How bad will my prop walk be?

Now that you know what propeller walk is, and what makes its effects worse, it is time to figure out how your own boat will respond.

There are generalities, such as Right Hand propellers will walk to port when in reverse and Left Hand propellers will walk to starboard when in reverse. It is easy to know which propeller you have by looking at the hub. Stamped on the hub of the propeller will be LH for Left Hand or RH for Right Hand.

This propeller is Left hand, which means it will walk to starboard when in reverse. Great! This is easy to tell on a boat that is out of the water with a propeller that is high and dry. What if your boat is sitting in the slip with the propeller under water and below the hull? How will you read if your propeller is RH or LH? You don't have to!

Instead of worrying about which handed propeller you have and then trying to remember RH to port under reverse or LH to starboard under reverse, simply observe the way your prop wash moves around your yacht. This will give you a real world understanding of how your vessel will behave. 

All the factors that relate to prop walk will be tied together and prominently displayed for you in one easy test. All you need to do is tie the boat up in a slip on a calm day with still water and put it in reverse under hard throttle. 

As you know, hard throttle will lead to faster propeller speed which will cause prop walk. This along with prop angulation, enclosures, hull and keel type, will compound to display how the entire system will behave in the real world and not just in the theoretical realm.

With the boat properly tied and placed in reverse under hard throttle, look at the water around your yacht and note where the prop wash is coming out. In the most idealistic situation, all the prop wash would rush out from under the bow of the boat. This would indicate that all the thrust from the propeller is being directed forward and the boat will move astern in a straight line with no prop walk.

If you see the prop wash coming up on one side of the hull, then you know you will have prop walk away from the side you see the prop wash rising up on. This is because the thrust is being directed towards one side of the boat, and the boat will move away from the direction of thrust causing it to walk towards the side without the thrust and notable prop wash.

How severe your prop walk will be is directly, related to where the prop wash is appearing in relation to the boat. If the prop wash is appearing near the bow of the boat, the prop walk will not be that severe. If the prop wash is appearing near the stern (or near the propeller) then you know the prop walk will be more severe. Worst case scenario, the thrust and prop wash will appear all on one side of the hull and directly next to the propeller. This would indicate that all the thrust is being projected laterally from the propeller, creating a boat that will reliably move forward and sideways. 

While it would be ideal to have a boat that can comfortably pull in and back out of a slip, knowing how to use your prop walk will help you maneuver your yacht in close quarters without the sheer panic of a boat that is moving the wrong way when you didn't expect it to. Once you know how your boat will respond when placed in reverse, you can properly predict and plan out your approach and exit from a berth without causing an entertaining show for all the bystanders who are waiting to grab a line and pull you into the slip to end your embarrassment.