Water skiing usually begins with a deep water start, with the skier crouching down in the water. When the skier is ready, the driver accelerates the boat to pull the skier out of the water.
In addition to the driver and the skier, a third person known as the spotter/observer should be present. The spotter’s job is to watch the skier and inform the driver if the skier falls. Communication between the skier and the occupants of the boat is done with hand signals.
Speeds vary from as slow as 22 kilometres per hour (14 mph; 12 kn) up to 58 kilometres per hour (36 mph; 31 kn) for slalom water skiing; up to approximately 72 kilometres per hour (45 mph; 39 kn) for barefoot skiing, and approaching 190 kilometres per hour (120 mph; 100 kn) in water ski racinG. The length of the rope will also vary widely dependent on sport discipline and skill level.
Reference: Wikipedia Water Skiing