|
Day Skipper - Part 1 - Displacement,
Planing and Semi-displacement craft
Displacement craft
Generally, round bottomed with a maximum displacement hull speed that
is determined by waterline length. The longer the waterline, the faster
the hull goes in its displacement mode. At its displacement speed, the
whole hull remains in the water.
Planing craft
Planing hulls have become very popular recently. The underwater hull section
has changed from a round bilge to a deep-vee section, which gives a softer
ride at speed, and by increasing the engine power sufficiently
the boat can be propelled at fast enough to plane over the surface
of the water rather than push its way through it.
Semi-displacement craft
By increasing the engine power, certain displacement craft can be pushed
through the water at more than their displacement hull speed. When this
happens, the bow rises out of the water as speed increases and they are
said to be in a semi-displacement mode. There are two main types: the
narrow-beam, round-bilge Nelson-style (left) and hard-chine examples like
this Grand Banks.
|
