You are way ahead of me in sailing the Cal21. I got the boat last fall on a trailer. The prior owner bought it a couple of years ago and left it on the hard in his backyard through 2010. He had very little info for me. I expect to test sail her this coming Monday. Had to do repair work on rudder as well as figure out the rigging. The interior is still a mess, but not a major concern of mine. I have spent a lot of energy trying to learn about the keel and keel attachment. This boat has a permanent connection which I am lead to believe is detrimental to sailing. I would like to set it back to original design. Regarding back stay, I have read that putting a dual wire with an adjustment back there is good. But in general on rig tension I have little to offer at this point. My boat has two jibs and the roller jib has hanks on it which is also a puzzlement. There is a roller on the jib halyard and I found a small Harken furler in a parts box. Not sure prior owner was a sailor or knew what a roller furler was. Of course that may be the way he got the boat.