Docking and Maneuvering Sailboats
With Attention to Props and Rudders
~~ Paul V. Hartman ~~
An inboard engine propeller usually turns clockwise (viewed from astern) and is said to be "right hand", or RHP. In forward gear, with the rudder straight, propeller "crawl" 1 (a weak force) exerted to starboard together with propeller "wash" or "push" (a stronger force) against port causes the stern to move to starboard; in reverse gear the action is the opposite and the stern moves to port. This is "prop walk". The effect is greater in reverse than in forward, and greater in sailboats because of the deeper draft, very large rudder, and other factors. The greater the angle of rudder turn, the greater the presented surface for prop wash, the greater the pressure, the greater the resultant effect.
In Forward gear, Prop Walk is to Starboard. In Reverse gear, Prop Walk is to Port.
Center of Action, or Pivot Point
When moving in Forward, a sailboat's pivot point is about 1/3 the way back from the bow (approximately the location of the mast). If the boat is turned so as to go to starboard, there is more movement of the stern to port then of the bow to starboard. If you are along side a starboard dock and begin to power forward and away from the dock, the bow will move away from the dock slower than the stern will move towards it. Thus, unless you begin by pushing the stern off, motoring forward will cause the stern to collide with the dock.
When moving in Reverse, a sailboat's pivot point is about 1/3 the way forward from the stern (a point just forward of the wheel pedestal). If the boat is put into a turn, the bow will swing much faster than the stern.
In Forward gear, Pivot Point is at the Mast. In Reverse gear, Pivot Point is at the Pedestal.
Wind and Current
Wind acts on the part of the boat above water, and usually influences the larger bow surface more than the stern surface. Water current acts on the part of the boat below the water line. Since sailboats offer a larger underwater surface, sailboats are much more affected by current than are power boats. Nevertheless, for most sailboat docking maneuvers, the wind usually provides the most docking difficulty. At any given time and place, current is usually constant in speed and direction, but you cannot depend on wind to do either.
Skillful docking of a sailboat, with its (typically) small engine, heavy weight, and very large rudder, anticipates - indeed, employs - both prop walk and pivot point.
It is easier to approach a dock on the port side than the starboard. Approach at a 25 degree angle with a fender on the bow, slow the engine, touch the bow gently to the dock, use a little Reverse engine (with rudder straight or turned to starboard), and via prop walk to port, the stern should tuck to the dock.
Approach a starboard dock at a narrower approach angle - 15 degrees rather than 25 - to avoid needing reverse engine and therefore getting prop walk to port. Touch the fendered starboard bow to the dock gently, and with the engine still in Forward with the rudder to port, the stern, because of the pivot point forward (stern moves more than bow) and prop walk to starboard, will tuck to the dock.
Whether the dock is to port or to starboard, the tie-up maneuver is the same: you need a 35-40' dock line attached to a bow cleat passing to the cockpit (on the dock side) outside the life-lines, with a wrap or two on the genny winch to keep it near at hand. You have a second line attached to a stern cleat. As the stern of the boat touches the dock, belay this second line to a dock cleat, step on to the dock with the line from the bow, and adjust it for proper positioning of your boat at the dock. If you haven't got a second line, or haven't the time to retrieve one, then do it all with the line from the bow, first belaying it to the closest dock cleat, then pulling on the forward part of this line to bring the bow to the dock.
It is easier to back away from a starboard side dock since the prop walks the stern to port. This is a good maneuver before moving forward. It is easier to pull forward away from a port dock as prop walk is to starboard but you will still have to push the stern off because, in forward, with the point of rotation at the mast, the stern moves more than the bow.
If required to turn within a narrow space, it is better to circle to starboard (clockwise), since, when alternating with Reverse the stern will move to port even if the rudder is not moved.
Note that a boat will not obey steering effort if it is not moving. It is desirable to make docking maneuvers slowly, but not so slowly that steering is no longer possible. If you loose momentum, regain it by putting your boat in Forward gear.
Approach the slip on the same side of the waterway as your berth is located and, at 20-30 feet from the slip, slow engine to idle and turn away from the slip slowly, allowing the boat to "slide" in front of the slip with the stern ending up at the slip opening. (Practice will make it natural.) Engage reverse, straighten rudder, and as sternway is gained, turn rudder in the direction you wish to go, remembering that even with the rudder straight the stern will move to port. Once within the slip, any use of Forward will kick the bow to port unless resisted with some starboard rudder. Guard against over steering.
When trying to establish the point at which you begin your turn in order to "slide" the transom in front of the slip, err on the side of coming up short (start the turn sooner than you think necessary) rather then over shooting the mark, since you will be able to recover the extra distance needed with a few Forward then Reverse motions with minimal throttle. Once confidence in sterning-in is gained, you will be able to drop the stern dead in the water at the mouth of the slip and pull it in by hand, if that suits you!
Sterning-in has the advantage that you can grab from the cockpit a prepared dock line hanging on a forward piling, and drop the loop onto a stern cleat, thus insuring that your drift aft is limited and your transom will not be damaged. Note this advantage: you are securing prepared dock lines from your position at the wheel as your boat just enters the slip, rather than after it is fully in, as occurs when berthing bow-in.
Do this with precision with a large sailboat, and you will be heralded throughout your harbor!
Other advantages of sterning in: 1) it is the typical docking practice in many European seaside countries; 2) it is common in the Caribbean; 3) since the shore power connector is at the stern, you will need a shorter length of power cord to reach shore power when berthed stern-in.
1 The words "crawl" and "wash" are used here as more intuitive terms to describe what is actually a series of Pressure forces acting against hull, rudder, and water. My apology to the physicists reading this.