Boat Propellers: Repairs & Replacement Guide

Your boat's propeller connects the engine to the water, just as tires connect your car to the road. Unlike tires, your propeller will not wear with use but is prone to damage, ranging from a few nicks in the blade edges to catastrophic damage from a severe bottom strike.

The soft propeller hub can also be damaged in a bottom strike or just from age. Even minor damage can impact boat performance, so taking good care of your propeller is essential.

How to Maintain Your Boat's Propeller

Complete regular inspections.
Repair or replace the prop when damaged or bent.
Replace the rubber or plastic hub between the propeller and prop shaft if needed.
Always carry a spare propeller onboard—just like a spare tire.
When in doubt, call in the professionals for assistance.

Boat Maintenance Guide

Regular Inspection

Get in the habit of inspecting your propeller during the boating season. With the transmission in neutral, you can turn the prop. Remember to always remove the engine kill switch before inspecting the propeller.

During your inspection, look for the following:

Bent blades or nicks in the leading edge.
If you don't see any obvious damage, carefully run your fingers along the leading edge of the prop blades to check for burring, which can occur if the prop is run through sand.

If you find any burrs, you can remove them yourself with a mill bastard file.

Boat Propeller Repair

If prop blades are bent or otherwise damaged, the prop should either be replaced or repaired. Consider the following:

Bent blades will prevent the prop from functioning correctly, negatively affecting boat performance.
A damaged prop is likely unbalanced, which can cause vibration at high speeds, leading to further issues.

A good propeller shop can restore a prop with significant damage, often by welding new material onto the affected blades and then grinding and shaping them back to their original geometry.

Repair costs typically include:

Aluminum prop repairs: $100 to $150
Stainless steel prop repairs: $200 to $400

While replacing a damaged aluminum prop may be more cost-effective, repairing a stainless steel prop often makes economic sense, especially since a new stainless prop can cost between $400 to $700. Prop repair requires special skills, tools, and experience, so most marine dealers have relationships with prop shops and send propellers out for service.

Additionally, any time you strike the bottom hard enough to damage the prop, you should have a dealer inspect the propeller shaft. The shaft must be repaired or replaced if it is bent.

Hub Damage

Most props have a rubber or plastic insert between the propeller and the prop shaft. This insert is designed to give way on a hard prop strike to protect the gearcase from shock—it's cheaper to replace the prop than the gearcase. If your boat does not move when you apply the throttle or only moves slowly, you may have "spun the hub."

It's important to remember the following regarding hub issues:

A prop shop can usually replace a spun rubber hub.
The plastic hub inserts used on many new props are simple to replace; you can carry a spare and replace the plastic insert yourself while on the water.
Rubber hubs will also deteriorate over time and may need to be replaced even if you don't strike bottom.

Always Carry a Spare

A spare prop is just like a spare tire—a replacement you can use in an emergency. If your prop is too severely damaged to get you home, replacing it is a viable alternative to getting towed back to shore. Many boaters buy a used prop of the correct size to carry as a spare. An affordable aluminum prop can serve as a backup to a stainless prop.

To ensure you're prepared, consider the following:

Carry a propeller wrench to remove the prop nut.
Bring a spare nut, thrust washer, and any other hardware required for prop replacement if you drop a part into the water.

Practice changing the prop in the marina or with the boat on a trailer so you know the procedure. Changing a prop at sea can be tricky if the water is rough; in such cases, it may be safer to call for a tow.

Are you looking for more information on boat maintenance and repairs? Check out these posts:

Activity:

Day Cruising