Water Vehicles stability and Metacentre

TRANSVERSE STABILITY
When a vessel is
floating upright
(at equilibrium)
in still water, the
centre of buoyancy
(upthrust) and the
centre of gravity
(downthrust) will
be on the same line,
vertically above
the keel (K).
If the vessel is inclined by an external force
(i.e. without moving internal weight) a wedge of
buoyancy is brought out of the water on one side
and a similar wedge of buoyancy is immersed on
the other side. The centre of buoyancy being the
centre of the underwater section of the vessel has
now moved from point B to B1.




METACENTRE
Vertical lines drawn
from the centre
of buoyancy at
consecutive small
angles of heel will
intersect at a point      
called the metacentre
(M). The metacentre
can be considered
as being similar to a
pivot point when a
vessel is inclined at
small angles of heel.
The height of the metacentre is measured from the reference point (K) and is,
therefore, called KM.