The admiral has been at it again -- check this out:

5 bags in one! A simple velcro tab arrangement around the top edge of the bag makes it easy on and easy off!

I still have to install some small grommets in the bottom for water drainage.

There is also a split (the velcro point) in the bags at the aft base of the mast for the turning block attachment point.

 

The pattern was a simple flat piece with the 5 bags pleated onto it. A long velcro tab hangs out the end. Kind of like this: