VetusOnline Thruster Calculator (wind-based)
Calculates required thrust (kgf) from wind load and lists suitable VETUS thrusters. Weight and draft add a guidance margin; catamarans include an additional hull-form allowance.
Inputs
Vessel type
Catamarans use the total vessel wind area and add a 10% hull-form guidance allowance.
Thruster position
For stern thrusters we use waterline length as lever arm (B).
System type / voltage
Filter electric thrusters by voltage, or select Hydraulic.
Boat length (m)
Overall boat length (used for A = 0.5 × boat length).
Waterline length (m)
Used as lever arm B for stern thrusters: F = T / B.
Distance from aft (transom) → tunnel center (m)
Used as lever arm B for bow thrusters: F = T / B.
Wind area above waterline (m²)
Total projected side area affected by wind. For a catamaran, enter the complete vessel side area — do not double it just because there are two hulls.
Boat weight fully loaded (kg)
Guidance factor only (does not reduce the wind requirement).
Draft / Dybgang (m)
Guidance factor (deep keel / more sideways resistance).
Wind input
Switch between m/s and Beaufort. Calculation uses m/s internally.
Wind speed (m/s)
Example: 8.0 m/s ≈ Beaufort 5.
Reduction factor (streamlining)
Typical rule-of-thumb: 0.75.
Thruster group filter
Optional: narrow down the displayed groups.
What the tool does
Wind pressure: p = 0.613 × V² (N/m²)
Wind force: Fw = p × Area × reduction
Turning moment: T = Fw × A (A = 0.5 × boat length)
Required thrust (wind): F = T / B
Guidance margin: weight + draft apply a capped multiplier (does not reduce the wind requirement).
Catamaran allowance: ×1.10 is added after the weight/draft factor to allow for the different hydrodynamic behaviour of two hulls.
Two-thruster catamaran: the total system requirement is divided equally between two identical thrusters.
Wind area is the total projected side area of the complete vessel. Bow: B = distance from aft (transom) → bow tunnel center. Stern: B = waterline length.
Important (vejledende): This calculation is guidance only. If the tool cannot calculate a clear result, or if you are in doubt about the inputs or the recommendation, please contact support.