How to Clean, Protect and Inspect Stainless Steel Boat Hardware

Rinse all stainless with fresh water to dissolve salt. Then wash it with mild boat soap and a soft cloth or brush, and rinse again. Salt holds moisture against the metal, so regular washing prevents most staining. ASSDA notes that just wiping with a damp cloth smears salt around instead of removing it. Dry with a towel to avoid water spots.

Never use steel wool, wire brushes or ordinary scouring pads on stainless. Tiny bits of plain steel get embedded in the surface and rust, leaving new orange spots within days. Use soft cloths, nylon pads or a toothbrush. Clean tools that have touched carbon steel before using them on stainless.

Practical Sailor warns that chlorine cleaners are highly corrosive to stainless. Keep bleach-based cleaners, chloride cleaners and anything containing hydrochloric (muriatic) acid away from stainless fittings, and rinse well if they splash on.

Before using any rust remover, tape off nearby gelcoat, paint and wood, and cover canvas and vinyl. Acids can etch or dull gelcoat, stain fabric and attack aluminum. Work in the shade so products don't dry on the surface.

Apply a stainless or rust-stain cleaner made for boats. Practical Sailor's testing found the most effective rust-stain removers usually contain phosphoric or oxalic acid. It prefers pastes and gels because they're easier to control than runny liquids. Follow the label for dwell time, work it in with a nylon pad or toothbrush (along the grain of brushed finishes), then rinse thoroughly with lots of fresh water. Repeat rather than scrubbing harder.

Polishing makes stainless shiny, but passivating helps it stay that way. A passivating product dissolves free iron from the surface so a fresh, strong oxide layer can form. Practical Sailor tested citric acid-based passivating products and found them effective and much safer than the nitric acid used in industry. Apply the product as directed, let it work for the time on the label, then rinse very thoroughly. Don't leave it on longer than directed or mix your own strong acid. Passivating is especially worth doing on welds and on cut or drilled areas, where rust often starts.

Once clean and rinsed, a stainless metal polish brightens the finish and can leave a light protective film. Rub along the direction of any polish lines. Polishing is cosmetic. Don't let a shine hide pitting or cracks you should be inspecting.

With a flashlight and magnifying glass, check:

• Welds on rails, towers and bimini frames
• Where tubes enter fittings and bases
• Chainplates, stanchion bases, cleats, lifting eyes, ladder mounts, and swaged rigging terminals (sailboats)

Look for pits, hairline cracks, rust weeping from a joint, or swelling. Practical Sailor notes that polishing can wipe away the warning signs of a fitting that's about to fail. Inspect before you polish.

A surveyor's corrosion article for BoatUS adds what to look for: stress cracks in formed fittings (swaged terminals, bent brackets) branch out like a leafless tree and can fail with no other warning, yet you can usually find them with a magnifier; rust on a bow pulpit can start at tiny cracks from flexing; and rust staining on a valve handle is a warning that it may break off when you need to close the valve in an emergency. It also lists stainless swim-platform brackets and ladder bolts rusting because the platform's wood core got soaked through the fastener holes, the same trapped-water problem as step 9.

Rust stains spreading from under the base of a fitting, or from its screws, usually mean crevice corrosion. Water gets trapped under the flange or in the bolt holes, runs out of oxygen, and the stainless turns active and corrodes. BoatTest notes this often happens where hardware was bedded only around the fasteners, not under the whole base. The part you can't see, inside the deck, often looks worse than the part you can. Cruising World says chainplate and padeye bolts are especially at risk. A surveyor writing for BoatUS explains why: most decks have a wood or foam core, and once the sealant around a fitting fails, the wet core holds water against the bolts like a sponge. Those rust blobs under the deck usually mean a leak, not cheap bolts, and a brown "blush" around a fitting's base is more often water getting under it than harmless salt staining.

A fitting that keeps weeping rust needs to come off. Remove it, clean and inspect the base and bolts, and replace any bolts that are pitted, thinned or cracked. Cruising World recommends bedding the entire base in sealant, not just the bolt holes, so water can't collect underneath. It also notes that bedding compounds have a finite life (roughly five to seven years is mentioned). Follow the deck-hardware-rebedding guide. Use 316 fasteners where they're exposed to salt.

Never use plain or zinc-plated steel screws in stainless fittings. They rust and stain everything around them. Practical Sailor also notes that pairing stainless with other metals, or even a different stainless alloy, can cause staining and pitting. When replacing fasteners, match the alloy, and ideally use 316 on deck.

Tape, rubber sleeves and plastic covers on stainless rigging or rails trap moisture against the metal and hide corrosion. Cruising World advises avoiding them where you can. If you must use them, remove them periodically to dry, clean and inspect underneath.

Rinse after every trip, wash weekly in salt water, and repeat the clean and passivate when tea stains come back. Log inspection dates and any fittings you're watching in BoatMend.