How to Install a Boat Propeller Shaft

Written by robert morello Google
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A propeller shaft is a metal tube that acts as a driveshaft, delivering power from the engine to the blades and causing the boat to move. Prop shafts can become damaged if your boat bottoms out, becomes tangled in sea weed or due to operation in very rough seas. Depending on how badly damaged your propeller shaft is, the results can range from rough and bumpy propulsion to complete detachment with the prop.

Skill level:
Moderately Challenging

Things you need

  • Ratchet set
  • Breaker bar
  • Liquid lubricant
  • Marine grease
  • Flat head screwdriver
  • Pliers
  • Long screwdriver (over 12 inches)

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  1. 1

    Remove the boat from the water to access the propeller shaft. Inspect the propeller shaft for bends, damage or total detachment. To locate the prop shaft, find the propeller then look behind it for a long metal rod leading to the engine.

  2. 2

    Determine whether your propeller is held in place by a cottar pin or a lock washer. Look at the centre of the propeller where the prop bolt comes through. If you see a cottar pin, squeeze the barbed ends with a pliers to flatten them, then slide the pin out. If you see a lock washer, bend the raised teeth with a flat head screwdriver until the washer is all flat. Wedge a long screwdriver into the blades and against the body of the outdrive to prevent the prop from spinning. Use your ratchet to turn the propeller nut counterclockwise until loose. Remove the propeller.

  3. 3

    Follow the shaft up to the point where it attaches to the transmission. Remove the set screws located on the side of the shaft near the transmission. These screws hold the shaft in place and keep it from detaching from the rest of the drivetrain. There are typically one or two, but there can be as many as four depending on the type of engine and linkage. With these screws removed, the shaft should slide out of the transmission coupling with a little work and some more lubricant.

  4. 4

    Purchase a propeller shaft appropriate for your model engine and linkage. Install the propeller shaft by sliding it into the transmission coupling. In most cases the shaft will have either two or four metal ears protruding from its end, as will the transmission coupling. Interlock these ears to create a tight connection, which will turn as one. Apply grease into the joint for smooth operation. Replace the set screws where they were on the side of the shaft. Replace the propeller after cleaning off any salt or debris.

Tips and warnings

  • If your propeller is damaged, now would be a good time to make a change.
  • As you work, apply a lubricating oil to all the screws and bolts you remove during the process. Rust, age and torque can tighten them significantly and cause them to be very difficult to remove.
  • Do not force the propeller shaft from the transmission linkage -- doing so can cause damage to the transmission and the housing.

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