Oh, wait a minute, now I get what you had in mind, Mark.
I didn’t notice this morning that the red line in your drawing is labelled “zipper”.
You’re planning to have a zipper on each side, with the top section of the cover above that red line completely zipping off. Is that right?
So, the top piece comes off when departing, gets folded up, and stowed away. On return, the crade lines guide the sail into the bottom piece, and the top part gets laid out and zipped back on from both sides. Now, am I understanding you?
If so, sounds like a really interesting idea that should work pretty well.
If you pull the slack in your reefing lines back to the sail clew, you won’t need any slots for them.
Depending on how long the zippers need to be, I don’t know whether you might have trouble sourcing a continuous zipper of that length.
And the top piece might need a section that loops around the mast, so that it doesn’t flip back in a breeze and leave the head of the sail uncovered.
Neat!
– Bob
Me Gusta
Nonsuch e26U #233