mast repair

[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

[Brion Toss]

Hi again,
Do not, I repeat do not make one side lower than the other. As noted above, install a reinforcing layer over the damaged area. Make it big, to carry the load into lots of sound mast. Drill for the new tang bolts near the bottom of the torn section, but on the extra layer. Capeesh?
Fair leads,
Brion Toss

[mikee33]

yessirr and thanks for your patience with me. as i once again ask for help.It seems like drilling out two more 11/16ths holes plus larger for the inserts will weaken the area.. The doubler will help with that.

[Douglas]

After reading this thread, I decided to make Aluminum Flange Bushings, for the shroud tang bolts on my Forespar mast replacement.

The Forespar mast came with 1/4" X 2" diameter aluminum round disks welded to the outside mast wall with a 5/8" centered hole for the thin wall aluminum compression tube and a 1/2" tang ss through bolt.

I don't have a guideline to choose the outside diameter of the bushing that penetrates the mast wall for a ss 1/2" and or a ss 5/8" through bolt without allowing clearance for a compression tube.

I hope to use 2" outside diameter of the flange,,, which, will provide a wide enough flange apron to counter sink 2 or 3 flat head screws, to secure the flanged bushing to the outside of the mast wall.

I have been thinking that a 1" diameter hole in the mast would be sufficient size to spread the load of a 1/2" or 5/8" through bolt with a bushing to match the 1" mast hole.

Is anyone out there, willing to comment on these sizes or design ideas ?

Douglas

So nice to see that Brion is back on line, good on you mate !

[Bob Pingel]

Douglas-

I don't see a need to attach the flange to the spar with fasteners. The through bolt will hold the tang and bushing in nicely -- if the through bolt fails keeping that bushing in place will be the least of your worries.

I encourage you to checkout the aluminum/stainless bushing sandwich arrangement I described above. You can purchase this entire tang set/bushing arrangement through Brion for a surprising low price.

For reference, I would say the wall thickness in the bushings is 1/8" and the flange width is about 3/16" to 1/4".