LONGITUDINAL STABILITY
Thus far in studying stability, you have been
concerned only with TRANSVERSE STABILITY and
with TRANSVERSE INCLINATIONS. LONGITUDINAL
STABILITY and LONGITUDINAL
INCLINATIONS, or TRIM, should also be
considered.
Trim is measured by the difference between the
forward draft and the after draft. When the after draft is
greater than the forward draft, the ship is said to be
TRIMMED BY THE STERN. When the forward draft
is greater than the after draft, the ship is said to be
TRIMMED BY THE BOW or TRIMMED BY THE
HEAD. As a ship trims, it inclines about an athwartship
axis that passes through a point known as the CENTER
OF FLOTATION (CF).
The mean draft that is used to enter the draft scale
to read a displacement curve is the draft amidships.