Wet deck...

[Freesail99]

If you have mold inside the boat, that could be one reason. Another could be a leak. Have you checked your bilge ? I suggest installing a solar vent which will keep air moving and aid in keeping the inside a bit dryer. It will also make the cabin a bit cooler, which can't be a bad thing.

[Giulietta]

Everlong if its the mold on the vertical side of the hull, seems like due to perspiration, and boats natural moisture contents.

Wet deck looks different. Its all deformed and such as the core expands due to water ingression.

Mold and sailboats is like women and diamonds.....live with it, and use bleach diluted with water to clean, and go sailing.

Your roof seems ok.

[Boasun]

That kind of mold is usually from poor ventilation and high humidity. Use the product 'X-14' to remove it... Try that product in seldom seen corner first to see how it affects the materials of your boat.
When you secure the boat after being out in it for a weekend or more. Ensure that you have good ventilation and a reduction of humidity inside your boat. A small well secured space heater or a 100W light fixture would help here in reducing the humidity inside your boat. Just ensure that there is a topple switch on that space heater. So if it is knocked over it will be turned off automatically. Fires have been started without that safety feature. Same idea with the light fixture also.
One way of reducing the humidity is make sure that your bilges are dry. Coolers empty and check the ice box also... remove any left over ice and toss it. leave the ice box open so that mold don't get started in there also.

[sailingdog]

I agree that venting the boat properly will help with the mold problems. I have two Nicro solar-powered ventilators on my boat, and don't have any issues with mold or mildew. Also, make sure that any deck leaks get fixed...

[Everlong]

how do these solar powered ventilators deal with rain?

[sailaway21]

They do just fine. The vent is bubble shaped and the opening for air flow is where the bottom of the vent secures to the deck. Shutting the vent off, to boarding seas, is done from below. The top of the vent is where the solar panel resides. I recommend one of these over a passive vent of similar design. The term "passive" pretty much describes not only the design principle, but the effectiveness as well, the manufacturers claims not withstanding. I was rather disappointed in the lack of longevity, less than two years, of the battery the solar panel charges. I'm ordering a replacement. On full charge it's supposed to run the fan for something like three days and, it's original performance would back that up. You can rig it to run in either an intake or exhaust mode hence "the dog's" system of two vents will set up a nice circulation pattern.

It is highly desirable to get adequate circulation through your boat. Dead air, regardless of the climate you're in, will accelerate mold growth and make the interior of your boat virtually unlivable to those with sensitive breathing equipment. It's a pain in the neck to scrub it down adequately. Keep the air flowing. Keeping an incadescent bulb burning, even in the winter, will aid in raising the ambient temperature and reduce humidity. Good idea.

[sailingdog]

Sailaway-

I have two, and for the exact reason you describe. The one by the companionway is setup as an exhaust vent, and was the first one I installed. This past winter, I installed one just aft of the mast step, and it is an intake fan.

The interior of the boat was 15-20˚ cooler with just the first fan alone, and should be very nice with both. No nasty boat smell, no mold, no mildew.