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How to Know if You Have the Right Motor Propeller

Your boat’s propeller makes it go. But depending on where or how you “go”, the prop you have may not be the best fit. Here are some basics to consider.

The Material It’s Made Of

Today’s propellers are most commonly made of aluminum or stainless steel. But there are pros and cons to each.

Aluminum ranks in the affordability category and is a fine material for smaller outboards. But with aluminum, you give up performance and durability. Propellers made from aluminum tend to flex more with a load. Consequently, you may give up some speed with an aluminum prop.

More common is stainless steel props. Stainless steel offers more durability and retains shape under a load. This offers much better performance. The disadvantage? Many people worry that if something is hit with a stainless steel prop that it can damage the engine’s gear case. But both aluminum and stainless props have a central hub designed to break away in this case. When breakaway occurs, the aluminum prop will sustain more damage than the stainless steel. If you’re considering switching from aluminum to stainless, you’ll want to reduce the pitch of your propeller by two inches.

Size and Pitch Matters

There will be a limited number of propellers available for your motor and these will be based on size and pitch of the blade. This pitch is measured in inches. The type of your hull and the amount of lift will determine the range of pitches for your particular boat. Your propeller should be geared to what your specific load and use is.

What Do You Use Your Boat For?

Props can be a very personal choice. Two people who own the very same boat and the very same engine could need completely different propellers. Do you take your family and friends and a full load out and run wide open? Do you go out fishing with another guy and some tackle? The more weight, the less pitch. The lower the pitch, the flatter the blades.

Lugging and Engine Damage

If you’re turning too few open throttle RPMs, there can actually be a damaging effect to your motor which can end up damaging valves. The term for this is “lugging”. Although it’s more common with an I/O engine, it can happen with any four-stroke motor.

Many Variables to Consider

Although there are many variables in considering the propeller that is right for your engine and use, there are some very simple guidelines.

  • Choose the material that is right for your motor and your budget.

  • Choose the propeller that allows you to operate at wide open RPMs under your normal load with a full tank of gas.

  • Keep your propeller in good condition and have it reconditioned by a good shop if damaged.

When you need help choosing the right propeller for your engine and your needs, call the experts at PowerHouse Marina. We’d be glad to help you out. Call us today at (305) 892-2628.

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