The best way to get a good head start on next years mold crop is to shrink-wrap your boat. Even though the people that provide shrink-wrapping service allow for vents in the cover, there is never enough of them. Take a hydrometer into the cabin in the middle of winter and you will be amazed how much trapped moisture there is in your vessel.
Spend a few pennies more initially and have a custom canvas cover made for your boat. This is not only better for the boat but it keeps a lot of plastic out of the landfills and oh by the way plastic is derived from oil, can you say "dependence on the middle east"? I have used the same cover (with a few repairs) for ten years. I have fastened at least 20 cleats around the cradle to tie the cover down securely; don''t ever tie a cover to jack stands.
Because you cannot remove the stanchions of the C30, you''ll have to build a frame to allow the snow/water from pooling on top of the boat and poking holes in your new cover. Alternatively, you could have the cover designed to have slots in it around the stanchions, Iíve seen this done, it seems to work.
A canvas cover is a little more work the first year but you''ll save money over the long term and your boat will breath easier.