| For boats fitted with a rudder, the torque of the rudder or rudders is calculated as per the 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 (balance). |
C = S x [ (0.4 Lg) – Lc ] x V² x K C= Torque in kgm S= Total surface of rudder (H x Lg) in sq. mH= Height of rudder in mLg= Width of rudder in mLc= Compensation width in mV= Maximum speed of the boat in knots K= Coefficient in function of total rudder angle Port to starboard 70°K = 15.89Port to starboard 80°K = 17.80Port to starboard 90°K = 19.52 Corrections in function of the type of boat: For a boat with a steering nozzle C x 2.0For twin engine power boats with 1 rudderC x 0.5For boats fitted with several rudders (catamarans, monohulls)Multiply the calculated torque result by the number of rudders fitted on the boat. |
Torque calculation
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