Commander 147

[ebb]

Strength at the top of the mast IS a very real problem with our old craft.
Certainly A-338's weathered stick.

EG that jib-block tang that was added by Pearson above the sheeve caused total corrosion from the top of the sleeve box clear to the end of the extrusion, 2 5/8" of nothing. Aluminum eaten away. I was unable to tell if a former owner reattached the fitting is such a way as to cause such extreme destruction, that he might be responsible for, rather than Pearson. It may also be a problem others have, and don't know about.

What is the fix? There are pros and cons on welding. I hear there is a real problem with the welding interface changing the alloy into something weaker, and don't recommend doing it. Also hear that any annealing will come back to its original temper ON ITS OWN. Don't know - but do know it would take an expert with a TIG and $$$ to weld in a new curved over-lapping section. At the moment the top has been cosmetically sculpted closed with LabMetal so that it looks like nothing ever happened. LabMetal is fun to work with, seems to stick well, but is not structural.

I may add a thin glass patch inside the mast to backup the non-repair.
By way of tying the 'sides' of the mast top together across the front, I am adding a curved piece of 16g s.s. over the front and around to the sides. It will attach to good mast metal and around the masthead fitting. Like an eye patch. That outta do it.

I don't understand why that tang had to be added there in such an awkward way.
Can't the jib block be hung from the 'crane' portion of the masthead fitting? What's correct, Jerry?
It's a little tight but with a long narrow shackle it might work.... or a toggle on a pin....haven't worked it out yet.
If you still have the old head fitting, something could be fabricated and bolted between the 'ears' - some rectangular tube maybe? - positioned in a convenient way to hang the jib block. Again haven't experimented.
I have a Ballenger fabricated copy of the cast aluminum crane fitting with spaced double plates across the top and open all the way thru unlike the old one.
Is your advice counter open today?

Noticed the holes you have in your plates for the new sheeves.
It would take a bit of work - but angled 'clips' could be made that have a small stud or toe on one leg
that engage a similarly placed hole in the plate and have the other leg of the clip bent around outside to screw onto the mast.
So once the clip is screwed in, the toe engages the hole in the plate.
Un-screwing would allow moving the clip sideways inward a bit to move it out of the hole. SO, just holes in the plate, easy to remove. Idea in progress!
Don't think this can be done with your current design.
The idea is to create a lock down for that huge slot by finding a way to grip the plates tight to each side of the mast.
Like having columns on either side of the slot.

Aren't we supposed to be able to dangle the boat from the top of the mast? ? ?