Corrosion: How to Protect Marine Electronics (A Practical Guide)

Why saltwater is brutal on electronics

Saltwater contains chloride ions that accelerate oxidation and electrochemical reactions. Even a light salt mist can leave a conductive film on PCBs, displays, and connectors. Over time that film traps moisture, promotes corrosion under components, and creates leakage paths that cause intermittent faults.

Common symptoms

• Random resets or dim/garbled displays

• Sticky or noisy button/encoder inputs

• Green/white “fuzz” at solder joints, connector shells, or shield braids

• Elevated standby current, battery drain, or hot spots

• Intermittent NMEA 2000/CAN data errors

  

Quick inspection checklist (5 minutes after a trip)

• Wipe external surfaces with a damp microfiber cloth → then dry.

• Open connector boots and visually check for moisture or green deposits.

• Look for salt crystals/white haze around display bezels and keypads.

• Sniff for “fishy”/acidic odor (often a sign of galvanic activity).

• Verify cable strain reliefs and gland nuts are snug.

Cleaning: what to do (and what not to do)

Do

1. Rinse first with fresh water (light mist), then dry with a lint-free cloth.

2. For circuit boards and contacts, use 99% isopropyl alcohol and a soft ESD-safe brush; wick off with swabs.

3. Use contact cleaner designed for electronics on connectors and switch gear.

4. Finish with gentle warm air—no heat guns on high.

Avoid

• WD-40 or oily sprays on PCBs (attracts dust, can swell plastics).

• Pressure washers and direct hose jets at bezels or seams.

• Household vinegar on boards (acidic residue).

• Scraping solder joints with hard tools.

Sealing & waterproofing (without overdoing it)

• Connectors: Use IP67/68-rated connectors where possible. Add adhesive-lined heat-shrink over splices and backshells. A thin film of dielectric grease on rubber seals helps exclude moisture (avoid slathering pins).

• Cable glands & pass-throughs: Check O-rings; replace if flattened. Tighten locknuts; back with butyl tape if needed.

• Display bezels/keypads: Inspect for hairline cracks; re-seal with marine-grade silicone (mask edges, minimal bead).

• Desiccant & ventilation: Place desiccant packs in enclosed compartments; consider a small vent or fan to reduce condensation.

Conformal coating (when to use it)

Conformal coating protects PCBs from moisture and salt film—great for exposed boards inside consoles, radar pedestals, or engine spaces.

• Acrylic (AR): Easy to apply/remove; good general protection; rework-friendly.

• Silicone (SR): Excellent moisture/salt resistance; flexible; good near thermal cycling.

• Urethane (UR): Strong chemical resistance (fuel/oil areas); harder to rework.

• Parylene: Best barrier; vapor-deposited; usually a factory process.

Rules of thumb

• Clean thoroughly first; any salt trapped under coating will keep corroding.

• Mask connectors, heatsinks, trimmers, switches before spraying.

• Apply thin, even coats; allow full cure per datasheet.

• Keep a service log of where/when you coated (future repairs will thank you).

Power & bonding basics that prevent corrosion

• Keep battery and alternator voltage within spec; overvoltage accelerates electrolytic damage.

• Ensure DC negative and bonding systems are correctly tied per ABYC practice; stray currents eat metals—and nearby electronics.

• Use tinned marine cable; secure every 12–18″ to limit vibration cracks.

• Separate RF/high-current runs from data lines (NMEA 2000/CAN).

• Add drip loops to every cable entering a box or display.

Storage & off-season routine

• Clean and dry equipment; open covers/compartments to air out.

• Remove or disconnect batteries; store at proper float voltage.

• Add fresh desiccant bags; swap them mid-season.

• If you pull a unit: bag it with desiccant and store indoors.

Troubleshooting tip: Is it corrosion or something else?

• Corrosion → often visual (green/white powder), intermittent, improves after cleaning.

• Overheating → brown board areas, melted plastics, consistent failure.

• Firmware/issues → repeatable symptoms not affected by cleaning.

If cleaning restores function but symptoms return quickly, plan for connector replacement or board-level repair at the next service window.

One-page routine you can print

1. Rinse & dry surfaces → 2) Inspect connectors → 3) Alcohol clean suspect areas → 4) Reseat plugs → 5) Check glands & seals → 6) Log issues for winter service.