Boats are moist even on the sunniest of days. They make a great incubator for all kinds of green and yellow, and blue growths. This is not just a problem in the summer but over a winter with fluctuating temperatures it is a constant battle. Here are some ways to manage the mold.  

In the fall when you winterize your boat remove anything that is made from any kind of fabric or porous material. Yes, it is a bit tedious to lug everything off your boat just to lug it all back in the spring, but it is the right thing to do. Store it in a dry location that will not have a lot of fluctuations in temperature.   If you can prevent condensation that you can generally control mold.

I have read about this next tip and will try it myself this winter. In your boat after you have removed everything that might host bacteria, place a few containers of chlorine. The gas that this puts off will discourage the multiplication of bacteria.

Have Clorox spray handy all the time and wipe down walls and ceiling where you see anything growing.