protection in a clean lake environment.
If your yacht is in an urban atmosphere better corrosion protection is recommended, and this can be achieved with boiling water or steam treatment. The water needs to be ion-exchanged though, and steam at 150 C (300 F) speeds up the procedure. A few hours of such treatment increases the corrosion resistance about 20 times. The resulting oxide layer should preferably be close to 1 my thick.
As a comparison it could be mentioned that anodizing produces a much thicker oxide layer. Nautor used to anodize to 25 my thickness.
Powder coating includes oven curing at very high temperatures. Your mast tube is of an alloy tempered to T-6, and it must be made sure that the powder coating curing does not soften the mast temper.
Kind regards

20 September 2019 - 02:59
Join Date: 27 January 2019
Posts: 6

Dear Lars:  

Thank you for this informative reply.  Ideally I would just keep the mast anodized as it has been all of these years.  Alas, some corrosion is apparent over much of the surface of the mast.  Structurally speaking it is sound but it is unsightly and the spar company here will be doing some other welding work which will take those areas down to bare metal.  The corrosion is very superficial but enough that its appearance no longer meets an S&S Swan's standard in my opinion.  I understood that if taken down to bare metal, it would immediately oxidize, just more thinly.  I really appreciate your quantifying the process as it gives me a much better perspective on it and the relative levels of protection.  Since I already have the mast taken apart, maybe I will see if Charleston can re-anodize it. 


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