Z Spar masthead stemball fitting

[ParaHandy]

Not quite masthead. This fitting appears to be a stemball into some sort of stemball cup which is inserted and then, perhaps, twisted to lock it in. I looked at something very similar on a mast taken off and if it wasn't for the beady glare of the rigger in the shop, I'd have had a good fiddle. What scares me is that it appears as though I could quite easily lose the cup inside the mast (I want to replace the rigging without taking the mast down). The one I looked at had a 6mm hole drilled just above it for a rivet (which wasn't and never had been fitted).

The ZSpar mast is 20 years old.

If anyone has replaced this shroud, would they be kind enough to offer advice?

 

[alahol2]

That looks like a classic 'how-not-to' judging from the angle the wire leaves the swage.

 

[Spirit of Glenans]

I have one of these. It's at the top of a removable inner forestay which came (unattached) with my Dufour 30 Classic which had originally belonged to Les Glenans. During the boats time with that organisation, I saw on a number of occasions, instructors returning to the base with this in their hands, as it regularly fell off if not kept under a downward pull while being detached from its stem fitting to be stowed at the shrouds. I will be re-attaching it this year as the mast is down for the first time in four years.
It does have a technical name, although I have heard it generally being referred to as a T-Ball fitting. When re-attaching the cup, you will need to use Duralac Paste, or similar, to isolate the stainless steel from the alloy mast and only use a monel rivet, (also with Duralac), as standard ones corrode in a relatively short time.

 

[Spirit of Glenans]

That looks like a classic 'how-not-to' judging from the angle the wire leaves the swage.

These fittings, AFAIK, are generally used for removable forestays, so this one just might not be under tension .

 

[ParaHandy]

The cup for a T ball fitting is riveted onto the mast with at least 3 rivets. This hasn't got any. I could easily be wrong ...

A T fitting looks like this and I don't think that's what I've got.

http://www.stalok.com/popup.aspx?src=/images/product/large/045_1_.jpg

 

[30boat]

My fittings are the same.You can't lose it inside the mast because the shroud goes through it.The only way to remove the fitting from the shroud is by removing the bottom swage fitting.

 

[Roberto]

My fittings are the same.You can't lose it inside the mast because the shroud goes through it.The only way to remove the fitting from the shroud is by removing the bottom swage fitting.

+1

same as mine, once the termina is swaged, the shell cannot fall away. In other words, the rigger first has to pass the cable through the shell, then swage it.
Rivets are only needed to keep the shell in place when cables are slack, once they are tightened the shell will seat against the mast wall

 

[ParaHandy]

Gentlemen, thank you for that. Could either of you look at this description of what is called a Stemball backing shell tang and confirm that is what you are both describing

http://www.rigrite.com/Spars/SparParts/Tangs-complete/Stemball_Backing_Shell.htm

You remove the fitting etc! Great when you know how. It also confirms something that a ZSpar person told me that you could swage every fitting - up to a point, as in this case the other end is a swaged stud which you could indeed pass through the shell. Has to be so if the swaged stemball can go through.

Many thanks. You've been most helpful.

 

[30boat]

MY mast is also a ZSpars and I have the oval fitting but no rivets http://www.rigrite.com/Spars/SparParts/Tangs-complete/stemball_backing_shell.htm#Oval I did the rigging myself and had no problem inserting the fitting into the hole in the mast.

 

[merlin3688]

Z Spars still do the masts this way but the fitting is slightly better now! Should be a rivet at the top, if you take the fitting out you will see the hole, Monel pop rivet required, only holds the fitting in place when no tension on wires.
http://www.zsparsuk.com/#!masts/c2f6
See this page from Sta Lok, the codes on the stemballs with a Z are in relation to a Z Spar mast. http://www.stalok.com/p-417-swage-stemball.aspx

 

[Spirit of Glenans]

The cup for a T ball fitting is riveted onto the mast with at least 3 rivets. This hasn't got any. I could easily be wrong ...

A T fitting looks like this and I don't think that's what I've got.

http://www.stalok.com/popup.aspx?src=/images/product/large/045_1_.jpg

Only one on mine.

 

[Seajet]

That 'T-Ball 'fitting in the first pic is horrible, absolutely inviting disaster !

As mentioned the pull from the swage ( and that including the whole wire should be replaced pronto ) should be straight.

A stainless protection around the lower edges of the hole would be nice, as long as it's fitted with zinc chromate paste like ' Duralac ' to avoid disimilar metal galvanic corrosion.

I don't understand why the hole & rivet above the slot is mentioned, it should have no relation in context.

It is normal pratice though in rigging and aircraft to drill holes at the corners of square holes to prevent the propagation of cracks in alloy.

 

[30boat]

That 'T-Ball 'fitting in the first pic is horrible, absolutely inviting disaster !

As mentioned the pull from the swage ( and that including the whole wire should be replaced pronto ) should be straight.

A stainless protection around the lower edges of the hole would be nice, as long as it's fitted with zinc chromate paste like ' Duralac ' to avoid disimilar metal galvanic corrosion.

I don't understand why the hole & rivet above the slot is mentioned, it should have no relation in context.

It is normal pratice though in rigging and aircraft to drill holes at the corners of square holes to prevent the propagation of cracks in alloy.

That's not a tball fitting,it's a stem ball fitting and it's not under tension.Probably for a removable stay.Anyway a removable stay fitting should be toggled at the mast so that it is fully articulated.Stemball fittings are not really suitable for this purpose.

 

[Seajet]

I was using ' T-Ball ' as a general description for anything which slots into a mast sideways...

By the authors' description it is under tension, and anyway if it's ever going to be used it needs to have a straight pull; what else is it for, decoration ?!

Toggles at the upper end are unusual, but this stay certainly needs some help - including a new wire and terminals.

 

[Roberto]

Yes it will go through the opening. I have the reference BST8 of your web address, probably the bulkiest model, the maximum horizontal section of the shell, inserted vertically, passes through the opening.

An additional thing:
1. There are two different shell seating shapes (the shape of the stemhead ball and the internal shape of the shell), one is more frequent, the other is Sparcraft. If you replace the shell, (recommended, they are not expensive), buy one where the stemball terminal will seat correctly.
2. Those shells are sometimes coated with a very *very* thin layer of transparent lacquer to avoid corrosion steel/aluminium; it is absolutely invisible but very effective, mine were 20 year old and there was not a sign of corrosion. If you scratch the surface of the shell with a blade you might see some chippings. When I mounted the new ones, I added some isolating compound anyway.

Has the cable in the picture really that orientation, or is it simply because it is slack ? Agree with others, whatever the reason, the angle "cable <-> mast shell" is too un-aligned..

 

[ParaHandy]

I've a feeling that the rivet hole just wasn't drilled. The shroud never comes off unless you fall foul of an insurance survey ....

My shroud is 8mm whereas the Z Spar stemball specials are 7mm. The cup diameter is the same, 26.5mm. I can't quite see why a 7mm wire stemball has been made especially for Z Spars.

Many thanks again for all your help

 

[Spirit of Glenans]

Gentlemen, thank you for that. Could either of you look at this description of what is called a Stemball backing shell tang and confirm that is what you are both describing

http://www.rigrite.com/Spars/SparParts/Tangs-complete/Stemball_Backing_Shell.htm

You remove the fitting etc! Great when you know how. It also confirms something that a ZSpar person told me that you could swage every fitting - up to a point, as in this case the other end is a swaged stud which you could indeed pass through the shell. Has to be so if the swaged stemball can go through.

Many thanks. You've been most helpful.

Yes, that's what I've got. Swaged stud at the bottom into a wheel-type tension adjuster for removable forestay.