Comparing horsepower with kilowatts

The simple answer, though slightly inaccurate, is that an electric motor with a power output of 'X' kW is comparable in terms of performance to a conventional diesel engine with two to three times higher horsepower.

We often get asked, “How does the horsepower of a diesel- or gas engine compare to the kW rating of an electric motor?”

The simple answer, though slightly inaccurate, is that an electric motor with a power output of 'X' kW is comparable in terms of performance to a conventional diesel engine with two to three times higher horsepower.

Now, horsepower is not a unit that you would normally see with electric motors. The power of an electric motor is expressed in kilowatts (kW). But we understand the question as often people want to understand which electrical motors would be suitable for replacing the combustion engine in their boat, and then determine their power requirements.

The horsepower (hp) is a unit dating from the time that the performance of steam engines had to be compared to horses. Most countries now use the SI unit Watt (W) for measurement of power. With the implementation of an EU Directive in 2010, the use of horsepower in the EU is today permitted only as a supplementary unit.

A simple way to convert kW to hp (metric) is to multiply the power value in kW by 1,359. A 10 kW electric motor therefore delivers an equivalent of 13.59 hp.