electric trolling motors

[joeh]

hi all
i note these are rated like thrust 54 ( pounds ?) at 12 V. how is this number convertible to kW or HP ? anyone ? ta

 

[Clyde_Wanderer]

Not sure, but I wouldent advice buying one to use on an inflatable dingy as they arent really powerfull enough.
I used mine on a 2.7m inf a few times and ended up buying a new outboard. although for a 14-17ft grp fishing boat my 56lb thrust could push them along no bother, and on a few occasions even towed another 14ft with three people in it no problem, better using a 110ah deep cycle batt, Heavy though.

 

[DaveS]

There isn't a direct relationship between thrust and power since that depends on the propeller. A more useful parameter is the maximum current draw which, multiplied by 12, gives the power in watts. A straight comparison using this will show an electric drive as apparently very feeble, but this is a bit misleading.

FWIW, my Minn Cota is rated at 30 lb thrust, draws 30A at full speed and feels, subjectively, like it pushes the dinghy about half as well as a 2.3 hp petrol motor would, i.e. about twice as well as the theoretical comparison would suggest.

 

[cpedw]

(Horse) power is thrust times speed. 1 horsepower is 550 ft lbs/sec. But I don't think that's much help. DaveS's observation relating volts times amps to kW is more apposite; and while an internal combustion outboard's rated output is rarely achieved and there are losses of several sorts, almost all of the volts times amps will be transferred to the propellor in an electric outboard.
I came across this electric outboard with integral lithium battery which sounds interesting - the lead battery handling is what has put me off an electric outboard so far.

Derek

 

[Evadne]

The above assessments of kw vs thrust need no further elaboration, really, except to confirm that it is not helpful to compare the poower output with that of an internal combustion engine, the efficiency at different throttle settings and the power delivery are not the same. I use a 24lb thrust motor to get my rigid tender out to the mooring and back, it's a bit feeble but faster than rowing. A 60Ah leisure battery gives one or two hours at full "throttle", there is no question of using lesser power settings. 36lb or more would be better, although the battery would not last as long. The lead acid battery is definitely a major handicap, don't even think about it in an inflatable tender without a rigid floor, as well as the usual electrical supply problems. There are some Lithium powered motors around, I saw the Torqueedo one at LIBS last year and it looked well engineered, and the battery is manageable but they are still very expensive, even by yachtie standards.

 

[Tekkie]

FWIW, One Horse power = 745.69987158227022 W

Brian

 

[pvb]

[ QUOTE ]
FWIW, One Horse power = 745.69987158227022 W

[/ QUOTE ]
Approximately! /forums/images/graemlins/tongue.gif

 

[Tekkie]

[ QUOTE ]
[ QUOTE ]
FWIW, One Horse power = 745.69987158227022 W

[/ QUOTE ]
Approximately! /forums/images/graemlins/tongue.gif

[/ QUOTE ]

Yep very!!! /forums/images/graemlins/cool.gif