Page 3 talked about how boats with a v-hull do a better
job at providing a smooth ride than boats with a flat
hull. However that comes at a cost. Boats with
v-hulls use much more gas than boats with flat hulls.
The reason for this is because of the friction between the
surface of the boat hull and the water.
Friction against a boat hull is by far the biggest thing
affecting the fuel efficiency of a boat. Boats with
v-hulls have more surface area in contact with the water than
boats with flat bottom hulls. As a result, there is more
surface for the water to grab on to which means a boat motor
has to exert more power to push a v-bottom boat as opposed to
a flat bottom boat. More power means more gas which
means more expense ("Friction", Britannica).
To counter this, many boat builders design boats with
"Spray rails" that help reduce the wet surface area of a
boat (see below). Another way that has become
popular is by putting underwater "wings" on a boat
hull. When the boat gets up to speed, these wings
generate a force upward which actually lifts most of the
boat out of the water and greatly reduces the surface area
in contact with the water. The photo at the
beginning of this page is a boat with water wings while
underway.
