How to Remove and Replace an Outboard Propeller

Whether you want to swap propellers, replace a damaged one, inspect the oil seals or remove debris, replacing an outboard propeller is pretty simple. No special tools are needed to get the job done. 

Typical toolbox items such as a ratchet and sockets, screwdrivers and pliers will do. An outboard prop swap/reinstall can usually be done in a matter of minutes. Here’s how to remove and replace an outboard prop.

How to Remove an Outboard Prop

Step 1. Bend back the tabs on the lock-washer securing the propeller nut, or remove the cotter pin securing the castle nut. Next, remove the propeller nut or castle nut, and pull the prop off the shaft.

PRO TIP: Place a block of wood between the propeller’s blades and the ventilation plate to keep the prop from turning.

Step 2. Remove the thrust washer, then inspect it and replace it if it’s worn. 

NOTE: In the image above, the outboard's lower unit has been removed to make other repairs. You don't need to remove the lower unit from the outboard to get the propeller off.

With the prop and thrust washer removed, you can inspect the oil seal for wear and remove any debris such as old fishing line tangled around the prop shaft.

Replacing the propeller is basically reinstalling the parts that were removed in reverse order, but you should first lubricate the prop shaft with PTFE marine grease. 

How to Install an Outboard Propeller

Step 1. Reinstall the thrust washer, then install the new propeller or reinstall the one you have.

Step 2. Reinstall the lock-washer and prop nut, or the castle nut, and torque the nut according to the manufacturer’s specifications. 

Step 3. Bend the tabs on the lock-washer back over the propeller nut, or reinstall the cotter pin to secure the propeller castle nut.

If you’re looking to buy a new propeller but not sure what the correct size prop to get, watch the video below to learn how to find prop size dimensions.