Abstract
There are many characteristics attached to a ship, such as stability characteristic, watertight characteristic, steer characteristic. etc. Among the above-mentioned ship’s characteristics, the stability characteristic is the most important characteristic. To maintain proper ship’s stability characteristic is a very important task of the ship’s officers and crew on board. While at sea, there are many thing that affect to ship’s stability. The effects of free surface of liquid in partly-filled tanks on ship’s stability and calculation of the effects of free surface based on ship’s stability booklet will be given in this article.