Best backing job I have ever seen was at a lake in Georgia. There was a fishing tournament going on and I just happened to be there fishing (not in tournament). The ramps actually had concrete curbs on both sides so the "lanes" were very clear. They were at least 40 yards long. As I was slowly and carefully backing my boat down the ramp, one of the pros was doing the same on the ramp next to me. He had his partner in the boat and he must have been backing about 40 mph. When the trailer tires hit the water he hit the brakes. The boat launched perfectly into the water and the guy in the boat had the engine down and running in seconds. The truck driver was parked and in the boat with his partner before I got my boat in the water.