Hello,
And condolences on the need to press for replacing that rigging. Obviously you are right, and perhaps even righter than you know. The best testing has been done by Navtec, and you can find things summed up here:
http://www.pcmarinesurveys.com/Riggi...%20service.pdf.
As you will see, rig life is determined by load cycles, climate, amplitude, etc.
Two other things to consider: 1. The jibstay is probably the highest loaded piece of the rig, so maybe -- just maybe -- you've gotten a bit of advance warning on the state of everything else. 2. Quality of wire, of swage, relative wire size, and state of tune can also accelerate rig failure. These are unknown, and you might well be even closer to catastrophe than Navtec's data indicates.
A close and meaningful inspection of the remaining components, including chainplates and mast(s) would be really, really prudent now. If this is a passenger-carrying vessel, we can hope that some of our trainees with the Coast Guard might chime in. Meanwhile, for what it is worth, I will add that, in my personal estimation, anyone who is resisting a comprehensive rig replacement is not thinking clearly.
Fair leads,
Brion Toss