Cracked Mast at Spreader

[Endeavour]

I have a Isomat NG105 mast which is 61' long with a 7x11 cross section. There is a crack at the starboard aft end of the spreader base along where it was welded. I was planning to sleeve it with another section of an NG 105.
Today I was told I should grind off the old bases, put "Doubler Plates" about 6' long on the exterior, using a taper, fasteners and adhesive. Then replacing the bases and spreaders. This mast is one continuous extrusion and I hate to cut it if it can be avoided. Will this work? I will be sailing from Hawaii to San Francisco this summer. Does anyone have any ideas or recommendations?

[Brion Toss]

Hello,
First, the mast is already compromised by that crack, so is no longer exactly a continuous extrusion. The question is, how can you restore it?
If I am thinking of the same mast, the spreader bases are not flush with the mast, and they also take shroud loads, with stemball sockets built into the casting; not clear on how you could hope to double this one, except internally, and that would be a neat trick, but would provide strength too far away from that failing metal adjacent to the weld. So I like the grind-it-flush-and-start-over option. Lots of overlap, no stress risers, fasteners as well as adhesive -- it'll be stronger than new. Wouldn't hurt to drill-stop that crack first. And maybe six feet is more than you need.
Once the doublers are on, consider going with a saner configuration, with spreader brackets or through-mast spreader tenon, independent of conventional external tangs. The original configuration was a mass-production convenience, not the best way to do the two jobs. There's a reason they don't make them that way any more...
Fair leads,
Brion Toss

[Dutchman]

Hi, I have an Isomat NG-31 Mast with the welded on spreader roots with stemball and no through bolt also. The crack is small and i wish to fix it before it deforms. There are parts from Rig-Rite with aluminium doubler plates that fit a "through-mast spreader tenon" with stemball.

Doubler Plate for BF-3 SS Spreader Bar:

SS Spreader Bar for BF-3 Spreader:

Would this work?


omegaklubben Norway