Install the trailer guide on's on the trailer at the point where the boat beam is the widest or at the fender wells preferably at the widest point of the beam. This gives you the 3 points needed to position your boat on the trailer in the same position each time you load it. The guide on's will keep the boat from moving from side to side and the winch connection point will align the boat as you winch it into the proper loaded position, it will form an imaginary V for the boat to fit in. I have them on my trailer and I think they are mounted in front of the fender wells. Mount them to allow a little wiggle room. My guide on's have PVC pipe over the uprights. Make sure the top edge of the guides are above the gunwale(sp) and contacts the rub rails or you will mark the finish on your boat where the top edge drags on the side. Don't ask me how I know!