Observers

You must have an observer when skiing. The law says that the boat driver must be at least 15 years old, or be sitting beside and under the direct supervision of a person 15 years old, and the observer must be at least 7 years old. Now, you could argue that a 7 year old is not necessarily mature enough to maintain a constant watch on the skier, and a driver in this situation would need to maintain a watch also in their rear view mirror, for example. But ideally, the boat driver should concentrate on driving and the observer on observing.
Safety tip #1 The observer must maintain constant vigilance on the skier and immediately transmit any hand signals from the skier to the driver.
Safety tip #2 When the skier is ready to start and yells Hit it! the observer should repeat this to the driver. When the skier falls off the observer should yell He shes off! to the driver.