MerCruiser Propping FAQs

How can I find my closest authorized MerCruiser dealer?

Authorized MerCruiser dealers in the United States and Canada can be found under Find a Dealer on this website.

Links to regions outside of the United States and Canada can be found on the Contact Us page.

What's the best propeller for my MerCruiser?

Your engine should be propped so that it operates at or near the top end of its recommended rpm range at wide open throttle with a normal boatload (fuel, gear, people, etc.) An engine that does not reach the rated RPM at wide-open-throttle is in an "overpropped" condition, resulting in "lugging the engine." This high-torque operation puts a tremendous load on the pistons, crankshaft, and bearings in your marine engine.

On the other hand, an engine that revs past the recommended RPM will have higher than normal wear and can also be damaged.

Propping is not an exact science and may require some trial and error. The maximum RPM your engine can achieve is dictated by propeller pitch. Generally speaking, one inch of propeller pitch equals 150-200RPM. To increase your engine RPM, you should decrease propeller pitch and vice versa. Your local authorized dealer can assist you in choosing the best propeller.

Initially, the prop on your boat is selected by the boat manufacturer and/or selling dealer. However, the way you load your boat (people, fuel, gear, etc.) may indicate that a different prop is best for your use. Please notify your dealer immediately if your engine cannot reach the proper rpms at wide-open throttle.

You may visit the Propellers section of this site for additional information.

What are the differences between aluminum and stainless steel propellers?

Aluminum is by far the most popular material used today for recreational boat propellers. It is relatively low in cost, has good strength, good corrosion resistance, and is easily repaired. However, compared to stainless steel propellers, aluminum propellers are more easily nicked or bent. Stainless steel is the strongest, most durable of all materials used for propellers. In fact it is about five times stronger than aluminum. This is its greatest advantage. The strength of stainless steel propellers will help maintain engine performance because these propellers are more resistant to the small nicks and bends normally found on aluminum propellers, often after running for a short period of time. Blades cast of stainless steel can be made thinner for better efficiency. Stainless steel is much more resistant to corrosion. Stainless props can be repaired easily, although more expensively than aluminum. They can cause some corrosion on nearby aluminum surfaces in saltwater if good anodic protection is not used. An aluminum propeller can usually be replaced with the nearest size and blade equivalent stainless steel propeller.

What is the difference between 3-blade and 4-blade propellers?

4-blade propellers:

  • Plane the boat faster than 3-blade propellers 
  • Keep the boat on plane at a lower speed 
  • Give improved mid-range speed at the same rpm as a 3-blade propeller 
  • Provide quicker acceleration than most 3-blade propellers 
  • Run smoother than 3-blade propellers 
  • Have better holding power in rough conditions 
  • Are less likely to ventilate in sharp turns 
  • Provide better low-speed handling 
  • Are usually not quite as fast on the top end as a comparable 3-blade propeller

You may visit the Propellers section of this site for additional information.

What is the best prop for skiing?

Designed with sterndrive ski boats in mind, the HighFive delivers unsurpassed hole shot, good top-end speed, better bow lift and handling, reduced vibration, and great holding in rough water. You may visit the Propellers section of this site for additional information.

How can I improve hole-shot and top speed performance?

No single propeller can deliver both optimum hole-shot and top speed performance, with the exception of the Enertia. You will need to decide which of these performance aspects is more important to you and select a propeller that is best suited for that purpose. You may visit the Propellers section of this site for additional information on the Enertia and all other propellers.

My stainless steel propeller is turning white, or is rusting or discolored. What can I do about this?

Stainless steel propellers can discolor and form areas of light rust. Brushed finish stainless props are more susceptible than brightly finished stainless steel props. Rust stains can occur from polluted water, galvanic corrosion from the boat or marina, or from oxygen depletion. The propeller can be easily cleaned with rubbing compound or Scotchbrite. Do not use steel wool. After cleaning, use chrome polish to protect the finish. Stainless steel props can also turn white from calcium or lime in the water. In this case, clean the prop with household mineral bath and tile cleaner. Again, do not use steel wool. Follow up with chrome polish to protect the finish.

How can I prevent the propeller from sticking onto the shaft?

We recommend a liberal coat of one of the following Mercury Precision or Quicksilver Marine Lubricants on the propeller shaft: Special Lubricant 101, 2-4-C Marine Lubricant, or Anti-Corrosion Grease. These lubricants are available from any authorized Mercury Marine dealer.

Note: Always use the correct mounting hardware and torque the propeller nut to the correct specifications. Verify the propeller tightness after 20 hours of operation. DO NOT operate the boat with a loose propeller.