The boat has an
overall length of 36 ft and the lateral wind draft measures 190 sq.ft.
It is required that the bow can still be controlled easily when a wind
force of 20 knots applies. At a wind force of 20 knots, the wind
pressure is:
p = 1.0 to 1.9 lbf/sq.ft i.e.p. (average) 1.45 lbf/sq.ft.
The required torque reads:
T = windpressure x wind draft x reduction factor x
distance center of effort to pivot point, (=appr. half the ship's
length)
T = 1.45 lbf/sq.ft x 190 sq/ft x 0,75 x 36 ft/2 =
3719 ft.lbs.
The required Thrust Force is calculated as
follows:
F = Torque/distance between the center of bow
thruster and the pivot of the boat
= 3719 ft/lb / 34.5 ft = 107.8 lb
The VETUS bow thruster which is most suitable for
this particular vessel is the 121 lbf model.
Always bear in mind that the effective
performance of a bow thruster will vary with each particular boat, as
the displacement, the shape of the underwater section and the
positioning of the bow thruster will always be variable factor. |