Backing a boat trailer down a ramp isn’t all that hard, but like establishing proper lead in wingshooting, it takes practice.
The key fact to bear in mind is that the trailer will always go in the opposite direction of the tow vehicle. This causes a great deal of confusion and is one of the main reasons you see guys jockeying up and down the ramp with a trailer that seems to have a mind of its own. Here’s an easy way to master the maneuver:
 Find an empty parking lot where you can learn to gain control over your trailer without worrying about a long line of irate fishermen behind you. After you shift into reverse, place your left hand on the bottom of the steering wheel. When you move your hand to the right (which turns the steering wheel and the front tires to the left), the trailer will move to the right (a). When you move your hand to the left (which turns the steering wheel and front tires to the right), the trailer will move to the left (b). It takes a little getting used to (and your brain will fight you at first), but it works.
 Move slowly. Most beginners back up too fast. If the trailer starts to move in the wrong direction, stop. Pull up, straighten the trailer, and start again. Trying to correct a wayward trailer will only make matters worse. Once you master the parking lot, you’re ready for the ramp.