Most often a swage stud (on the wire) is right hand threaded so when all is set up well the turnbuckle will tighten when the body is turned counter-clockwise. Note in my earlier post (I really should register one of these days - every post you've seen recently with the same unregistered name is the same guy - me) that I mentioned the turnbuckle having a toggle at each end. More likely (especially if this is an older boat), you probably have a fork at each end. If so, you should consider adding a merriman style toggle or replacing one of the forks with a toggle at the bottom end of the turnbuckle when you re-rig.