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-   -   Do I need to protect areas scratched on mast? (http://www.sailnet.com/forums/gear-maintenance/93428-do-i-need-protect-areas-scratched-mast.html)

marcberoz 10-24-2012 10:07 AM

Do I need to protect areas scratched on mast?
 
Hello,
I have a new-to-me Compac 19. The previous owner had tightened down the spreader sockets on the mast too tight. His work left this dimple:
http://i1062.photobucket.com/albums/...psd28de672.jpg
http://i1062.photobucket.com/albums/...psd288d108.jpg
What I've done is taped off the dimple and filled it with JB Weld. I'm now sanding the JB Weld so it is fair with the adjacent surfaces. The sanding has abraded the aluminum in a spot or two. Do I need to coat the aluminum in these places with some product to protect the mast from weathering/corrosion?
Thanks for your help.
Marc

rugosa 10-24-2012 10:36 AM

Re: Do I need to protect areas scratched on mast?
 
You should insert an aluminum compression tube through the mast. You can get a tube to fit diameter of through-bolt, drill mast to match OD of tube, have it welded in. Tube length should be same as original outside mast dimension. JB Weld will bring spar back to fair but will not address the compression. Without you are facing spar failure. Scratches can be painted with aluminum compatible paint (zinc chromate primer first), or a clear lacquer. We try to wax entire spar annually too.

BTW - is that a weld further up the spar? Might indicate a previous failure or repair.

marcberoz 10-24-2012 11:42 AM

Re: Do I need to protect areas scratched on mast?
 
No that's not a weld. Just some cellophane wrapped around the mast. As far as a compression tube, I was planning to use a nylon bushing. Drill one of the holes wide enough to accommodate the outside diameter of the bushing. The other end of the bushing would press against the inside wall of the mast. The bushing would allow me to tighten the bolt and nut. The spreader sockets would put load against the bushing and not the mast. All I need to do is have the bolt and its nut snug so that the spreader sockets don't wiggle about too much.

Thanks for info about the paint.
Marc

rugosa 10-24-2012 12:57 PM

Re: Do I need to protect areas scratched on mast?
 
Quote:

Originally Posted by marcberoz (Post 937949)
No that's not a weld. Just some cellophane wrapped around the mast. As far as a compression tube, I was planning to use a nylon bushing. Drill one of the holes wide enough to accommodate the outside diameter of the bushing. The other end of the bushing would press against the inside wall of the mast. The bushing would allow me to tighten the bolt and nut. The spreader sockets would put load against the bushing and not the mast. All I need to do is have the bolt and its nut snug so that the spreader sockets don't wiggle about too much.

Thanks for info about the paint.
Marc

As much as it is a small boat I'd still be careful about compression strength of nylon v aluminium. There is considerable compression load at rest and especially from windward under sail. Depending on spreader bases you might be able to bore them out, install aluminum (or stainless) compression tube with threaded ends (I'm thinking something like Navtang used on rod rigging) that will clamp spreader bases against mast and also address compression load from spreader. Check SN forums for older advise on same subject or consult a rigger. Masts are expensive to replace, especially if you have secondary damage to deck, boat, sails, crew.

Stumble 10-24-2012 03:06 PM

Re: Do I need to protect areas scratched on mast?
 
Marc,

The scratches are a non-issue.

The dimple is a potentially catastrophic one. Fairing it with JB weld is at best a cosmetic fix to a structual problem. It needs to be brought back to true, then a standard compression tube added. Nylon is not acceptable here, think aluminium or titanium (stainless if you have too).

marcberoz 10-24-2012 07:22 PM

Re: Do I need to protect areas scratched on mast?
 
OK. You've convinced me to use a metal compression tube rather than nylon. I'll get more opinions about the mast integrity too.
Marc


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