docking seamanship 205
One way to minimize rudder use is to make prop walk work for rather than
against you. Prop walk is the tendency of a propeller to “walk” the stern in the direc-
tion of its spin. Th ink of it this way: Th e blades of a right-handed prop travel to the
right at the top of their rotation (in forward gear) and to the left at the bottom of
their rotation. Th e water they encounter at the bottom of their rotation is slightly
denser and less aerated than the water nearer the surface, so the prop blades get
a better “grip” over the bottom half of their swing. Th e result is to direct the prop
wash slightly to port rather than directly astern, and the tendency of that net thrust
to port is to push the stern to starboard.
It doesn’t matter if your boat is moving forward or backing up. If the propel-
ler rotates to the right, the stern moves to the right. If the propeller rotates to
the left (as a right-handed prop will do when the engine is operated in reverse
gear), the stern moves to the left.
Before maneuvering any single-screw vessel, determine its prop rotation
direction in reverse gear. Place the rudder amidships and shift into reverse gear.
If the stern “walks” to the left , you have a right-handed prop. If the stern walks
to the right, you have a left -handed prop. Right-handed props are more common
than left -handed.
Next, understand what happens to the rudder under the water when you turn
the wheel or tiller. When you turn your wheel to the right, the trailing edge of the
rudder blade also turns right, and this turns the bow to the right when the boat is
moving forward. Th e opposite happens when you turn the wheel to the left. Tillers
connect directly to the rudderpost, so when you push a tiller to the left , the trailing
Turning the wheel on a powerboat or sailboat repositions the rudder as shown.