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:
Torque Calculation Formula for Speed below 25 Knots
C = S x [ (0.4 Lg) – Lc ] x V² x K
Once the torque is known, the appropriate cylinder is selected and one or two manual pumps will be added.
Note: If the selected pump has a higher flow rate in order to reduce the number of turns lock to lock, it will be necessary to use a steering wheel with the maximum recommended diameter.
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||VHM 32 DTP|
|10 metres||VHM 40-254||VHM 40 DTP|
|12 metres||VHM 40-254||VHM 40 DTP|
|14 metres||VHM 50 DTP||VHM 40-254|