I made a similar post on the Hobie forum but just in case there's a knowledgeable 21SC owner here I wanted to cover my bases. I recently acquired a 1997 Sport Cruiser, Serial #945. Amazingly the former owner had the gennaker but not the other important bits like boom, main sail and jib. It looks like there are a couple companies that can make the sails and the boom can be purchased new through Hobie. I was able to confirm that the 21SC boom uses the same aluminum extrusion as H16 boom.
Are there any 21SC owners out there that could verify the length of the 21SC boom stock? I'd like to find out if I could modify an H16 boom as they are cheap to pick up used and I have the reefing handle assembly.
Also, I've found that Whirlwind and SLO both offer replacement 5 or 6oz Dacron sails. Are there suggestions for any other sail makers that could produce an inexpensive main and jib that I should consider? Or any productive comments about SLO or Whirlwind? Thanks.