how to reduce prop slip

How To Reduce Prop Slip? [Here’s How To Do It]


About to start a fun day on your boat but then noticed that your prop slip is extended? That could ruin your whole mood. But you can easily reduce it and give a headstart to your eventful day. 

So, how to reduce the prop slip?

First of all, you’ll need a correct setback. Then you have to trim the prop. After that, you should be checking if you’ve spun the hub or the coupler. Finally, you need to fix the slippage along with the diameter.

This was just the tip of the iceberg. There’s more in detail you must know before fixing this. We have got the entire guide in steps four you. 

Sounds like what you’re looking for? Let’s get into it right away!

How To Calculate The Prop Slip?

If you don’t want your prop slip to extend every now and then, do the right calculations. You can easily calculate the prop slip while lubing the steering cable on the boat. You can also calculate it any other time.

A propeller for a boat has two fundamental dimensions. The first is diameter, and the second is pitch. These are normally expressed in inches and are always written as diameter x pitch. 

A 14.5 x 19 propeller, for example, has a diameter of 14.5 inches and a pitch of 19 inches. Simply calculate the diameter of the prop with a measuring tape to determine its diameter. 

Not sure what type of measuring tape would be the best for this? Well, have a look at our recommendations below-

Product 1
Product 2

These are the products that are efficient. Because you can use these for various purposes!

On the other hand, propeller pitch is the distance the prop would go forward in one rotation. It’s like turning a screw into wood. The threads of a screw are equivalent to the blades on a propeller.

What Happens If The Prop Slip Is Extended?

If the prop slip is extended, the engine may run below its WOT range. This is known as lugging. This might put unnecessary strain on the engine and gearcase components. 

So, moving the pitch up or down two inches will usually modify the WOT engine speed. It would also change the RPM by about 400. And if you fail to do it, the outboard motor might not get started.

How To Reduce The Prop Slip?

Reducing the prop slip might sound quite simple. But it isn’t that easy in other words. Because you need to go accordingly when you do it. So, the steps to reduce the prop slip are given below-

Step 1: Trim The Prop

First of all, you’ll need a correct setback, as well as some balance. Then trim the prop if it is not delivering all of its force in a forward direction. At the very least, you’ll lose the vector, as well as the ability to drive the stern down. 

Step 2: Check The Speed Readings

Check to see if you’ve spun the hub or the coupler. They normally all burn up at the same time. Make sure the water flow to the prop isn’t obstructed. Then double-check your tach and speed readings. 

Don’t get confused with the speed readings as some people confuse it with the speedometer. Some people also confuse it with the Cmap or Navionics

Step 3: The Finishing

The tach will display falsely high rpm numbers in this case. In addition, the boat’s horsepower will be reduced, resulting in a slower top speed. Different pitches won’t have much of an impact on slippage. 

More blades or a larger diameter can help, especially if the X dimension is larger. However, your slippage should be less than 15%. So, at 40%, you’re considerably off the mark. And there’s more to it than a 1″ pitch or a 1/2″ diameter difference.

So, you need to make the calculations first. Then you need to follow the instructions as per given above to reduce the prop slip.


Question: What is the average prop slip?

Answer: The majority of setups have a 5-20% slip rate. And, of course, each boat is unique. However, you may notice that the percentage displayed is more than 20. In that situation, switching to a different propeller, altering the drive height, and so on can usually help.

Question: Why does the prop slip?

Answer: Prop slip is caused by a variety of circumstances. This covers the propeller’s actual pitch as well as its current state. It also includes the hull’s design as well as the condition of the craft’s bottom. Additional weight on the vessel, as well as weight distribution, are also incorporated. Finally, the engine height, engine trim angle, setback, and jack plate are all included.

Question: How to identify the bad boat prop?

Answer: First and foremost, there would be too much pitch. On the other side, it could be that it lacks pitch. When you wish to travel quicker, you’ll run out of gas. The amount of fuel consumed would be higher than usual. There are also some other signs and symptoms. Keep one thing in mind. The symptoms may differ slightly from boat to boat.

Question: Is a prop slip considered good for the boat?

Answer: It sounds like an awful situation. When it occurs in the correct percentage, though, it’s actually a beneficial thing. Prop slip is the discrepancy between real and theoretical forward travel in basic terms. It’s caused by the angle of attack of a propeller. Too much prop slip results in poor performance and poor fuel economy.

Question: Is it better to have a 3 prop blade or 4 prop blade?

Answer: A three-blade propeller is typically used for high-speed applications. A four-blade propeller, on the other hand, delivers maximum thrust and smooth cruising. Four blades, on the other hand, have their unique set of characteristics. At the stern, they frequently give additional lift. As a result, the hull will accelerate.

The Final Words

Now you know how to reduce the prop slip! We hope our information was quite helpful for you to put into the implementation. 

We wish you the best with your sailing tasks. Good luck!

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