Hobie and others sell several systems for self-raising masts. The one you describe sounds like a gin pole attached to the mast. Works great. Another commercial system is to have a pulley on the mast support of the trailer and run a line (connected to a winch at the bottom to middle of the trailor mast support) up through that to the mast. The pulley must be at least 30" above the mast height.



Good luck.



John