What’s That Smell?
The Science Behind Mold Odors on Boats – and How to Prevent Them

“My boat stinks!”
That’s the first thing a boat owner from the Gulf Coast said to us when she stopped by our booth at the 2022 Fort Lauderdale International Boat Show. She was interested in learning how the RiteAire Marine™ Whole-Boat Dehumidification system could cure her boat of its unfortunate smell.
Dank, musty odors in boat interiors are a common problem, especially in humid areas like Florida and along the Gulf Coast. “Boat funk” is what one service manager we’ve worked with calls it. There are a number of causes for bad odors on boats, but one of the most common – and difficult to eradicate – is mold.
Mold growing on board a boat releases microbial volatile organic compounds (mVOCs) into the air. MVOCs can have strong, unpleasant aromas, and, according to the U.S. Environmental Protection Agency (EPA), “…they can be the source of the ‘moldy odor’ or musty smell frequently associated with mold growth.”
Mold gradually destroys whatever it grows on. While this can be beneficial in nature, where mold breaks down dead organic matter like fallen trees, it can ruin a boat’s furniture, soft goods, wallcoverings and overhead panels. Mold also can cause health problems. It produces allergens, irritants and mycotoxins, which are potentially toxic to humans. Sensitive individuals frequently have allergic reactions to mold with symptoms such as sneezing, a runny nose, red eyes and/or a skin rash. Mold also can cause people to have asthma attacks.
While they are not as well researched, MVOCs also can have adverse health effects. The EPA says, “…exposure to mVOCs has been linked to symptoms such as headaches, nasal irritation, dizziness, fatigue, and nausea.”
Mold reproduces in the form of spores that are so tiny they are invisible to the human eye. Mold spores float through the air and are commonly found in indoor as well as outdoor areas, although they only start to grow when they land on surfaces that are damp or wet. According to the EPA’s A Brief Guide to Moisture and Your Home, “There are many types of mold, and none of them will grow without water or moisture.”
Mold can be remediated or cleaned up, but it’s impossible to eliminate all the mold spores from the air. If damp surfaces remain in a boat’s interior, after the remediation takes place, mold is likely to start growing on them again.
The EPA states:

Humidity is a major cause of moisture in boat interiors, in the form of condensation and dampness. Often, humidity-induced moisture occurs in hidden places like inside overhead panels. The best way to prevent mold growth and the odors it emits inside boats is to reduce humidity on board.
The EPA says, “If possible, keep indoor humidity below 60 percent (ideally between 30 and 50
percent) relative humidity.” This is the humidity Healthy Zone that the RiteAire Marine™ Whole-Boat Dehumidification System maintains in yacht interiors. Simply set it at 45RH and the RiteAire Marine system automatically keeps the boat free of mold and its odors.
In fact, RiteAire Marine not only eliminates mold odors in boats, but by reducing humidity on board, the system also can help to reduce other bad smells in boats such as those caused by diesel exhaust and marine sanitation systems. “Humidity traps odor, causing it to travel farther and linger longer,” states Dr. Laura Haupert, Ph.D., OMI Industries chief scientific officer.
With RiteAire Marine, every time you walk into a boat’s cabin, it will smell fresh and clean.