Most
boat owners are familiar with the use of spring lines to keep their boat alongside the
dock without moving, and how springs can
permit other boats to raft up to you without surging back and forth.
The spring line is also a simple solution to many
docking and undocking situations.
Springing Off involves removing all your lines except one spring line, then motoring against it so that the opposite end of the boat is levered off the wall.
~ With the
Wind Ahead: Reverse the
engine with the
rudder hard to port and the bow will spring out away from the pier. Use a
fender at the stern for protection, and be careful if you have a swim platform or
davits extending
outboard.
~ With the
Wind Abeam (Pushing you onto the dock): An aft bow spring is run, and the
engine is put in forward with the
rudder hard to port. A
fender should be used for protection as the bow comes into the pier. The stern will swing out until you can safely retrieve the spring and reverse neatly away from the pier. The same method can be used if you find yourself tightly surrounded by boats since it doesn't require more dock space than you already have.
~ To spring your stern off:
Motor slowly ahead against a bow spring, using the rudder to deflect the propwash.
~ To spring your bow off:
Motor astern against the stern spring. The position of the rudder is irrelevant
(*see "Wheels" later comments), but remember that as you motor away you will be pivoting; don't grind your quarter into the dock.
Don't forget to use your fenders intelligently while springing off, and always be sure that you can let go the spring line without leaving one of your crew on the dock. Run all spring lines back to the boat.
If you have the more common 'right-handed'
propeller, you will find that when the engine is put astern, the stern of the yacht will “prop walk” to port, and vice versa with a left-handed prop. On some craft this can be so positive that it becomes a primary maneuvering tool; in others it is barely perceptible. What you need to determine by
experiment is which way the stern will go and how hard. Use this information when
docking - come alongside, such that your prop walk will assist you in getting off. If there is no tide and not much breeze, you should always choose to put the side to the dock OPPOSITE to which the boat naturally favours.
Most authorities suggest you use prop’ walk to assist in approaching a dock.
I always consider how I’m going to get off the dock, and tie up so as to ease the undocking maneuver.
Here's an aggressive approach to turning a boat in tight quarters:
Using rudder direction change and thrust to rotate. Put the
helm hard over in the opposite direction of stern torque (on most boats this means turning the
helm to starboard to continue the turn of the stern torque as it lifts the stern to port), give a strong pulse of
power in reverse, then switch to a comparable pulse forward. Repeat as needed until the perquisite angle is obtained.
We start with the helm hard over to starboard (right hand prop’), with a thrust in forward. This shoves the stern to port. The helm is then quickly switched to port and a shot in reverse is given. The stern torque, plus some rudder action jumps the stern to port, continuing the turn. The process is repeated, forward and reverse, until the correct angle of turn is achieved. Note: turning the helm back and forth only works with boats which have fast acting rudder ratios, and in relatively calm winds (so drift to leeward is not a problem). The boat completes a 180 degree turn (clockwise, to starboard) in less than 2 boatlengths.
Cautions:
1. Keep
power on in each direction only as long as lateral
displacement is taking place. When the turning action becomes forward or aft motion, change the direction of
propeller thrust (usually this is about two to three seconds tops).
2. Allow a second or two for the rpms on the
diesel to drop back to idle before shifting. This is especially critical with Max props, which otherwise slam their blades back and forth putting a lot of stress on the
transmission and engine pressure plate.
3. The above not withstanding, the faster the shifting takes place, the tighter will be the turning circle.
4. Do not try to fight the wind. If your bow is downwind, and there is more than four to six knots of breeze, it may be very difficult to get the boat to rotate against the wind. If you are heading upwind, set the bow off at an angle to the breeze so that it helps blow it to leeward while the prop is pulling to windward.
5. The higher the
rpm (and the more horsepower going into the water) the more rotational energy there will be. However, it is best to finesse this maneuver with minimum necessary bursts of engine rather than using brute force (which is hard on the drive train).
Some on-line tutorials:
Sailboat Docking, Maneuvering and
Anchoring - by
Captain Jack Klang
http://www.quantumsails.com/pdf/maneuvering.pdf
Docking Defense - by Steve Colgate
http://www.boats.com/content/default...ontentid=17609
Spring Lines: The Key to Painless Docking - BoatUS “Seaworthy”
http://www.boatus.com/seaworthy/swlines.asp
HTH,
Gord