Now that we understand the concept of draft depth (belly) and draft position, lets outline the sail trim controls that are used to adjust those two elements on the mainsail. The controls used to adjust Draft Position for the mainsail are: Boom Vang Cunningham Main Sheet Mast Bend Outhaul INCREASING tension causes the draft position to move FORWARD. DECREASING tension causes the draft position to move AFT. The aft position of approximately 50% produces more power and the forward position of approximately 40% produces less power. The controls used to adjust Draft Depth for the mainsail are: Mast bend Outhaul INCREASING tension reduces the draft depth (belly). DECREASING tension increases the draft depth (belly). Now, unfortunately, the problem is that the settings changes for each point of sail and wind condition. The wind strength is constantly changing and is never constant. Additionally, there are a separate set of controls for the jib and both sails have to mirror each other in order for the boat to achieve 100% efficiency. So what do you do? You could research and outline a zillion books on the subject or you could save yourself a lot of time and effort. Sailboatowners.com sells a Sail Trim Chart that displays every sail trim control and matches them to a particular point of sail and wind condition and gives you the best sail trim control setting. Take a look at it and see if it would be any help to you. In the next session, we'll discuss TWIST and ANGLE OF ATTACK plus the sail trim controls that are used to adjust those two elements.