No set length
There's no rule that halyards have to be one prescribed length. Take the height of your mast, double it and then add whatever it takes to make it work for you. If your halyards are led aft, you'll have to add more. If not, they can be shorter but do you think you might want to lead them aft? Err on the side of safety and cut 'em long. You can always trim them to suit your needs later.BTW, according to the specs on this site, the C22 mast is 29'1".LaDonna