Trim and Longitudinal Stability
Stability of a ship is defined as its ability to return to the normal operating attitude when disturbed from it by transitory forces or moments. This concept will be explored in more detail in the next chapter, but here it is worthwhile to note that most ships have sufficient longitudinal stability in their intact condition and, therefore, it can be considered to be of little interest to us in terms of safety. However, the longitudinal stability affects the trim of the vessel directly, and trim is a very important factor in determining the operational efficiency of ships. We shall, therefore, briefly examine here the longitudinal stability with emphasis on trim.