Inspecting Rivets and Screws for Trouble
One of the interesting conclusions from our testing was the surprising strength among all of the test fasteners when loaded in the shear. Even old fasteners, as old as 20 years or more, can continue to offer good service in small spars if maintained reasonably well and engineered with an adequate safety margin.
1. Mast gates are good for threaded fittings, since they will be removed occasionally. Be sure to use an anti-seize coating such as Tef-Gel or Loctite to prevent the screws from seizing.
2. This bent stainless steel strap is not correctly aligned with the load and possibly under specification.
3. Aluminum rivets secure this mainsheet padeye. The fastener itself is under very little load, but corrosion is clearly taking its toll on the fastener head, and more critically, the stem, which is inside the spar, invisible to us.
4. This rivet on the mast of a beach cat spent 25 years at the beach and then 15 years in the backyard covered in leaves. Forty years later, the strap is ugly, but the rivet is sound.