Re: 35 year old standing rigging - but rigger says it's ok
There is a good standard for when to replace standing rigging. The issue is that few if any boat owners are willing to follow the standard.
The industry standard is a full disassembly and x-ray inspection when the rigging reaches 7 years old, and continuing x-ray inspections every year after that. This is the recommendation from the manufacturers of the parts, any deviation on this is the owners responsibility. Frankly the cost of doing this is pretty silly, since a full inspection is often close to the same as a re-rig for a small boat. But it is the standard.
As has been mentioned above, there are a number of factors that effect the service life of rigging, and so what may be acceptable on one boat is going to cause a major problem on another.
For instance, temprature is one of the critical factors in if, and at what speed crevice corrosion occurs. 316 stainless for instance doesn't suffer from crevice corrosion if the temprature is below 60F, while 304's critical temprature is 30F. So as long as your boat is never exposed to tempratures above 30F no worries.
Salinity is another issue, the above tempratures are based on the standard assumption for the salinity of oceans, but your local area may be significantly higher or lower. If in a high salinity environment you may have a bigger issue.
But corrosion is one one of the issues. Stainless steel also suffers from work hardening, which means that as the parts are stressed over time it actually becomes stronger. The problem is that at the same time it also becomes much more brittle. So how many load cycles you have on the rigging can be as much an issue as corrosion. This is independent of age, which is why offshore race programs replace their rigging every circumnavigation, or one year, whichever is sooner.
Frankly at 10 years I would replace rigging regardless of condition if I was headed down island, or taking what had been a daysailor for some serious cruising. Figure a few thousand dollars as cheap insurance when contemplating a $50,000 mast and rigging. Not to mention the potential harm that could occur from a rigging coming down mid ocean.