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.
Torque Calculation Formula for Speed below 25 Knots C = S x [ (0,4 Lg) Lc ] x V² x K
Start the calculation
C = 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
8 metres
VHM 40 DTP code 2200075
VHM 32 DTP code 2200059
10 metres
VHM 40-254 code 2200496
12 metres
14 metres
VHM 50 DTP code 2200497
This chart is given as an indication only
Description | Working principle | Assembling diagrams | Selection of a system