“Just keep her sailing on this downwind course,” Jerry said. “Head for that lighthouse the way you were before, and keep an occasional eye on the hawk. As long as the wind isn’t dead astern, we shouldn’t have any more jibing troubles. As soon as we get out into open water, we’ll find an easier point of sail. We can’t do that until we’re clear of the channel, though. When we are, we’ll reach for a while, and then I’ll show you how to beat.”
“What’s reaching?” Sandy asked. “And what’s beating? And how do you know when we’re out of the channel into open water? And how do you even know for sure that we’re in the channel now? And how....”
“Whoa! Wait a minute! Let’s take one question at a time. A reach is when you’re sailing with the wind coming more from the side than from in front or from behind the boat. Beating is when the wind is more in front than on the side, and you have to sail into it. Beating is more like work than fun, but a reach is the fastest and easiest kind of a course to sail. That’s why I want to reach as soon as we’re out in open water where we can pick our direction without having to worry about channel markers.”
“How come reaching is the fastest kind of course to sail?” Sandy asked. “I would have guessed that sailing downwind with the wind pushing the boat ahead of it would be the fastest.”
“It sure seems as if it ought to work that way,” Jerry said with a grin. “But you’ll find that sailboat logic isn’t always so simple or easy. When you’re running free in front of the wind, you can only go as fast as the wind is blowing. When you’re reaching, you can actually sail a lot faster than the wind.”
“I’m afraid that I don’t understand that,” Sandy said. “How does it work?”
Jerry paused and thought for a minute. “You remember what Quiz said about the sailboat working like an airplane? Well, he made it sound pretty tough to understand, what with all his formulas and proportions, but actually he was right. A sail is a lot like an airplane wing, except that it’s standing up on end instead of sticking out to one side. Well, you know that the propellers on a plane make wind, and that the plane flies straight into that wind. You see, the wind that comes across the wing makes a vacuum on top of the wing surface, and the plane is drawn up into the vacuum. You get a lot more lift that way than if the propellers were under the wing and blowing straight up on the bottom of it.”
“I see that,” Sandy said. “And a propeller blowing under a wing would be pretty much the same as a wind blowing at the back of a sail. Right?”
“Right!” Jerry said, looking pleased with his teaching ability. “Now you have the idea. When you have a sail, like a wing standing up, the air that passes over the sail makes a vacuum in front and pulls the boat forward into it. Actually, the vacuum pulls us forward and to one side, the same as the wind from the propeller makes the plane go forward and up. We use the rudder and the keel to keep us going more straight than sideways.”
Sandy shook his head as if to clear away cobwebs. “I think that I understand now, but it’s still a little hazy in my mind. Maybe I’ll do better if you don’t tell me about the theory, and I just see the way it works.”