Patrick Mark, age 10, of Mississauga, Ont., Canada, for his question:

HOW DOES A SAILBOAT MOVE AGAINST THE WIND?

Early in the 1900s steamships came along to replace commercial tall masted sailing ships. But the sailors' love of billowing canvas sails and the great challenge provided by sailing along in a strong wind continued. Today sailing is a favorite sport with millions of people around the world. The thrill of sailing in a fresh breeze, followers of the sport believe, can't be duplicated with any other activity.

For a boat to sail in other directions than just the way in which the wind is blowing, a boat must be designed and rigged to use the force of the wind.

Without control, a boat would only travel downwind. But add a rudder and you've taken the first step to direct your course. Next add either a keel, centerboard, bilgeboard or leeboard. The rudder will be used for steering and the centerboard will prevent sideward movement.

There are three basic maneuvers in sailing. First is sailing into the wind. You can't go directly into the wind, as you can imagine, since the sail would only flap wildly. What you most do is tack, or follow a zig zag course. Your boat can head tto within 45 degrees of the direction from which the wind is b .owing before you lose a driving force. The keel will keep ~rou from moving sideways, although great skill is required. After a certain distance upwind, a sailor must know when to tack again and set his next zig zag course.

Second of the basic maneuvers is sailing across the wind. With this method you'll move faster than sailing in any other direction. This sailing maneuver is also called reaching or sailing with the wind abeam.

Third type of sailing is going with the wind. This is also called sailing before the wind or running. Strangely, running is not so fast as sailing across the wind. While the sail is taking the full blast of the wind, it is also making its own resistance at the same time.

Trimming and tacking are two of the skills a sailor must learn. Trimming means adjusting the sails to obtain the full advantage of the wind. When a boat is running before the wind, the mainsail must be at right angles to the boat's direction. when moving across the wind, the mainsail extends about halfway out from the boat at a 45 degree angle; and when moving into the wind, the sail should be trimmed as parallel as possible to the boat's direction.

Small boats can easily capsize if they are not handled properly. Sailors have to learn how to place their weight and how to relieve dangerous pressures of the wind in the sails so the boat does not tip too far. This is done by slacking off, or letting the sails out, so some of the wind can spill out.

All sailors in small boats should wear life jackets at all times.