There's the possibility of those things happening to any boat, that's why maintenance and inspection are important. I'm not aware of any specific hull weaknesses in that vintage 18 other than the chainplate anchor points and the hull/deck seam near the crossbars, they were built pretty tough tough. Check the hulls and crossbars for cracks and deformation and cracks around the crossbars.

As far as the rigging...change it out every 5 years at least, no matter what. Starting at the anchor pins, and moving up to the mast tang, replace everything in between. Hobie recommends a shorter interval. Of course if you see any damage to any of the wires, replace them. Corrosion starts from the inside of the roller swages and you can't see it until a crack develops at which time the fitting is considerably weakened.

Anchor pins are critical replacement items!!!

Whatever you do, don't buy used rigging off of ebay. There have been a rash of dismastings here locally by people that got a "deal" on rigging. Go to your local Hobie dealer for rigging, it will be considerably less expensive than having it custom built at a rigging shop, and they have all the proper specs at the factory.

Good rigging on the older 18's is probably the most important maintenance item. Like I said before the 18's are pretty tough!!

Hope that helps.