Outboard HP = electric lb thrust ?

Discussion in 'Boat Tips' started by cjb10876, Mar 20, 2006.

  1. cjb10876

    cjb10876 New Member

    Messages:
    59
    State:
    Pennsylvania
    I just got my first boat,a 14' aluminum V. it's a 1970 Grumman. It came with an old Minnkota electric, but no gas motor. That's not to big a deal, since a lot of the local fishing holes are electric only or limited to 9.9 hp. I would like to get in the rivers eventualy, but for now i just want to get it in the water.

    Here is my question. Does anyone know if there is a comparison for how many lbs of thrust a given HP gas motor would put out? Any idea where I could find one?

    For example, would a 2hp gas motor equal a 40lb thrust electric? I had been considering the 5hp Briggs and Stratton outboard for the "larger" lakes or the river, but would I be better off with a med/large electric if it would put out similar thrust and be able to use it on more waters?
     
  2. hodx

    hodx New Member

    Messages:
    16
    State:
    diz
    50.lb thrust = 1 hp..........a 2hp gas =100.lb thrust electric motor...herman
     

  3. cook

    cook New Member

    Messages:
    1,494
    State:
    Plattsburg,Mo.(near K.C.)
    I've been asking that question for years and never got a decent answer.
    The best explanation I got was from a dealer,and it was a non-answer:confused: he said thust is more equal to torque,horsepower is equal to voltage/wattage.the way he went on to explain it made sense at the time
     
  4. dademoss

    dademoss Member

    Messages:
    524
    State:
    Ohio
  5. Mark J

    Mark J New Member

    Messages:
    9,407
    State:
    Four Oaks, NC
    Thrust doesnt convert to horsepower but any electric motor has a horsepower rating whether it shows on a name plate or not.
    That horsepower rating isnt going to compare to a gas horsepower rating either because of the prop pitches and diameters.
     
  6. solomon

    solomon New Member

    Messages:
    735
    State:
    MS
    You can convert thrust to horsepower, but there are a couple of factors. Power = (force x velocity), so it would actually change depending on how fast your going. The velocity has to be a constant for a given horsepower. Then you also have to think that a different speeds, the thrust is probably going to vary, ie. less at higher speeds maybe? I think that's why hosepower ratings for outboard motors for instance are given at a certain rpm. Someone correct me if I'm wrong.
     
  7. hodx

    hodx New Member

    Messages:
    16
    State:
    diz
    I did contact minn-kota...they gave me an answer, like this about boat weight and thrust....they said I needed 26.lbs thrust for each 100.lbs of boat weight.My first boat weight 600.lbs...which means I needed 165.lbs thrust..I pushed that boat in high 20mph winds in open water using only 2 batterys and 55.lb thrust motor.....I checked my gps while running it...it posted a speed of 1.3mph with calm conditions,no wind...so thats where I came up with 50.lbs thrust=1hp.....one company sells a 3hp electric and specs say 150.lb thrust...so 50.lb thrust=1hp seems reasonable......Herman
     
  8. Bypass

    Bypass New Member

    Messages:
    10
    State:
    Georgia
    The rule of thumb I go by is 1 HP = About 22 lbs of thrust. So it's about 55 lbs of thrust for 2.5 HP.
     
  9. Dukslayr

    Dukslayr New Member

    Messages:
    631
    State:
    Liberty, Missou
    The other thing to really consider here is how far you're going to be running and how many batteries you want to deal with. I used to duck hunt 3-4 days a week and I thought it would be a great idea to go with an electric motor on my layout (wide, shallow boat). After one season I ditched that idea, went with a gas motor and never looked back. Not having to deal with extra batteries, particularly if you have to lug them in and out of the boat to charge them and such, was worth its weight in gold. I know my boat with a 3 hp outboard moved a hell of a lot faster than when I had the 75# thrust trolling motor on it.

    If you go with anything over 40 lb thrust, you're really going to have to consider going with a 24v system or at least taking multiple batteries if you plan on being on the water for very long. The nice thing about a small outboard is that they're pretty low maintenance and you can throw a little jug/tank of fuel in and run for days. Just a thought.

    Thomas
     
  10. catfishscotty

    catfishscotty Well-Known Member

    Messages:
    4,388
    State:
    mo
    I had a transom mount 12 volt 50 lb thrust trolling motor on my 2 man bass boat and 14 foot john and it did great on the 150 acre to 600 acre lakes I bassed fished in and would last all day with no problems at all .


    but trust me on this 1 if your planning on fishing in rivers no dought about it I would go with a 9.9 hp motor the reason I say 9.9 is they made so many of them in so many brands if you watch around you should be able to buy 1 for the same price as a 5 hp or 7.5 hp .


    tons and tons of good used 9.9 motors . alot with electric start also ,, so then ya could get a nice litle fish finder and hook it to your battery for the motor .

    also a 12 volt transom mount trolling motor is pretty cheap compared to foot countroll .


    just my 2 cents and congrats on getting the boat your gonna enjoy it and good luck !!!!!