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FOR FAST ANSWERS TO SOME OF YOUR YAMAHA QUESTIONS.

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From dealership and warranty information to picking a prop and finding a part number, we have answers to many of the questions you may have, right here. If you don’t find your Q & A here, contact the nearest Yamaha marine dealer or call Yamaha Customer Service at (866) 894-1626.

Use the dropdown menu to select your topic of interest. All related questions will be listed below. 

Propellers

How do I find my Yamaha propeller’s pitch and diameter?

Numbers are stamped into each propeller’s inner hub that identify the diameter and pitch size. The first number is the diameter, which may include a fraction. The second number with a propeller series letter identifier beside it will represent the pitch. For example, you may see 15 1/8 X 25T or 13 3/4 X 17M. Some propellers show this information in multiple locations. In the below diagram examples 1, 3 and 5 show you where you may find this on the propeller. Match propellers to outboards

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How should I maintain and service my propeller?

Essential to good propeller maintenance is periodic inspections to detect even small dings, which can lead to loss of performance and even blade failure if not addressed and repaired. A damaged propeller can significantly reduce performance efficiency and fuel economy, and cause imbalance vibrations that can lead to fatigue damage to other parts of the engine or drive. Visually inspect your propeller often, and repair or replace it as needed.

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Should I use a three blade or four blade propeller?

Three bladed propellers are the most widely used, as they provide a good balance of performance characteristics and cost. They are available in a wide variety of styles that make them suitable for most boating applications. From their balanced performance characteristics to their stability and overall efficiency, this style of propeller is the norm. Four bladed propellers offer some specific advantages over their three bladed counterparts, but are not correct for every application. Four bladed props are used where one or more of these advantages are desired to achieve a particular performance goal in a particular boating application. Advantages typically include faster hole shot and acceleration, improved bow lift and the ability to maintain plane at lower slower engine speeds. Improved grip typically allows higher engine mounting heights and trim angles, improved anti-ventilation characteristics in heavy seas, and can also enhance transom lift for heavy transom boats. Four bladed props usually result in lower top speeds; their use can create different boat handling characteristics. They generally need one pitch lower than the proper three blade to maintain the recommended wide open throttle (WOT) engine RPM.

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What are the basic propeller terms and their definitions?

           

 

 

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What do I need to know when selecting a propeller, and how can Yamaha help?

Choosing the right propeller is very important. Propeller blades can be compared to automotive tires. There are different designs, sizes, and shapes to most effectively meet specific performance requirements. Likewise; from the number, size, and shape of its blades to a host of other variable criteria, no one type or style of propeller is perfect for all boating applications. The link below provides some important information needed in selecting the correct propeller for various boat/motor packages. Yamaha publishes Performance Bulletins for over 2000 boat and engine combinations. Visit the Performance Bulletins section for more in-depth information on engine, boat, and prop performance. Look for one that is the same or close to your particular application, then contact an authorized Yamaha Marine dealer.

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What is the difference between cavitation and ventilation in terms of propellers?

Ventilation is the most common, and is when air is drawn in around the propeller blades. Normally, this causes a gain in RPM, but a loss of speed, since the propeller blades are not biting “clean” water. Controlled ventilation can be beneficial, though, in helping the engine gain RPM during hard acceleration. Cavitation occurs when pressure on the water across the blade’s surface is reduced to the point of becoming water vapor, forming bubbles. If these bubbles burst, they can cause a “cavitation burn” which can deteriorate the propeller’s surface and cause negative performance issues. As this condition can cause an increase in engine RPM, it’s often confused with ventilation.

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When looking at my Yamaha propeller, I noticed two numbers and a letter stamped into the side. What do they mean?

The numbers represent the pitch size. The letter is a code that represents the propeller series. The letter code identifies to your dealer what range of outboard motors the propeller is designed to fit. For example- a 17M is a 17" pitch M series designed for outboard motors from 150~300 HP. Below is a diagram showing where you may find this information; locations can differ from prop to prop. Propeller codes

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Why does my boat seem to lose top speed on hot humid days?

On hot humid summer days the air is less dense which causes the engine to run richer and be slightly down on power. To the contrary on cold winter days the air is more dense which causes the engine to run leaner and have more power. If you are concerned with making sure you get the peak performance out of your motor year round it may be necessary to use two different propellers depending on the time of year. To compensate for the loss in power on hot humid days you would need to go down in pitch and on cold days up in pitch. For example you may be running a 26" pitch propeller in the summer and a 27" pitch propeller in the winter.
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