Tuning and speed tips
While it may be tempting to rig a bigger sail in an effort to go faster, the opposite is most often the case. You will find that a smaller sail gives you more control and will actually increase your speed. This is due to the fact that a smaller sail can be sheeted tighter, reducing the aerodynamic drag. If you are fighting for control and cannot keep the sail fully sheeted in, any portion of the sail that is flopping is also causing drag.
When rigging your sail, rig it so that it is as low on the mast as possible, while still allowing room for the boom to swing over you. Many sails have an adjustable head, which is a line or webbing from the head of the sail to a mast cap. Lowering the sail also keeps you from hiking or flipping.
Reefing a sail by rolling the bottom portion around the boom lowers the center of effort and also reduces the area of the sail. To reef a sail, slide the sail off the mast. Remove the boom, and unthread the sheet from the blocks. Firmly tie the foot of the sail to the front of the boom. Roll the sail tightly around the boom, taking care to keep the mast sleeve from binding with the block just behind the boom jaw. Continue rolling until the aft end of the boom is just below the outhaul, or clew of the sail. The front of the boom should be in the area of the cutout used for a regular windsurfing boom. Tie the aft end of the boom to the clew. Slide the mast into the upper part of the sleeve, fitting the boom jaw over the mast. The sail will want to unwind off of the boom, don't panic. Rethread the sheet, and rig the mast on the sailer. At this point the boom will probably be high on the mast, since the foot of the sail has been raised. If the sail has an adjustable head lower the boom so that the sailer is not as likely to tip over. Use a bungee cord to secure the boom to the mast so that the sail does not unwind.
We often use sails that have had the bottom area removed, so that they look more like a traditional sail. They work great, with less hiking and more control.
Next: Sailing Safely at Higher Speeds