O'Day 240 Mast Raising System
Here's a link to the mast raising system for the O'Day 25. I created a similar system for my 240. It required that I attach a new gooseneck about 3 or 4 in. above the foot of the mast, and on the aft face of the mast. To raise (or lower) the mast, the boom is attached at this new gooseneck. I re-rigged the boom vang with 80 ft. of 3/8 in. double braid. I attached the vang to the clew end of the boom and on to the backstay tang. The topping lift is also attached to the tip of the boom where the vang is attached. For safety, I also attached the main halyard at the same point. A 'bridle' from the clew end of the boom is run to the base of the port and starboard lifeline stanchions that are closest to the chainplates. (I used 1/4 in. double braid for the bridle.) The bridle lines are taunt when the mast is lying horizontally forward, and the boom pointing up, approximately 90 deg. to the mast. Use the purchase of the vang to raise the mast, with the boom acting as a lever. It's important to initially test the system by raising the mast rather than lowering it.