18-8, 304, 316, 1x19, 7x19, 7x7 - What do all the numbers mean?
How often should I replace my standing rigging?
What maintenance does standing rigging require?
Stainless steel is an alloy that contains at least 50% iron and 10% chromium. The chromium inhibits corrosion - the more chromium, the more corrosion resistance up to a maximum of about 30%.
Type 304 stainless is widely used for rigging, fasteners, and fittings. Most of the stainless produced today is type 304, also called 18-8 because it's made of 18% chromium and 8% nickel. By adding more nickel and 2% molybdenum to 304 stainless, you get Type 316, which has the best corrosion resistance among standard stainless steels. It resists pitting and corrosion by most chemicals, and is particularly resistant to saltwater corrosion.
When stainless steel is produced, the chromium forms an outer oxide layer. As long as that layer remains intact, the stainless remains passive. To prevent corrosion, the passivated stainless steel is immersed in a heated bath of phosphates and salts. This solution forms an oxide film that seals off the iron, preventing it from going into solution in water. Once the oxide layer begins to break down, the stainless steel becomes active and its corrosion resistance is reduced. Rust is the visible evidence of corrosive activity. (2007 Port Supply catalog, p.1090)
The lifespan of standing rigging on the Upper Chesapeake Bay is 10-15 years. Keep in mind that even when you're not sailing your boat, as long as the mast is up, the rigging is under load and the "lifespan clock" is ticking. We recommend leaving wire, swages, and turnbuckles uncovered (no tape, turnbuckle boots, or wire covers), and taking a close look at your rigging annually to check for cracks, broken wire strands, and heavy rust. A crack can be hard to spot (often no bigger than a strand of hair) - a magnifying glass will help.
The best maintenance is prevention. Rinse your boat, including the rigging at deck level, after sailing. Check your rigging on an annual basis for signs of stress and aging. Plan ahead for your next re-rig and do it BEFORE things start to fail. You'll be making a worthwhile investment in your boat and in your continued enjoyment of sailing.
If you'd like a quote on replacing your standing rigging, please give us a call - (410)441-1913 or send e-mail to: firstname.lastname@example.org.