For several reasons. First, every boat but the current boat has used the mast as a ridgepole for the winter cover. Second, I do believe that the rig is stressed when the winter storms blow in off of Lake Erie. Third, every sailboat I have ever seen that was blown over in winter storage had the mast up (including a few at our own club and the marinas on either side).

We pulled the mast this past Saturday. I really don't know how long it has been up. I will be using the opportuinity to service the wind instruments, the nav lights and replace the VHF antenna.