We had sailed the boat from Rhode Island to Annapolis pre-boat show and left it at a CW contributor's dock.
Mid winter, we drove down to check it out -- very damp below and full of mildew (there had been snow on deck etc.). We spent most of the weekend cleaning up the mildew and installing a solar vent. When my friend next drove down to see the boat, it was bone dry inside. Well worth the investment.