Electric versus gasoline outboards ?

[Externet]

Hi all.

Two identical boats laden with the same weight, outboard engines; if one engine head is replaced with an electric motor, and both equal propellers at the same gear/rpm, how they compare their thrust forces in Kilowatts against horsepower developed; in several conditions as tied to a pier, at 10 km/h, 20 km/h, full throttle... ?

 

How to reasonably accurately do a equivalent calculation/comparison ; as to say a 'x' number of electric kilowatts match 'y' number of horsepower ?

 

The horsepower ratings are typically af full throttle/ideal conditions on marketing papers, but; is there a way to state something like 3 gasoline horsepower =~ 1 electric horsepower ?

[Acme]

http://www.engineeringtoolbox.com/electrical-motor-horsepower-d_653.html

 

Electrical power is in general rated in Watts or Horsepower. A horsepower is a unit of power equal to 746 watts or 33,000 lb.ft per minute (or 550 lb.ft per second).

 

A watt is a unit of measure equal to the power produced by a current of 1 amp across the potential difference of 1 volt. A watt is 1/746 of 1 horsepower.

...

[Externet]

Yes, 1 HP has always been 746 W.

[Acme]

Yes, 1 HP has always been 746 W.

No, it has not. Watt invented the term 'horsepower' in 1782, but the term 'watt' wasn't adopted as a unit of power until 100 years later. Arguably 746 watts may have always been 1 horsepower, but not the other way 'round.

[Acme]

Errors and ambiguities aside, electric drag boats have been around for a number of years.

 

http://www.seattleoutboard.org/electric.html

Seattle Outboard Association first branched out into Electric Boat Racing when it was the APBA-affiliated sanctioning body for a World Kilometer Record Trial, Sponsored by an Everett WA electric utility in 1992. The kilometer record at that time was 50.8 mph, held by Britain's Fiona, Countess of Arran.

...

E-boat races are flag-started heats of two laps. The focus is on fast starts and using all available power within those two laps. currently, a 144v hydro can accelerate from start to 70 mph in approximately 300 feet, and E-boats can race flat out for distances up to 3 miles per charge. Close racing is common within classes. As an example, the 1996 championship for 144v was decided by a mere 113 points.

 

To describe the boats: 144s run 12 automotive starter batteries to provide 144v at up to 800 amps. Motors are 36 to 48 volt industrial DC or aircraft starter motors used as powerheads on outboard lower units. When powered as noted, the higher current "hot-rods" these motors to nearly 155 horsepower. 48s use only 4 batteries, and these pump 12 to 30 volt motors to about 20 horsepower. Hulls for both classes are usually converted existing raceboats, though larger (up to 14 ft.) custom hydroplanes prevail in the 144v class providing extra lift for battery weight.

 

If you're interested in getting involved in E-Boats, we have available raceboats and we'd welcome your company. For more information on electric boats, write or call:

 

John Paramore

914 210th PL SW

Lynnwood, WA 98036

Phone/Fax: 206/672-2757

E-mail:wizprodj@eskimo.com

Now you know the rest of the story.

[Enthalpy]

I don't see why kW should be stronger or weaker depending on the motor's nature - unless manufacturers cheat, of course.

 

An electric motor running slowly, say 10m/s as most do around is, is slightly heavier than a petrol engine. But if it can run quickly, like 100m/s, then it's as light as a gas turbine, and more compact. For instance the turbo-alternator of a 1300MW power plant is the tiny thing at the end of the shaft, after the huge turbines.

http://en.wikipedia.org/wiki/File:Turbogenerator01.jpg (the red thing)

Edited February 6, 2014 by Enthalpy