Author Topic: Mast corrosion  (Read 10184 times)

Now or Never!

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Mast corrosion
« on: November 28, 2011, 09:54:04 PM »
We were on our way south from Brunswick, GA, close hauled in a 10-12 knot wind, just a bit after sunrise and somewhere off of Cape Canaveral.  THUD!  What the devil was that?  A quick look around and I decided that it was a "boat noise."  Later, going below to use the head, I noticed that the bilge cover between the mast and the head bulkhead was askew.  I've monitored the corrosion at the base of the mast, but apparently failed to notice how advanced it had become.  The bottom of the mast had moved forward a good inch!  So,drop the sails,  a few more hours to Ft Pierce, FL.  Tomorrow we will have the stick pulled, I will cut off the corroded section and shim up the step with starboard.  I will put a zinc at the base of the mast.

Libations Too

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Re: Mast corrosion
« Reply #1 on: November 29, 2011, 11:21:46 AM »
I have heard of similar corrosion problems and similar approaches to repairs in the past, though I have not heard of attaching a zinc. Is the Starboard strong enough to withstand the compressive forces of the rigging and the weight of the mast? I did not think such materials were sufficiently strong for such uses; when I have worked with it it was very easy to cut and shape...didn't strike me as suitable for structural repairs. Most of the other mast step repairs that I have heard of utilized a fiberglass block (or something similar) to support the shortened mast.

Good luck!
Richard

selene

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Re: Mast corrosion
« Reply #2 on: November 29, 2011, 06:56:05 PM »
Bad luck with your corrosion problem.

I agree - I don't think Starboard is the right material to use (however, I am no expert!) It seems way too soft to me.

Aluminium, or (preferably) stainless steel would be good. There will be a significant compressive force on the chosen material.

Dolce_Vita

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Re: Mast corrosion
« Reply #3 on: November 30, 2011, 01:32:35 PM »
... Aluminium, or (preferably) stainless steel would be good. ...

Do not use stainless! 

Although a stainless step wont rust, the two dissimilar metals in contact (aluminum mast and stainless step) will guarantee that you will have galvanic corrosion of the butt of the mast all over again!  Use aluminum or some non-conductive material that's strong enough.
@(^.^)@  Ed
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with rebuilt Atomic-4

selene

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Re: Mast corrosion
« Reply #4 on: December 01, 2011, 12:36:08 PM »
Ed, you are (of course) quite correct.  Stainless is not ideal but it is done with a suitable insulator between the mast and block. Starboard worse, however!  Incidentally, I don't appear to have a weep hole on the base of my mast.  Does anybody else?

Now or Never!

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Re: Mast corrosion
« Reply #5 on: December 02, 2011, 06:48:39 AM »
The issue of what to use as shims became moot.  The original step was so badly corroded that it was unusable.  So, the welding shop at the boat yard is making a new step out of aluminum.  I hope to re-step the mast today.  Will post pix as soon as I get a faster net connection.

Dolce_Vita

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Re: Mast corrosion
« Reply #6 on: December 02, 2011, 03:12:21 PM »
... The original step was so badly corroded that it was unusable. ...

I'm not surprised.  When the surveyor looked at ours, in a masterful understatement he said
"This will resist removal."
@(^.^)@  Ed
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Now or Never!

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Re: Mast corrosion
« Reply #7 on: December 03, 2011, 05:13:05 PM »
Removal of the mast and the original step was a piece of cake.  Likewise re-stepping the mast.  Here are pix of the mast bottom, orig step and new step.



Mast bottom



Original step



New step

selene

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Re: Mast corrosion
« Reply #8 on: December 03, 2011, 09:41:14 PM »
Wow - looks like a nice job (and definitely needed!!).  Thanks for posting the pics - good reference for the future.

Rusty Pelican

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Re: Mast corrosion
« Reply #9 on: December 07, 2011, 01:59:03 PM »
How is the mast step attached to the keel? I see the four bolts/screws
Are these screwed through the glass into the lead keel?
I looks to me that my heads are rusted and will snap off.
Any problem removing the step?

Thanks

Now or Never!

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Re: Mast corrosion
« Reply #10 on: December 07, 2011, 10:40:22 PM »
The step is attached to the keel with four stainless steel lag screws  2 1/2 inch by 3/8 I think.  They came out easily and were entirely intact in spite of the corrosion of the step. 

roadrunnersid

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Re: Mast corrosion
« Reply #11 on: December 07, 2011, 11:17:42 PM »
« Last Edit: December 07, 2011, 11:45:19 PM by roadrunnersid »

ARICHE

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Re: Mast corrosion
« Reply #12 on: December 11, 2011, 12:43:09 AM »
Hi guys.  I pulled my mast after the second season with ARICHE and had to cut two inches of mast off the bottom.  I then had a friend build a new step out of aircraft aluminum.  I bolstered with hard yellow plastic and replaced the three lag bolts with ones that were three and half inches longer.  I did that in 2008.  Not a bit of corrosion since. If anyone wants the name of the tool company in Ct. let me know
  You will have to send him the steel one and he will fabricate a new one for you.  The price will be between him and you.
Good luck.