The squat
effect is the hydrodynamic phenomenon by which a vessel moving quickly
through shallow water creates an area of lowered pressure that causes the ship
to be closer to the seabed than would otherwise be expected. This phenomenon is
caused when water that should normally flow under the
hull encounters resistance due to the close proximity of the hull to the
seabed. This causes the water to move faster, creating a low-pressure area with
lowered water level surface (Bernoulli's principle). This squat effect results
from a combination of (vertical) sinkage and a change of trim that may cause
the vessel to dip towards the stern or towards the bow.
Squat effect
is approximately proportional to the square of the speed of the ship. Thus, by
reducing speed by half, the squat effect is reduced by a factor of four. Squat
effect is usually felt more when the depth/draft ratio is less than four or
when sailing close to a bank. It can lead to unexpected groundings and handling
difficulties.
0 comments:
Post a Comment