Prop Walk and other Mysteries

“Prop Walk” and Maneuvering Around The Marina

One of the trickiest parts of sailing doesn’t have anything to do with sailing.  It has to do with motoring around the marina.  This includes backing out of a slip, shifting into forward gear after backing out of the slip, and motoring back to the slip.  For new sailboat owners, successfully backing out of a slip may be the trickiest and toughest part to boat ownership.

The reason that backing out of a slip is so tough is because sailboat engines are notoriously underpowered; AND the propellers are also very small compared to the size and weight of the sailboat.  Compare for example a twenty-five foot long powerboat and its fifty to two hundred horse-power engine and huge propeller with a twenty-five foot sailboat with its six to ten horse-power engine with its “tiny” propeller.  The “tiny” propeller doesn’t move much water with each revolution…… BUT, the propeller can “walk” the stern of the boat to the left or to the right before the boat begins moving either forward or backward.

We talk about the propeller being either “left handed” or “right handed”.   This refers to the rotation of the propeller when in forward.  If the boat is not moving and the propeller begins to turn, the rotation causes the propeller to “paddle-wheel” and move the stern of the boat to one side or the other.  A “right hand” propeller tends to walk (prop walk) the stern to the right (starboard) in forward; and to the left (port) in reverse.

 

Problems are created for new sailboat owners if the “prop walk” moves the stern in the “wrong” direction…… to the left when the skipper wants the stern to pivot toward the right.  No amount of rudder angle will prevent the “prop walk” because the boat is not moving forward or backward; so, no water is flowing along the rudder.

 

The problem becomes worse as the stern continues to pivot in the wrong direction.  If the boat eventually makes it out of the slip, the boat is headed in the wrong direction.

The easiest solution to overcome the effects of “prop walk” is to use the tiller on the outboard engine to help turn the transom in the desired direction.  This takes some practice so-as to know how much to turn the engine while in reverse and when to straighten out the engine before engaging forward gear.

Another problem occurs after the boat is out of the slip.  If the skipper has backed out successfully, he/she often thinks (wrongly) that the boat should be lined up straight down the slip row before shifting into forward.  The boat may be stopped in the water or even be backing up.  So, considerable “prop walk” is going to take place as the boat is shifted into forward gear.  If the boat is lined up straight before shifting into forward, the stern pivots to the right and as the boat gains forward direction, the skipper finds that the boat is now aimed at the boats and slips across from the slip just exited.

 

It is better to back the boat out to about a forty-five degree angle and then shift into forward.  The transom pivots with the “prop walk” to the right - - aiming the bow right down the slip row.  Yea!!!!  A perfect backing out and motoring away.