Mold and Mildew

"Mold" and "mildew" are closely related—they're both fungi—but in everyday use people are usually describing different behaviors and problems.

Mold vs. Mildew — Practical Differences

Mildew

• Usually flat, thin, and powdery
• Colors: white, gray, sometimes light yellow
• Grows on surfaces (vinyl, fabric, painted wood, shower walls)
• Easier to remove
• Common on boats in cushions, headliners, and lockers

Mold

• Typically fuzzy, raised, or slimy
• Colors: black, green, blue, even orange
• Can penetrate materials (wood, drywall, fabrics)
• Harder to remove and more damaging
• Can produce stronger odors and more health concerns

In short: mildew is usually a surface nuisance, mold is more invasive and destructive.

Why Boats Get Both

The perfect environment for fungi:

• Warm air
• High humidity
• Limited airflow
• Salt + organic dust (food for fungi)

How to Get Rid of Them

1. Kill and remove what's there
   • Hard surfaces (fiberglass, plastic, sealed wood): white vinegar (straight or diluted) or a mild bleach solution (about 1:10 bleach:water); let sit 10–15 minutes, then scrub and wipe clean.
   • Fabrics and cushions: vinegar or specialized marine mildew cleaners; avoid soaking foam cores; sun-dry thoroughly if possible (UV helps kill spores).
   • Wood: light mold — vinegar and scrub; deep mold — may require sanding and resealing.
   • ⚠️ Never mix bleach and ammonia-based cleaners.
2. Dry everything completely — if you skip this, it all comes back.
   • Open lockers and compartments
   • Run fans if available
   • Use a small dehumidifier on shore power if possible
   • Sun and airflow are your best allies
3. Prevent it from coming back — this matters more than cleaning.
   • Ventilation: keep air moving (solar vents, cracked hatches, dorades); avoid sealed, stagnant spaces.
   • Moisture control: desiccants (like DampRid) in lockers; dehumidifier when on shore power.
   • Reduce food sources: clean surfaces (salt + grime feed growth); wash fabrics periodically.
   • Air circulation trick: leave locker doors and cushions slightly open when you leave the boat.

What Actually Works Best on a Sailboat

• Daily driver: ventilation + cracked hatch
• Best upgrade: solar vent or dorade box
• Low-tech add-on: moisture absorbers in enclosed spaces

Quick Rule of Thumb

• Wipes off easily → mildew
• Stains, smells strong, or keeps coming back → mold