Independent guide: Visual checks cannot prove a component is sound. When in doubt, have a rigger inspect it.

Quick answer

Stainless steel resists corrosion because a thin oxide film protects it, and that film needs oxygen. Where oxygen is starved — inside swages, chainplate slots, under tape and in tight joints — corrosion can attack unseen. Surface tea staining is usually cosmetic; rust weeping from within a fitting, pitting and cracks are not.

Types of corrosion

Type What it looks like Significance
Tea staining Light brown surface film Usually cosmetic; clean and monitor
Pitting Small dark pits Can undercut strength in thin sections
Crevice corrosion Rust weeping from joints, swages, deck slots Hidden attack; often serious
Stress-corrosion cracking Fine cracks, often lengthways in swages Replace immediately
Galvanic corrosion White powder on aluminium near stainless Attacks the aluminium mast or fitting

Where to look

  • the neck of every swage — see swaging
  • chainplates where they pass through the deck — see chainplate replacement
  • under tape and spreader boots
  • tangs and fasteners on the mast

Australian conditions

Warm tropical water and humidity in Queensland and the Northern Territory accelerate crevice corrosion. Boats that sit for long periods also suffer more than boats sailed regularly and rinsed.

Frequently asked questions

Is rust on my rigging dangerous?

Light surface tea staining on stainless is common and not necessarily a structural problem. Rust weeping from inside a swage, a chainplate slot or a fitting, pitting, or any crack is a warning sign that the component should be inspected by a rigger and usually replaced.