Check the assembly manual on this site.
https://media.hobie.com/digital_assets/H18&SX_Manual.pdf?_gl=1*1bd1jxj*_ga*MTAwNzAwMzEzNi4xNjg2MTgwNjE2*_ga_Z9H2YY9GHV*MTY4ODcyNTE0OS41MC4xLjE2ODg3MjUyNzkuMTkuMC4wThe aft end of the boom will not be supported until you raise the mainsail and pin the outhaul car to the clew fitting on the sail. If this bothers you, then you can use the main halyard to hold the boom up before you raise the mainsail. Just pin the ring of the main halyard to the outhaul car, pull the halyard so the boom raises about two feet off the tramp, and tie off the halyard.
Its also very important when you do hoist the mainsail, that you understand how the halyard ring/hook system works and how to engage the ring into the hook. If you don’t lock in the halyard hook, then your mainsail will slip down the mast and your boom will end up being very low to the trampoline.
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