The position of the sails and the strength of the wind control your sailboat's speed. You can, however, do two things to adjust the velocity. Follow these steps.
To speed up, position your sails to catch as much wind as possible. Tighten your sails, but do not over tighten or you will “spill” wind.
Step2
Deliberately spill wind to slow the boat. Tighten the sails as much as you can. You can also slow down or stop by lowering your sails completely.
Step3
Drop anchor to keep from drifting.
Tips & Warnings
Remember that the other factors you can’t control, such as wind speed and direction, will affect your boat's velocity.
Do not let the sails get loose enough to flap heavily in the wind, or they could tear or suffer other damage. If you want to slow down or stop, you can take down your sails instead of just loosening them.