Stem ball rigging

[Sea Change]

New to me boat has what I believe are called stem ball fittings for the caps, intermediates, and lowers.
All my previous boats had tangs, so the upper ends of the stays just needed the correct diameter of eye.

How do these stem ball fittings work? And what components ought to be replaced with each re-rig?

 

[vyv_cox]

I have come across them a few times. They are fitted to some expensive blue-water boats and have a good reputation. Googling some suppliers it seems there are no standard sizes, each mast manufacturer selecting specific dimensions. If replacing you need to specify the ones for your mast/boat.

I did a failure job on one that broke but that was on a forestay, almost certainly due to being too slack. The movement of the ball exceeded the dimensions of its socket, causing bending.

 

[Sea Change]

I have come across them a few times. They are fitted to some expensive blue-water boats and have a good reputation. Googling some suppliers it seems there are no standard sizes, each mast manufacturer selecting specific dimensions. If replacing you need to specify the ones for your mast/boat.

I did a failure job on one that broke but that was on a forestay, almost certainly due to being too slack. The movement of the ball exceeded the dimensions of its socket, causing bending.

Thanks Vyv
It appears possible to buy the complete mast fitting, I'll just have to make sure there are no compatibility problems with the ball and socket.
The boat is a 1988 Jeanneau Sun Kiss, if that helps. The boom has the remnants of a Francespar logo on it, so I assume the mast is the same.

 

[Roberto]

All of mine are like that, quite common over here, when I replaced the rigging I replaced also all the shells (coquilles), there are two main standards one is Sparcraft the other sorry can't remember the name, the terminals and the shells have slightly different geometry. The steel shells usually come covered with some transparent lacquer to isolate them from the mast light alloy, though I also added a thin coat of isolating compound, can't hurt. Very easy to fit, just twist a little the shell to insert it into the hole in the mast, twist it again to make it seat then a final small rivet to lock it.
One thing I do not like is in case of cable breakage, it's a lot easier to fit a replacement cable/dyneema with eye terminals (ditto for the top part of the turnbuckle), I had to keep/source a number of additional fittings for my emergency shroud

Post in thread 'Upcycling rigging'

9 Sep 2024

Can anyone here think of useful new purposes for any of it?

I kept some of the mast and deck fittings and pins (one for every different cable size) to make an emergency stay/shroud: it's dyneema rope, one end is already spliced with thimble and will go at the mast with the suitable terminal, the lower dyneema rope end will be eye spliced to the proper length and will be tensioned by two of those Precourt/Colligo black anodized fittings H G and I. I can replace all single elements of the standing rigging.

Also, the central wire of a 1x19 cable is perfectly straight and once bent...

• Roberto

The stemball terminal is fitted inside the shell, then I have an eye nut on its screwed end, to which I attach the dyneema. Should I ever
break something and not dismast

 

[Sea Change]

All of mine are like that, quite common over here, when I replaced the rigging I replaced also all the shells (coquilles), there are two main standards one is Sparcraft the other sorry can't remember the name, the terminals and the shells have slightly different geometry. The steel shells usually come covered with some transparent lacquer to isolate them from the mast light alloy, though I also added a thin coat of isolating compound, can't hurt. Very easy to fit, just twist a little the shell to insert it into the hole in the mast, twist it again to make it seat then a final small rivet to lock it.
One thing I do not like is in case of cable breakage, it's a lot easier to fit a replacement cable/dyneema with eye terminals (ditto for the top part of the turnbuckle), I had to keep/source a number of additional fittings for my emergency shroud

Post in thread 'Upcycling rigging'

9 Sep 2024

Can anyone here think of useful new purposes for any of it?

I kept some of the mast and deck fittings and pins (one for every different cable size) to make an emergency stay/shroud: it's dyneema rope, one end is already spliced with thimble and will go at the mast with the suitable terminal, the lower dyneema rope end will be eye spliced to the proper length and will be tensioned by two of those Precourt/Colligo black anodized fittings H G and I. I can replace all single elements of the standing rigging.

Also, the central wire of a 1x19 cable is perfectly straight and once bent...

• Roberto

The stemball terminal is fitted inside the shell, then I have an eye nut on its screwed end, to which I attach the dyneema. Should I ever
break something and not dismast

Thanks, very comprehensive and helpful.
I can get the terminals from StaLok so I just need to find out which 'shells' are compatible.
I'm inclined to replace the whole lot as the rig is of dubious heritage.

 

[Tranona]

There are least 4 different types of T ball terminals and cups, mostly swaged, although there is a swageless version of the St Lok type. I have T balls on my 1970s Proctor mast and the cups were fine when the rigging was replaced recently. This gives you an idea - the matching cups are on a different page jimmygreen.com/1480-wire-rigging-terminals

 

[vyv_cox]

For interest, I have added to my website a failure report of a stemball eye that I investigated a few years ago.
Stemball forestay fitting failure

 

[Sea Change]

For interest, I have added to my website a failure report of a stemball eye that I investigated a few years ago.
Stemball forestay fitting failure

Thanks. Makes me glad my forestay is on a normal toggle.