How much thrust for my Scanoe?

Discussion in 'Boat Tips' started by topjimmy, May 7, 2006.

  1. topjimmy

    topjimmy New Member

    I have a 16 foot scanoe, I am going to put an electric motor on it. How much thrust should I get? Does anyone have advice for selecting shaft length? TIA.
  2. topjimmy

    topjimmy New Member

    How much thrust do I need?

    In general you want to have as much thrust as possible for the times when you run into wind and current. The rule of thumb in choosing thrust is to take the total weight of the loaded boat and divide it by 70. For example, if your boat with people and gear weighs a total of 3500 lbs you will then divide that by 70. That means that ideally you should have a motor with at least 50 lbs. of thrust.

    Motor Thrust Total Weight
    30 lbs 2100 lbs
    36 lbs 2520 lbs
    40 lbs 2800 lbs
    42 lbs 2940 lbs
    44 lbs 3080 lbs
    48 lbs 3360 lbs
    50 lbs 3500 lbs
    55 lbs 3850 lbs
    65 lbs 4550 lbs
    74 lbs 5180 lbs
    101 lbs 7070 lbs

    What length of shaft do I need?

    First, that depends on whether you want a transom mounted motor or a bow mounted motor. If you go with a transom mounted motor then you need to know the distance from the transom to the waterline when your boat is loaded. You want to take that distance and add at least 20 inches to it. If there isn't a shaft in that size then round up. Let's say the distance is from the transom to the waterline is 10 inches. You then add 20 inches to that and the length of shaft you want is 30 inches.

    If you want a bow mounted motor then you take the length from the top of the bow (where the motor would be mounted) to the waterline when the boat is loaded. You then add 20 inches to that number and then round up to the next longest shaft if you have to. So, if the distance from the bow to the water is 15 inches then you will add 20 inches to that. You come up with 35 inches but find that there is no motor for the brand you want with a 35 inch shaft. Therefore, all you have to do is round up to the 36 inch shaft. Simple, right?

    Bow to Waterline Shaft Length
    0-10 inches 30 inches
    11-16 inches 36 inches
    17-22 inches 42 inches
    23-30 inches 50 inches
    31-34 inches 54 inches