Maintaining and Replacing Your Propeller

March 17, 2015 - 1:02 PM by Samantha Pudney

Photo by Julie Mac, 2012 (CC-BY)

Photo by Julie Mac, 2012 (CC-BY)

A boat propeller is one of the most technical boat components. In order to ensure overall boat safety and optimal boat performance, it is critical to select the right propeller and take good care of it. Damaged or worn boat propellers can lead to a wide variety of serious issues including corrosion, cavitation, roughness, and surface damage, leading to further issues, reduced efficiency, and higher fuel consumption.

The following describes the procedures for maintaining and replacing your propeller.
You should inspect the boat propeller on a regular basis to check for nicks, bent blades, and rolled tips. Look at the blades, shafts, hubs, and seals. Are the boat prop blades worn out? Excessive wearing keeps the engine from accelerating past the normal range. If there is a part that needs to be replaced, get it switched out right away. Don’t take the boat out until you get a replacement part if you believe that it’s not safe to operate. Damaged boat propellers can result in cavitation as well as engine and sterndrive damage.

One of the biggest hazards for the prop shaft seals is fishing line. Stray fishing line, particularly braided line, can melt rapidly, turning into a sharp edged disc after it gets wrapped around the shaft. Then it slices into the seals. If you see signs of fishing line damage, have the seals replaced.

Check the boat propellers and the bottom of the boat for marine growth including grime, moss, aquatic weeds, lime, and barnacles. Build-up can reduce the engine performance as much as 50 percent. Grease the propeller shaft as part of your regular maintenance routine. You should also grease a new shaft before you fit it into the prop. Select a waterproof product, such as 2-4-C grease, that is approved for marine use. Applying ample grease makes it easier to remove the wheel in the future, especially if the propeller and shaft are not made of the same materials.


Do you have an aluminum boat propeller like the Solas aluminum Alcup? Grease the torsion rods on the hub interior as well. Take off the plastic nut that keeps the bush kit in place in the propeller’s center. Keep in mind that this is a left-handed thread. Take off the bush kit and grease the springs. Put the propeller back together, taking care not to over tighten the retaining nut.

Do you have a stainless steel propeller? These propellers are highly susceptible to corrosion and discoloration. To minimise these issues, select a spray product that provides a clear protective film coating for the metal, such as Quicksilver’s Corrosion Guard.

You should always keep a spare boat propeller on board just as you keep a spare tire in your car. Having a spare can mean the difference between getting a boat home safely and being stranded out on the water for an extended period of time. Keeping a spare on hand also ensures that you always have one handy in the event that your current propeller is getting repaired. Most boat dealers and propeller repair shops have boat propellers. Before the start of a new boating season, check for a spare and purchase a new one if you don’t already have one on board.

Running a boat with a damaged propeller for a long stretch can lead to a host of problems, including sterndrive or engine damage. If you believe that there is something wrong with the propeller but don’t see any obvious signs of damage, keep an eye out for loss of speed, vibration, loss of power, poor fuel economy, and noticeable slipping or cavitation while you’re operating the boat.
If you’re ever in doubt about any aspect of propeller maintenance or you’re not sure whether or not it’s time to replace your propeller, talk to a professional repairman. You don’t want a minor problem to spiral out of control. You also don’t want to further damage your boat by trying to fix a problem that is well beyond your level of expertise. It is better to be safe than sorry and get the professional help that you need to ensure maximum boat performance and efficiency.

You should also schedule a once yearly service check up. Regular maintenance with a certified technician ensures that someone is keeping an eye out for potential issues. A repairman may spot a small issue that you can fix now before it turns into a major, costly problem. The money that you save on large repairs will be well worth the cost of the annual check-ups.