small electric motor 140watt, size of prop and speed

Discussion in 'Props' started by flowing, Nov 30, 2009.

  1. flowing
    Joined: Nov 2009
    Posts: 1
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    Location: nz

    flowing New Member

    Hi all.
    I'm trying to build a small boat, but i'm not to shore of the power requirements. I would like the boat to beable to go over waves.
    I'm guessing the weight of the boat to be about 5kg - 10kg.
    The motor that I think might beable to move it out to sea is a 12volt 14amp max at 160rpm and 50kg/cm torque. Hydrodynamics of the boat should be quiet low(if you need I will try to find this info)

    I would like to hear from you lot weather the motor fitted to a average to good prop would beable to move the boat over the waves.

    Thanks for you time.
  2. Amp User
    Joined: Jul 2006
    Posts: 36
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    Location: Texas

    Amp User Junior Member

    Input Power Watts: 1,000
    Output Power: 480 Watts (Comparable to 3 HP gas outboard)
    Static Thrust: 68lbs.
    Battery Output: 400 Watt Hours
    Integrated Battery: Lithium-Manganese (13Ah@29.6V)
    Steering Type: Twist tiller
    Gearing: F-R continuously variable
    Prop Size: 12" x 10"
    Weight: 28lb.
  3. Amp User
    Joined: Jul 2006
    Posts: 36
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Texas

    Amp User Junior Member

    Specifications: Input power in watts

    Rated voltage in volts

    Final voltage in volts

    Propulsive power in watts

    Comparable gas outboards
    (propulsive power)
    1 hp

    Comparable gas outboards (thrust)
    2 hp

    Maximum overall efficiency in %

    Static thrust in lbs

    Total weight in lbs

    Weight of motor without battery in lbs

    Weight of integrated battery in lbs

    Shaft length in inches

    Integrated battery
    230 Wh LIMA

    Propeller dimensions in inches
    8 x 8

    Propeller speed at full power in rpm
    max. 1,200

    Remote throttle control

    Provision for connection to kayak rudder; lockable

    Tilting device
    manual with grounding protection

    Stepless forward/reverse drive

  4. Guest625101138

    Guest625101138 Previous Member

    The boat in the linked clip is quite a bit heavier than you are planning. Total weight is around 110kg:
    The motor was working up to 200W in the video to get 11kph. It will do about 8kph with 140W. The motor is a model aircraft motor weighing 59g with a 12:1 reduction spinning a 15 X 12 model aircraft prop. The motor is rated around 600W but would not do that for very long.

    You should have no trouble achieving planing speed with a 5 to 10kg boat using 140W. 160rpm is quite slow though. A prop pitched to get the speed potential would be unusual for the size of boat.

    How fast were you hoping to get it up to?

    Rick W
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