T-Pain Is On A Boat: [Electric Boats] Re: Electric power for over 30' [Question for Dave K]

Monday, June 1, 2009

[Electric Boats] Re: Electric power for over 30' [Question for Dave K]

--- In electricboats@yahoogroups.com, iloveamercedes@... wrote:
>
> Hey Dave, I am intrigued at the prospect that a rated 8 hp electric motor
> can have the same pulling power as a 'rated' 50 hp Diesel motor!
> Now I may not understand what "Bollard Pull" is...

I'm going to comment on this as I have some real world numbers that I have measured on outboards for bollard pulls.

300 lbs of thrust is very minimal.. it is about the equivalent of a 9 to 12 hp outboard..

I have tested 4 hp engines and they get in the neighborhood of 120 lbs of thrust in a bollard test. 6 hp engines should get in the neighborhood of 160 lbs of thrust.

bollard tests are very much affected by size and pitch of prop also.

all the testing I did used a inline load cell rated accurate to + - 1 lb from 1 lb to 3000 lbs. The numbers I got were reflective of industry standards (in other words reflective of what published numbers for that horsepower range were)

So the end result is that 300lbs of thrust is nowhere near what a 50 hp diesel engine should have been able to produce. If you were not getting but 300lbs of thrust out of your diesel then it was in sad shape or badly mispropped.