Rigging is often overlooked or not completely inspected by both prospective buyers or owners of sailboats as well as marine surveyors who rarely if ever go up a mast. Fortunately I have never been involved with a rigging failure and while I have sailed plenty of old boats with old rigging, I’ve never had a mishap but I have gone up masts to check. Whew! I know it can happen and I’ve seen masts bent over a few times from the spreaders on up. Even a major failure is quite rare and if there is a failure it usually means snapping or breaking from the spreaders and above. Often a halyard can be used to support the mast if a stay or shroud has failed. A rule of thumb is to replace standing rigging every 10-15 years but all those cables and tangs and chainplates can be viable for much longer. And they need to be checked too–and while you’re at it, don’t forget lifelines and stanchions.
A stay or shroud spreads the load and anchors the tension into the structure of the boat in different ways. Where the cable lead to the turnbuckle is important but so is below that as well. One big mistake some boat owners make is to wrap the cables in a tight fitting PVC tube. This is a no-no. The cables have to be able to dry out. Best to spray off salt water after sailing and if anything, put the larger rollers of pvc (or even bamboo) around cables instead of the tighter fitting “spaghetti.”
You can get a complete rigging inspection on most sailboats for under a few hundred dollars but it is rarely done while the boat is on the hard but usually while it’s in the water. But on a really old boat, it’s a good idea to also pull the mast and check everything, not just the mast and boom but tangs, spreaders, wiring, masthead instruments and of course the mast step or compression post and support. Is there a wind speed indicator? Radar? Radar reflector? Check the lights of course. All this should be completely checked and replaced if anything is even slightly worn or cracked. This goes for sheaves which will likely need lubrication–as will the mainsail guides up the mast–and with Teflon or a high tech lubricant and not a grease. I’ll bet that wiring is really old inside the mast of an old boat and it may not be baffled but it should be.
Much more can be said about standing rigging and spars but just care for and maintain them and the sails as they are the engines of the boat. Read more about this and do an inspection yourself but hire a professional when buying a boat or every ten years.