If you have a boat and do not do anything to maintain the moisture level on that boat, especially when storing it, you may ruin the risk of mold and mildew growing on upholstered surfaces and corroding all of the electronic components needed to run the boat. Boat dehumidifiers will help control the moisture introduced by the environment.
Boat dehumidifiers can be used either during or after storage to remove moisture inside the boat cabin. Other moisture control products or devices can help remove moisture as well. Silica based products come in all shapes and sizes of boxes or bags that can be strategically placed or hung throughout the cabin to absorb moisture.
Anything that will draw the moisture out of the air will help deter mold and mildew from forming over the winter season when the boat is not being used. Keeping moisture from getting into sensitive electronic compartments will keep your boat from needing costly repairs and replacement of expensive components.
Mildew and mold thrive in moist and humid environments. If you do not control the amount of moisture in the air inside the cabin during storage then you may end up with mold and mildew growing on every surface in the cabin and even embedded in the upholstery.
Hard surfaces can be cleaned effectively with a bleach water solution but the upholstery may never be the same. It will probably need to be replaced if this happens. It may be a good idea to clean every surface thoroughly with a bleach water solution before closing the boat up and sending it to storage along with the moisture control items or dehumidifiers.
This could just maybe save your bacon when it comes time to open the boat back up for the season. Hopefully there will be no musty, mildewy smell inside the cabin at all when boating season comes around again.
A possible cheaper method for moisture control is using cat pan litter. You could get double the benefit with the cat litter, moisture control and odor control. I have never tried this but seems to me those are the things that cat litter is made for so it would be worth a shot to find out.
Experiment before you try it for a full storage season and if it works then go for it. Cat litter is probably a lot less expensive than those other products. Pick one with a nice fresh scent or find an organic blend that has no perfumy smell.
Once you take the boat out of storage and get her back in the water you should open her up and let her air out some with a slow ride around the bay to get all the stagnant air replaced with fresh. A marine fan is another great idea to use when the boat is docked at the marina.
Boat dehumidifiers are the best way to decrease that amount of moisture inside the cabin or inside storage areas of the boat. Never put life jackets or other equipment away when it is wet. Always let it thoroughly air dry before stowing it away.