The length of your head stay will depend on the year and whether Bob or Jerry built the boat. Bob's M 15's, some, but perhaps call (he can tell you) ,have a slightly longer head stay than an '86 built by Jerry. The reason is that Bob's stays and shrouds attach to a hound rather than the single bolt passing through the mast. This information will be very helpful if you are ordering a new jib. For those who have the single bolt, I highly recommend using a nylock or doubling the nut on the bolt. I have sailed many years without a problem. But at Lake Havasau somehow the single nut I had up there came off and I almost lost my rig. Fortunately, I had installed a strong shackle to the forward holes on each chain plate. When the starboard shroud hit the water, I dropped the sails and lead a halyard to either side and secured them to the shackles and used the topping lift as a fore stay. I motored back to port with none the worst for wear except for the excess adrenaline that was still my system. Happy sailing, Bert Felton