Prop Walk

Almost everyone has heard of prop walk and quite a few of us will have had boats which exhibit this characteristic.

For those that don’t know, prop walk occurs when initially engaging reverse gear and applying power to stop the vessel or get it moving backwards. The stern of the vessel “walks” to port if you have a right handed propeller until the vessel has some way on and can be steered with the rudder. In the comparatively rare case of a left handed prop the stern will “walk” to starboard.

In actual fact boats pivot round a point about one third of the boats length from the bow. So while the stern is going one way the bow is going the other way.

The effect is limited to single screw vessels where the prop shaft is angled downwards, plus the underwater shape of the hull can increase the effect. Boats with flat bottoms and propshafts that are horizontal, which includes sail drives, don’t suffer from prop walk. That eliminates most power boats and yachts of modern design. However there are still a lot of good, older boats out there with this problem.

Whilst it might be nice to not have a boat with prop walk it does have some advantages. As long as you can plan to come along side a berth port side to, the prop walk will pull your stern in to the pontoon for you.

It also makes it easier to turn a single screw boat around in a limited space. By turning to starboard and applying a burst of power astern, the prop walk will pull the stern to port. Before the boat gets any stern way on a quick burst of power ahead will keep the boat turning to starboard. Keep the rudder hard to starboard the whole time. There is no point moving it as the boat should not get too much stern way and therefore doesn’t need steering backwards. Also don’t let the boat get moving forward. Apply just a short burst of power so that the wash from the propeller pushes against the rudder, spinning the boat around its pivot point. Always pause briefly between forward and reverse so you don’t damage your gear box.

Anyone who has tried to turn a boat around against the prop walk will know it is near impossible. Also having neatly tucked yourself in a berth using the prop walk it works against you when trying to leave. One way to overcome this is to use a forward spring to move the stern away from the pontoon.

Backing into a berth also presents a problem. If you line up nicely and start backing into the berth by the time you have steerage way you are way off course. To overcome this get the boat at an angle to the direction you want to end up heading in taking into account the prop walk. Hopefully by the time you have steerage way you will be lined up with your berth.

All boats are different and some will have a more pronounced prop walk than others. As ever, practicing manoeuvres in open water on a calm day helps in learning how much you need to allow for any prop walk and will give confidence when doing close quarters manoeuvring.