Engine Power Requirement Calculator
Estimate the engine power required for your vessel based on displacement, target speed and hull type.
Use the result as a first guide when specifying a propulsion system.
Units
Vessel details
Full load displacement including fuel, water, stores and crew.
kg
The cruising speed you want to achieve at full load.
knots
Length of the hull at the waterline, used to calculate theoretical hull speed.
m
Why this power range?
The calculated minimum is a first-pass estimate based on vessel displacement, target speed and hull type.
The recommended range includes reserve for real-world conditions such as loading, hull condition,
propeller choice, wind, waves and installation losses. Final engine selection should always be verified
against the complete propulsion system.
Calculation method
Power (HP) = (Displacement in tonnes ^ 2/3 × Speed³) / Hull Factor
Hull factors used:
Displacement hull = 45
Semi-displacement hull = 70
Planing hull = 100
Recommended range:
Calculated minimum × 1.15 to calculated minimum × 1.40
Hull speed:
Hull speed (knots) = 1.34 × √waterline length in feet
This is an estimate.
For a final engine selection, verify the result with your VETUS dealer or a qualified marine engineer.
Propeller selection, gear ratio and installation losses will affect the final power requirement.