Boat Rigging Part 10: Prop Installation

Regular prop inspection and maintenance is fast and easy, and could prevent a major repair bill down the road.

An engine prop is a pretty important piece of equipment that often gets overlooked. Inspecting it for nicks that could eventually harm the engine and reduce efficiency is key. Also, periodically removing it to check for fishing line can help prevent a healthy bill from your boat dealer.

Depending on the type of hub kit you have, a few simple tools will be required.

  1. Large flat bladed screwdriver or needle nose piers depending on kit type.

  2. Lubrication such as Mercury 2-4-C with Teflon.
  3. Disposable rubber glove.
  4. Heavy work gloves and a block of wood.
  5. 1/2-inch deep drive socket with extension and deep well socket. (most nuts are 1-1/16-inch)

First make sure that you have the proper hub kit. Depending on hub type the parts may be slightly different from the Flo Torq II on my Mercury Pro XS and Bravo prop.

  1. Clean off the prop shaft and use a product such as Mercury 2-4-C to cover the prop shaft, keeping the threads free of any lubrication.
  2. Place a large washer/spacer on the shaft. Most hub kits have instructions with pictures that will explain what side goes on first.
  3. Place the large poly hub piece on the forward part of the prop with the small holes facing outward. In most cases it can only fit one way and will remain flush.
  4. Place the metal housing hub from the backside of the prop so that it fits flush.
  5. Hold the hub parts so they don’t fall out and gently slide the prop onto the prop shaft. A slight jiggle is often necessary to get all of the parts to line up. DO NOT force it onto the shaft.
  6. Place the small key onto the prop shaft and line it up on both sides so it cannot rotate.
  7. Hand thread the large nyloc nut onto the shaft to avoid cross treading.
  8. Use a 1/2-inch drive socket instead of a plastic style wrench to tighten the nut. Gloves and a block of wood are helpful to avoid serious hand cuts from the sharp prop edges. A torque wrench tightened to the manufactures specs is even better.
  9. Tighten the prop nut so that the flaps on the key can be pushed on the flat side of the nut.

  10. Make sure there is no wobble in the shaft. Kits are meant to go on one way and you will know if you did it wrong.

Knowing how to properly and quickly change a prop is a skill that will come in very handy, especially if you’re in a pinch out on the lake. Routine inspections will greatly reduce the chances of damage occurring.

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Capt. Ross Robertson

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