Many flaws in the tests:
- The boats are clearly moving the direction of the electric boat meaning the diesel has to overcome both the electric motors and momentum.
- Cavitation may be hampering the diesel since it is moving backward it isn't getting a clean bite on the water
where the electric boat is moving into clean water presumably getting a better bite.
- There was no indication what propellers were used on each boat.
- There was no indication of what gear
ratio was used on each boat.
- With the Diesel moving backward was it able to get the prop up to speed and take advantage of the larger HP (vs the electric which was moving forward making it easier to get the prop up to speed).
Of course, it's a pointless test:
- If this was a key performance aspect of cruising boats, it would be easy to add a reduction gear
to the diesel so it would have even more torque than the electric motor
and could turn an even larger prop. The fact is off the line thrust isn't a key cruising need. Cruising boats don't need fast starts so there is time for the diesel to spool up and generate the thrust.
- If they had kept the video going you would have seen the diesel charge back across the screen
as the batteries quickly die and the diesel gets up into it's ideal power band and can keep it there for hours or even days.
- As far as powering into waves, the diesel would do much better than is implied here as it would be up in it's power band and putting out more thrust than the electric.
Electric will put out more torque off the line but after that, HP is torque times RPM
. If you want more torque, it's easy to add a reduction gear. They don't use lower reduction gears on diesels because that's not a key performance feature on cruising sailboats.
Put it in a car where you need a lot of torque to get the car moving and then very little HP to keep it moving and electric make a lot of sense. For a cruising boat, no one really cares about acceleration (wow, 0 to 6mph) max HP is needed at cruising speed (or slightly above to account for bashing into waves). As such the low end torque of an electric motor
isn't an advantage.