A common problem when raising the M17 mast is that the outboard(upper) turnbuckle will "flop" out from the cabin side to an inverted position. As the mast is raised and your attention is directed elsewhere, the increasing tension on the shrouds will pull the trunbuckle aft and bend it to a nice 45 degree angle. Time to say "Darn", bag sailing for the day, and fork out another hundred for a new turnbuckle.

The solution: Run 1/4" or #12 machine screws with nuts and fender washers laterally through the shackles below the turnbuckle. This permanent fix will hold the trunbuckles upright.