Topic:

-How and why a sailboat goes.  Turning the boat by coming about.

Objective:

-Students will learn how a sailboat moves and how to turn the sailboat.
 

Skill:

-Understranding how the boat moves.  Turning the boat
 

Equipment:

-Mainsail model
 

Lesson Activity:

 I. Introduce how the sailboat accually moves.

   A. . As wind approaches the leading edge of the sail, it separates and flows along both sides of the sail from luff to
leech. The air on the windward side reaches the leech first, since it has a shorter route to travel. The results is lower pressure on the leeward side of
the sail creating a lift perpendicular to the wind.

Another way to look at how an airfoil works is the wind on the outside curve is spread out, so its pressure is
lower. The wind on the inside piles up, and its pressure is higher. The result is that the high pressure inside
pushes on the sail, while the low pressure outside creates suction. Together they make a push-pull effect that
drives the boat forward.

The push-pull action drives the boat forward and sideways. The centerboard or keel prevents the boat from
slipping sideways..

    B.  Notebook example

     1.  Taking a piece of notebook paper and holding it up horizontally by the two corners in front of your face. The far edge of the paper will drop down because of gravity. Now blow hard along the top surface. The paper will be sucked back up to the horizontal. Your sail works in the same way.
 

    C. Understanding how to come about.

     1. Every boat undersail is on either a starboard tack or port tack. There are two ways to change directions. If going upwind the term used is coming about, this is accomplished by putting your bow through the no-sail zone. If going downwind the term used is jibbing, this is achieved by passing the stern through the no-sail zone.

     2.  Use the mainsail the instructor made for the students and move through these steps.

       1. Ready About is given by the helmsman to alert the crew.
       2. Helms Alee is given at the moment he pushes the tiller (this is the same the rudder) toward the boom.
       3. By moving the tiller the bow moves across the no-sail zone and will soon fill with wind.

     3.  Go through all steps with each student.  Be sure the instructor has gone through this process in order to be sure it works for the   class.
 
 

Review:

-Gather students around the instructor ask them the basic calls when coming about.
 

Assessment:

-Do the students understand how the sailboat accually moves?

Have the students do the notebook paper activity.
 
 

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