mast repair

[mikee33]

I have a stout mast morgan38, the innershrouds where they attach below the spreaders are on extended bolts , a small mast step is below the attachment point, and too close to allow clearance without the extended bolt. Instead of removing the misplaced mast step which is completely useless, a longer bolt was placed thus extending the attachment tangs outboard of the mast an inch or two.. well it seems i overtightened the stay upon recommissioning and now i have a bolt that has pulled down through the aluminum on one side.extending the hole an extra inch or two.. so now where do i go? i have read other threads about welding and seems that may not be the best route? Any help or references are appreciated....mike

[Brion Toss]

Hello,
First, it should be just about impossible to tear a hole in the mast by "overtightening" the shrouds, even with the extra leverage provided by extending the bolts; it is likely that there was insufficient bearing surface/strength at the mast to begin with.
Next, it is amazing that the tear extended an inch or two. Wow. And welding would not, as you noted, be helpful.
Instead, consider fairing the edges of the tear, and then screwing a layer of aluminum over the damaged area. Make it a big thing, with a goodly number of screws to hold it. You should probably move the hole down to the bottom of the tear on both sides. Drill for the new tang, but get the kind with massive bushings and/or internal reinforcement.
And of course, get rid of that useless step.
Fair leads,
Brion Toss

[mikee33]

in reviewing your suggestion i am thinking of a patch.. with a plug to reestablish horizontal ness..is there a particular alloy or gauge of aluminum i should seek for this? am also thinking should i bed with 5200 ? am assuming stainless screws.. would 5200 help slow electrolysis there also? thanks for availing yourself to us average boaters..

[Brion Toss]

Hi again,
Any spar alloy will be fine. Avoid "aircraft" aluminum. Bushings' walls should be at least 1/8" thick. And never, I repeat never use 5200 for this kind of job, nor most other jobs. A little UHMW tape or similar will serve to isolate the doubler from the mast. Fasten with a multitude of flathead machine screws, all bedded with Tef-Gel. Be sure the bushing picks up mast well as well as doubler. Ideally drilling for the bushing will get you to sound metal.
Fair leads,
Brion Toss

[mikee33]

a neighbor sugested aluminum rivets over ss.screws.. do u have a preference? alum is more compatible with the mast., rivets less likely ot work loose.. i wonder about the strenght tho.. i see many two part masts appear to be riveted. i took some photos, grinded off the lip formed, feel like am ready to fabricate a doubler n bushing..now to find a piece of spar aluminum... thanks much for yr words of wisdom..

[mikee33]

with the weld broken on the cmpression tube its not doing its job..th doubler would have to cover the tube end.. would this b adequate?..do i still avoid welding?

[Brion Toss]

Hello,
First, rivets are stronger in shear than in tension, so if there's a place for them, it could be here. But screws, properly isolated, are better still. As for the compression tube and its weld, just ignore it; with a proper length on the bolt thread you don't need a compression tube. Instead, get tang bushings, and drill to suit. The idea is to get a bearing on more wall molecules with a larger hole.
Fair leads,
Brion Toss

[mikee33]

am not sure what you mean by a tang bushing..found flange bushing..

[Bob Pingel]

Brion is speaking of a flange bushing set into the mast where the tang attaches. An ideal setup is to have a large aluminum flange bushing in the mast, and a stainless steel flange bushing that fits perfectly into the aluminum one, the tang fits between and rides on that stainless bushing. The hole in the SS bushing will accept stainless tang bolt that hold the whole sandwich together.

Brion mentions skipping the compression tube if you get a bolt cut to perfect thread length -- the idea here is that is the threads are perfect length it is impossible to compress the extrusion. An important side benefit is that you will not have load riding on the threads of the bolt - the threads are the weakest part.

This system allows the tang to rotate -- eliminating possibilities of fracture.

This simplest way to pull this off is to purchase a system ready to go. Brion's shop can fix you up.

Bob

[mikee33]

hey guys am back.. am backing up a bit to where Brion sugested moving through-bolt hole to sound metal..am taking short cut or avoiding drilling another big hole in mast.;if i just lower one side and not the other will that be a problem? also what do i do with the unused hole or holes? fill them with epoxy? make a plug of sorts? thanks so much