What to do about moisture and mould on board

Moisture and mould are two issues that most boat owners face sooner or later. They often develop unnoticed but can eventually cause unpleasant odours, damaged upholstery, or even structural damage. Fortunately, with the right approach, much of this can be prevented, and you can act quickly when mould does appear.

How do moisture and mould develop on board?

A boat is naturally prone to moisture. Water comes on board after each trip through wet clothing, condensation, or minor leaks. When this moisture cannot evaporate properly, it creates an environment where mould thrives. Limited ventilation or keeping cabins and lockers closed for long periods also encourages moisture build-up.
The result: musty smells, damp surfaces, and over time, visible mould spots on walls, cushions, or wooden parts.

Prevent moisture and mould

Good air circulation is the first step in preventing moisture and mould. Let air flow regularly, for example through open vents or by opening windows from time to time, stagnant air is ideal for mould growth.

Keeping your boat clean and dry is equally important. Dirt and moisture reinforce each other: clean, dry surfaces stay fresh longer. Dry the interior of your boat thoroughly after each trip and remove any standing water from corners, floors, or drains.

Textiles need attention too. Cushions, curtains, and carpets easily absorb moisture. Let them dry completely before storing them to prevent mould formation.

Perform regular checks for leaks, around hatches, windows, and fittings. Even a small opening or worn seal can let in moisture unnoticed and lead to bigger issues later.

TIP: Use moisture absorbers or refillable desiccant bags to control the indoor climate. Place them in strategic areas such as closed lockers or under benches where air circulation is limited.

What if mould appears anyway?

If you notice mould on board, act quickly. The longer you wait, the deeper it settles into surfaces and fabrics. Clean affected areas with a mould remover, mild soap solution, or water mixed with vinegar, and dry thoroughly afterward. Avoid harsh cleaning agents that can damage materials or spread spores.

Then, make sure to fix the underlying moisture problem, otherwise, the mould will soon return. Often, improving ventilation or sealing a small leak is enough.

A fresh, healthy boat starts with good maintenance

Moisture and mould are common problems, but with a bit of attention, they’re easy to prevent. Regular ventilation, cleaning, and inspections make a big difference. This keeps your boat not only fresh and pleasant but also better protected in the long run.

At Indumar, we’re happy to help with practical advice and reliable solutions to keep your pleasure craft in top condition, so you can enjoy a healthy and comfortable environment on board all year round.