How to balance an RC boat prop

Written by steven douglas
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How to balance an RC boat prop
Learn to balance your propeller. (old propeller image by Dimitar Atanasov from

RC (radio controlled) boat propellers (props) in most models spin at the exact same RPM as the electric (or gas) motor. Vibration from the propeller is the result of the propeller not being completely balanced with respect to its horizontal shaft. Each time the propeller spins, stress is momentarily placed on the propeller shaft in the direction of the "heavy" side of the propeller. This stress (back and forth repeatedly with each propeller revolution) will reduce the speed of the propeller and ruin delicate electronic parts. Balancing your propeller is easy and quick to do, and will eliminate this phenomenon.

Skill level:

Things you need

  • RC boat propeller
  • Eye protection
  • 220 grit wet/dry sandpaper
  • Small hand file
  • Dry erase marker
  • Paper clip
  • Clean dry rag

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  1. 1

    Remove the RC boat propeller from the vehicle, and clean it thoroughly so that is clean, dry and has no visible contaminants. Make certain that the propeller "hole" is clean. Inspect the prop visually and by feeling with your fingers for any bumps or deep scratches. Make note of these areas, because they may be the reason for any propeller vibration.

  2. 2

    Straighten the outermost loop of the paper clip so that it sticks out from the other loops at a 90-degree angle. The angle is correct when you can comfortably hold the paper clip in one hand, and the bent portion sticks out horizontally to the ground.

  3. 3

    Hold the paper clip in one hand, and stick the propeller onto the horizontal portion of the paper clip (paper clip goes into the hole in the centre of the propeller). It should be placed so that it does not touch any other part of the paper clip, and is not in danger of falling off.

  4. 4

    Put on eye protection. Spin the propeller gently without dislodging it from the paper clip. When the propeller stops moving, mark the lowest portion of the propeller blade to the ground with a small dot using the dry erase marker.

  5. 5

    Repeat the spin and mark sequence several times. You will note an area of the propeller that has many marker dots on it. This side of the propeller is heavier than the side directly opposite. Use the hand file to gently smooth the contours of the heavy side of the propeller, making sure not to alter its design shape. The goal is to remove just a slight bit of material, thus decreasing the weight on that side of the propeller.

  6. 6

    Wipe off the dry eraser dots, and begin again with the spin and mark sequence. When filing the heavy side spots, remember that just a few strokes with the file should remove enough material to change the balance of the propeller. Repeat this sequence until there is no discernible pattern to the dry erase dots. This means the propeller is relatively balanced on all sides.

  7. 7

    Finish the balancing procedure by lightly sharpening all blade edges of the propeller with sandpaper. The goal is to sharpen the blades without removing much material. If done uniformly across all the blades, there will be no alteration in the propeller's balance.

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