Do I really need to know how? Yes, if you ever have aspirations of reaching out past your normal casting range. Is it a requirement for most Saltwater Fishing? Yes!
A single haul is a downward pull on the line during only the backcast or only the forward cast. A double haul is a downward pull on both the backcast and the forward cast.
What does the haul do? When you pull swiftly on the line in your line hand, you cause the rod tip to flex which increases line speed.
Note in the illustration note that the hands are close together and they stay pretty much in this position until you haul across the body as you bring the rod forward to compete the forward cast. Casters who make a long and continuous haul cause the rod tip to flex over a greater distance than casters who make a shorter haul. The shorter the haul, the shorter the distance the rod tip will flex and the tighter the loop. A long haul will make wider and less efficient loops.
To make the most efficient double haul, your hand holding the line should follow the reel on the backcast. Keep your hands close together-no more than 12 inches apart. Watch the line end on the water; after the line end has been lifted from the surface, make a haul with your line-hand and the speed-upand-stop motion with your rod hand, beginning and stopping at the same instant. During the forward cast, your line hand travels in front of the reel, staying at the same distance from your rod-hand. Then, the haul and the speed-up-and-stop motion are both again made simultaneously. Make sure that your rod- and line-hands stop together as the cast ends.
To make longer casts, many casters put more force into their rod hand instead of concentrating on increasing the speed of their hauls. Don't increase the length of the haul, just its swiftness.
To shoot line after you have made a quick rod stop in the forward cast, release the line from your line-hand. Make an "0" shape with the forefinger and thumb of your line-hand and allow the line to shoot out through it. To stop the line from shooting too far, close the "0" on the line.