[the problem with not using the jib is that the boat is so much slower you can hardly get it to turn at all] sounds like too much rudder. forcing the rudders drastically slows the boat. the idea is to use the main sail to head up by sheeting in while gently guiding the boat into a smooth arc through the tack. the boat should not stop during the tack. it may take some practice. this is basically the same technique used in racing, if you are going so slow in the middle of the tack that the jib is needed to blow the bows down onto the new tack, the rudders have probably been used too aggressively during the beginning of the tack.