Spars: How old is TOO old?

[Dale I]

I have just re-installed the lower halyard sheave bracket into the mast of my '78 C&C 34, (a 50' stick), and noticed that there was a considerable amount of powdery aluminum dust and an orange-peel-feel on the inside of the mast where the stainless steel sheave bracket attached. What is your experience with internal corrosion in spars and at what point does one replace a mast? After failure and the things laying across yer deck? Given that this thing was factory mounted in a slot 1 1/2"x4" that was cut into the aft-located bolt rope track it seems to me that it significantly reduced the strength of the mast section right out of the gate.... Comments are welcome.

 

[Dale I]

Ok now, you Engineer types...

...I need your help. Does anyone know something about the safety factors built into spars? Can you mic the thickness of a mast extrusion and determine the amount of corrosion, (and safety factor), that remains? I believed that my anodized mast was in top condition with no corrosion given the outside appearance...until I pulled the lower S.S. halyard bracket.It seems to me that a keel stepped mast is somewhat analogous to a cantilevered joist and if you were to knotch a joist four feet out from the support on the compression side, (in what would be the extreme fibre, rather than in the neutral axis), and then load it up, (with a backstay adjuster), that you may be looking for trouble when you factor in significant internal corrosion at the worst possible time.... . I'd hate to pitch $5,000 at a new mast if it was little more than surface crud. There has got to be some feeble spars out there and I have not found any means to assess the real condition. Thoughts or input would be appreciated.

 

[Don Evans]

Here is Someone To Ask...

Post your query at Brion Toss's "Spar Talk" discussion forum for some enlightening answers. The "experts there" do this stuff for a living. One of the best sites going for insights on rigging and spars. Good luck.Don

 

[Steve Dion]

Contact Rig Rite.

Dale:Contact the folks at Rig-rite. They have most of the parts for older boats and can probably give you what you need.www.rigrite.com

 

[Dale I]

Thanks all,

Thanks