Just a bit more input on he subject, from Jay Kirby at Dwyer Mast: "We normally do not use exit plates for small boats; rather we use slots. The size is 7/16" by 2-1/2 or 3". Theyexit at around 4 or 6 feet from the base of the mast depending on where the cleats or turning blocks are located.They are staggered fore and aft of the centerline and above and below each other on opposite sides of the mast.They do weaken the mast; we would not hesitate to use then on a new mast but don't know how a mast as old as yours would fare." Well, I'm going to do it anyway. Some of us don't think things from 1975 are really that old... Nick C.