For boats fitted
with outboard motors
To select a steering system in our
range, first determine the maximum horse power developed
by the outboard motor(s) and the rotational direction of
the propellers on installations with several motors.
For boats fitted with a rudder
with speed not exceeding 25 knots, the torque of the
rudder or rudders is calculated according to following
formula and corrections.
It must be known that the torque necessary to manoeuvre
a boat depends on :
- the speed of the water flowing on the surface of the
rudder at a certain angle,
- the rudder size,
- the total sweep of the rudder (and part of the boat),
if the rudder shaft is not perpendicular,
- the compensating surface of the rudder.
Calculation Formula for Speed below 25 Knots
C = S x [ (0,4 Lg) Lc ] x V² x K
= Torque in kpm
S = Total surface of rudder (H x Lg) in sq. m
H = Height of rudder in m
Lg = Width of rudder in m
Lc = Compensation width in m
V = Maximum speed of the boat in knots
K = Coefficient according to total angle of rudder
Once the torque is known, the
appropriate cylinder is selected and one or two manual
pumps will be added accordingly.
Warning : If you select a pump
with a higher flow rate in order to reduce the number of
wheel turns, you will have to fit a wheel au diamètre conseillé.
For pleasure boats with planing or semi-planing hulls
and speed exceeding 25 knots, the cylinder may be
selected by using the chart below.
Length of Hull
Cylinder Type 1 Rudder
Cylinder Type 2 Rudders
VHM 40 DTP code 2200075
VHM 32 DTP code 2200059
VHM 40-254 code 2200496
VHM 50 DTP code 2200497
This chart is given as an
Working principle |
Assembling diagrams |
Selection of a system