What is Thrust?

[tee-boy]

What exactly is Thrust? Is there a correlation b/w thrust and horsepower of the electric motor? It seems odd to me that the same manufacturer can produce two 53lb thrust motors but one is a 12v motor and other is 24v motor.

 

[JB]

Re: What is Thrust?

Thrust is the amount of forward push a motor can generate, Tee-Boy.<br /><br />The advantage of the 24V is that it uses only half as much current to make the thrust, so 2 batteries last twice as long as one.<br /><br />Lots of folks want to measure electric motor thrust in HP. That would be counterproductive. Thrust is a much more valid way to measure what a motor can do with a particular prop.

 

[jajeeper]

Re: What is Thrust?

Here is what Minn Kota's website has to say about it:<br /><br />What is thrust?<br /><br />Thrust is a static measurement in pounds of our motors pushing or pulling power. <br />Minn Kota’s published thrust ratings are laboratory measurements taken by using a load cell and with voltage equivalent to a fully charged battery (or batteries) applied directly at the motor brushes. <br />How does thrust compare to horsepower?<br /><br />Horsepower is a measurement of “work” being performed. <br />One horsepower is a unit of measurement equal to 550 foot pounds of “work” per second. <br />There is no direct correlation of thrust to horsepower. Contrary to what you may have been told, fifteen pounds of thrust DOES NOT equal one horsepower. <br />As noted in the previous definition, thrust is simply a static measurement of force. <br />How does thrust compare to speed?<br /><br />“My buddy has a 36 lb thrust motor, we have the same size boat yet his motor moves his boat just as fast as my 42 lb thrust unit. Why is this?”<br /><br />Again, thrust is simply a static measurement of pushing or pulling power, and higher thrust does not necessarily mean greater speed. <br />Speed is a factor of prop pitch and motor R.P.M. <br />Given motor R.P.M. under load, and Minn Kota’s 4" prop pitch, the approximate speed that a motor will push/pull a small boat can be calculated. <br />The formula for this is: <br /> .85 (4x) x 60 = Miles Per Hour<br /> 12 5280 (Motor RPM = X) <br /> <br /><br />How do I convert thrust into horsepower?<br /><br />Many people think that the more pounds of thrust they are getting, the faster the boat will go. This is not exactly true. With trolling motors and outboard motors, boat speed (and acceleration) depends on horsepower and prop pitch. By changing prop pitch, you can trade acceleration for top speed. Our trolling motors have props designed for maximum acceleration. When you hit the power, the boat responds immediately. This also allows you to hold the boat in high wind conditions. Top speed with our motors and props is about 5 mph. Small boats will reach this speed with most of our motors. Larger boats require our largest motors to approach this speed. Comparing our motors to gasoline outboards is difficult because most outboard props are designed for much higher speed.