Diesel power and horsepower per tonne
Horsepower is not a speed prediction.
Conventional formula
hp/t = (engine_power_kW / 0.745699872) / (displacement_kg / 1000)In plain language
Power is the rate of doing work. Rated output is declared at an engine speed and under a convention. We store kW canonically; mechanical horsepower and metric horsepower are not exactly the same unit.
How to interpret it
Horsepower per tonne divides mechanical horsepower by displacement in metric tonnes. Here 1 hp = 0.745699872 kW. The formula version makes that choice explicit.
Why it matters
Normalising by weight makes an initial comparison more informative than power alone.
Limitations
Propeller, reduction ratio, power curve, loading and conditions remain essential. We do not infer consumption or speed from this ratio.
In practice
An original engine belongs in the catalogue; a repower should be recorded on the individual boat.
Sources & reading
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