Mercury Marine has implemented a new, industry-first dynamic balancing process for all of its mass-produced stainless-steel propellers that will result in perfect balance while preserving the engineered shape of the blades. A prop that is in perfect balance will not produce a vibration that could diminish the boating experience.

Much the way an automobile wheel is balanced by adding small weights to the rim, Mercury will gauge the prop balance by rotating it at high speed, and then when required add a small weight to the inside of the hub to balance the propeller. In the past stainless-steel props have been balanced using a process that requires grinding away small amounts of material from the propeller blades, which changes the shape of the blade slightly.

Like vehicle tires, wheels and other manufactured products meant to rotate at high speeds, propellers are manufactured to be nearly perfectly balanced. However, slight variations in manufacturing can create an out-of-balance condition that should be corrected. The new balance-by addition process will correct any imbalance while keeping blade shape and size consistent. The added weight is made of corrosion-resistant stainless steel and will not affect the look of the propeller because it is attached inside the hub. The weight is secured with 3M™ VHB™ tape, which is designed to withstand the harshest environments, including hot, cold, cycling hot and cold, UV light, moisture, and exposure to solvents. Removing the weight is nearly impossible once the adhesive has cured for 24 hours.

Many Mercury props are cast to a nearly perfect balanced condition, so balancing is not always required and not all stainless-steel props will have a balance weight. Others might require two small weights to achieve perfect balance. And two props of the same model and size may have different weights so that each is perfectly balanced. If the prop is damaged in use and needs to be reworked it can be rebalanced through traditional methods with the weight attached. The weight is not designed to be removed. In the highly unlikely event, the weight becomes detached it may not be necessary to take any immediate action if no vibration is detected. However, taking the prop to a prop-repair business for traditional balancing is always an option. An aluminum prop does not require balancing because it has much less mass than a stainless-steel propeller.

*Still have questions? Check out the Balance by Addition FAQs below.

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Balance by Addition FAQs

What is balance-by-addition?

Upcoming innovations planned for Mercury Propellers include implementation of the industry’s first balance-by-addition process that dynamically balances stainless-steel propellers, rather than utilizing traditional static balancing. That means Mercury will add weight to the inside of the propeller hub to perfectly balance propellers, ensuring they retain their engineered characteristics and provide the high performance you expect from all Mercury propellers.

Balance-by-addition Features

• Perfect Balance. Mercury will dynamically and perfectly balance mass-produced propellers by adding weight for the best NVH (Noise, Vibration and Harshness) experience possible.
• Blade Design Maintained. Perfectly balancing props by adding weight eliminates the need to grind away material from a highly engineered and carefully cast propeller blade.
• Consistency. Mercury can mass produce nearly identical propellers by using the balance-by-addition process. Blade size and shape are more consistent, delivering more consistent performance directly out of the propeller box.

Why is Mercury changing the way it manufactures stainless-steel propellers?

Mercury constantly strives to update and improve its manufacturing processes to deliver the best products in the industry, including its propellers. The addition of “balance-by-addition” results in the highest-quality stainless-steel propellers.

Will the weight fall off?

Removing the weight is nearly impossible once the adhesive has fully cured (about 24 hours after being applied). The weight is attached with 3M™VHB™ tape, which is designed to work in all environments, including hot, cold, cycling hot and cold, UV light, moisture, and with exposure to solvents.

Aren’t propellers perfectly balanced when they are cast? Why do they need balancing?

Like vehicle tires, wheels and other manufactured products meant to rotate at high speeds, props are manufactured to be nearly perfectly balanced. However, slight variations in manufacturing can create an out-of-balance condition that must be corrected to ensure a satisfying user experience – whether it’s the propeller on your boat or the wheels and tires on your car or truck. Adding weight as necessary ensures every Mercury stainless-steel prop is perfectly balanced.

Are propellers produced with balance-by-addition better balanced than other props?

Every Mercury prop is designed not to produce noticeable vibration on your boat. The new balance-by-addition process allows balancing to perfection without excessive grinding of a highly engineered prop blade. 

My propeller doesn’t have an added weight. Should it?

Not necessarily. Many Mercury props are cast to a nearly perfect balanced condition, so balancing is not always required.

My propeller has two added weights. Should it?

If weight can’t be added at the ideal location on the prop, two weights may be added in an alternative location to perfectly balance the prop.

My propeller originally had an added weight but now it doesn’t. What should I do?

In the highly unlikely event the weight on your prop becomes detached you may not need to take any immediate action if no vibration is detected. However, taking the prop to your nearest prop-repair business for traditional balancing is always an option.

If I damage my prop and have it reworked, what happens to the added weight?

The weight is not designed to be removed. The prop can be rebalanced through traditional methods with the weight attached.

What is the weight made of? Will it rust or cause other corrosion issues?

The added weight is made of stainless steel, just like your prop. The added weight does not affect the highly polished look you expect.

Why does the added weight stick out so far? Could it be hidden in the hub area?

The added weight is placed in a location that is best for proper balance, uninhibited exhaust flow, and proper adhesion to the prop.

My aluminum propeller does not have an added weight; is it balanced as well as my stainless-steel propeller?

The mass of an aluminum propeller is not large enough to require balancing.

How does the added weight impact performance?

The added weight improves balance and will not negatively impact performance.

I have several propellers and they all have different amounts of weight. Is this correct?

Yes, and it is likely. Often, each propeller will have a different amount of balance weight required to perfectly balance.