Re: Back stay boom supporter broke - now what?
You could get something like a shroud cleat, put it high enough on the back stay to hold the boom up out of the way and attach a bungy to it. Once the main is raised you can detach the bungy and re-attach it to a point on the stern rail if you have one. I've sailed some J-24's that did it this way. I think they cut one hook off the bungy and tied that end to the cleat and kept the hook end for the boom.
Barton Marine Shroud Cleat with Shackle Eye | Bosun Bobs.com