Answer:
force
Step-by-step explanation:
Gravity and buoyancy are the two key forces that operate on a stationary sailboat. The power of the wind pulls on the sail in order for the boat to move which allows the boat to move. The powers are now unbalanced, which is apparent from the acceleration of the ships.
The boat accelerates until the forward portion of the force from the sails is matched by the drag from the water.