On a unirig cat, like the H14, the main sail and the rudders need to work in (perfect) harmony. As you sheet in the main, the boat will tend to round up into the wind. Since there is no jib to oppose that tendancy, you have to control it with the rudders. This is where the harmony part comes in. If you honk in the sheet real fast, the boat rounds up to irons. If you yank hard on the tiller, the rudders brake and slow the boat and then the boat can weathervane to irons! So after your tack, sheet in smoothly and quickly but not too quickly and not all the way to block-to-block. Control the head up tendancy with a little bit of rudder. After you are on course and have built up some speed, fine tune with the sheet.