Sizing T-terminals

[Newport41]

I'm installing running backstays and a removable forestay. There are t-ball backing plates in the mast already but not for the new forestay. The problem I'm having is sizing the terminals for the backing plates that are already in the mast. I need to order the fittings in so I need to know what dimension I need to measure in the existing backing plates. Also, if anyone has an opinion on using a t-ball for the inner forestay. It will be removable and used for hanking on a storm jib and for stopping the mast form pumping in conjunction with the runners in heavy seas and winds.

[Newport41]

To clarify, the existing backing plates are installed for the running backstays. I just need to know how to size t-ring terminals for the amsteel stays I'll be adding.

[knothead]

I would recommend that you borrow an assortment of terminals from a local rigger, climb up and see which one fits.
You may have to leave a deposit and a promise to utilize his services when the time comes.

[Faster]

We recently renewed our standing rigging and it turned out we had a European standard T fitting (and, of course, matching backing plates). The standard Ts from the rigger were very similar, but though the T inserted OK, the body of the new terminals was larger and we couldn't rotate them down to vertical. We had to file out the plates to create proper clearance for the new fittings.. not a big job but easier as the mast was down at the time.

Our boat was foreign-built.. so you may not have that issue, but it may be something to watch for as you sift through various fittings.

[Newport41]

Thanks for the advice. I figure I can size the forestay one by strength rating and then measure it and find out how they designate the size. I just wanted to order them all at once tomorrow,