Anchors-Docking

A keelboat is often required to enter a dock or marina under power, with the sails down. However, do not take down the sails until the motor is running. Conversely, when leaving, do not turn off the motor until the sails are hoisted. If anchored outside a designated anchorage, sailboats are required to display a single 360 degree white light on the top of their mast. During the day and outside a designated anchorage, sailboats are required to display a black ball shape.

Docking ( Go To Top ) Larger sailboats are harder to dock than smaller ones. In fact, docking a large boat can be harder than sailing one. Large boats have inertia and they do not stop easily. Your controls are as follows:

Forward (transmission set in forward) with the ability to have the bow move to the starboard, port, and go straight.

Slow forward (transmission set in reverse) with the stern moving towards port (right-handed prop) or starboard (left-handed prop).

Notice, nothing was said about going in reverse. Reverse practically does not exist when docking a large boat. You only slow down and in the process you will experience prop-walk which will swing the stern (back) of your boat in one direction or the other, depending upon the rotation of the propeller.

Prop-Walk: The propeller not only moves water forward and aft (backward) but also to the side. The side motion of the water will swing the boat's stern in one direction or the other depending upon the rotation of the propeller. Prop-Walk is much more pronounced in reverse than forward directions.

In a right-handed prop, the propeller will rotate clockwise when the transmission is in forward and the boat will turn to port more efficiently than starboard. In reverse, the stern will swing to port.

In a left-handed prop, the propeller will rotate counter clockwise when the transmission is in forward and the boat will turn to starboard more efficiently than port. In reverse, the stern will swing to starboard.

How to pick a slip: Always try to find a slip that has a good approach or a wide channel behind it so a tight and accurate turn is NOT required to place the sailboat in the slip. If your boat has a right-handed prop (most do) the ideal slip is one that the docking platform is on the port side of your boat and when leaving the slip you will back out and swing your boat to port to enter the channel behind the slip. If there is a wind blowing (or current flowing) across the beam, you may want a slip which has the docking platform downwind or down current to the side of your boat. This will allow the current or wind to push your boat to the platform, as opposed to the boat in the adjoining slip. (The choice of a leeward or windward docking platform is dependent upon the responsiveness of your boat, the strength of the wind and current, the presence of other boats, and the width of the slip.) It should also be noted, that pulling away from a downwind platform can be difficult. Pulling into a slip with a forward wind is preferable to pulling into a slip with an aft wind. A boat can be controlled with the wind and current pushing the boat backward, with forward throttle and a small amount of reverse; but a boat is difficult to control with the wind and current pushing the boat forward.

If you are going to stay at a marina, ask the harbormaster for a diagram of their docks. Beware, these diagrams are sometimes not to scale and distort distances. However, you can often obtain an aerial photograph of the docking facility online, which will help you judge the ease of docking in individual slips.
Global Explorer -To obtain online aerial photographs of a marina: http://www.globeexplorer.com/

Sailor's Tip: Always remember that in reverse, boats having a right-handed prop (one of the most common types of props) will swing the stern towards port making it easier to dock or go to port on the port side.

A boat is not a car. Remember that when steering a boat you turn the wheel depending on the direction the boat is going NOT the setting of the transmission. There is a lag time between placing the transmission in forward and when the boat actually moves forward. Thus, when backing out of a slip, place the transmission in reverse and move into the channel (1). Turn the wheel or tiller to move your boat into the canal. Before you reach the midline position of the channel, place the transmission in forward (2). The boat will slow. When the boat starts to move forward, turn the wheel or tiller and navigate the channel (3). Do not turn the wheel or tiller until the movement of the boat changes direction. ( Click on Picture to Enlarge !! )

The most important thing to remember are as follows:

Call ahead for help at the dock.

Reserve an oversized slip with a favorable approach and exit.

Go slow, 1 knot. Never gun the engine to try to avoid a collision. A sudden high power throttle in reverse will not slow a large sailboat significantly but will swing the stern of your boat due to prop-walk.

Observe both current and wind direction.

Have a crew member with a fender upfront to soften possible collisions.

Be sure to have fenders on the side of the boat your are going to dock on and the docklines ready (tied to cleats and passed UNDER, not over, the lifelines.)

Know where the king-spoke is. This is the spoke on the ship's wheel that when placed at 12:00, the rudder is straight. Always mark this spoke with tape or place a wooden knob over the spoke, see right figure.

Pulling away from a crowded docking platform can be difficult. The use of spring lines can swing the stern (or bow) away from the dock. One may want to us an aft spring line extending from the bow to the docking platform. The angle of an aft spring line's resistance will help to pull the stern away from the docking platform. Initially, turn the wheel away from the docking platform (tiller towards the docking platform) to hold the boat against the dock. To pull away from the dock, turn the wheel towards the docking platform (tiller away from the docking platform ) and give a small amount of forward power. This will swing the stern of the boat out into the channel. Then put the boat in reverse and leave the docking platform. ( Click on Picture to Enlarge! ) ** GO TO Animated GIF on use of spring lines **

If you approach a docking platform which has a crosswind, you need to approach at a greater angle and with increased speed. Once you place your boat parallel to the docking platform it will be blown away if not secured. A trick to use in this situation is to approach the docking platform at a 60 degree angle. Throw a line from the midship cleat (if you boat does not have a midship cleat use a chain plate) and secure the line to a cleat on the dock. Now turn the wheel away from the docking platform (tiller towards the docking platform ) and give a small amount of forward power. This will swing the boat towards the docking platform, which you can then secure with docklines.
( Click on Picture to Enlarge !! )
** GO TO Animated GIF on docking with a midship spring line **

Anchoring Go To Top

The rode is the line and/or chain which goes to an anchor. It is often composed of both chain and rope. The chain is attached to the anchor and it helps the anchor to lie flat on the bottom. This has three benefits:

	The chain lies flat on the bottom and increases the horizontal pull on the anchor. This will increase the anchor's purchase.
	The chain will not chafe as it lies on and is pulled across the bottom.
	The chain acts as a shock absorber as the boat intermittently pulls on the rode, lifting the chain off the bottom.

One must be sure that the anchor has a good purchase on the water's bottom or it will drag and the boat will drift. You can check the purchase by observing the tension on the rode and any change in position of the boat as the boat is placed in reverse. While at anchor, intermittently check the tension on the rode as the boat's bow raises and lowers with the waves. Also take several compass fixes and/or GPS positions to aid in determining if the boat is drifting and pulling the anchor. A common predisposing factor of a dragging anchor is not letting out enough rode. As a general guide, let out at least seven times the rode as the depth of the water plus the boat's freeboard (distance from the water surface to the deck) This ratio is called the anchoring scope. The scope may be decreased to 5:1 if an all chain rode is used. Scope may have to be increased in high wind or wave conditions. Be sure to check the depth of the water where you anchor in relationship to the tide or you may inadvertently become grounded. If a single anchor is placed, your boat will swing around the anchor as the direction of wind changes. This is especially true on the coast where one encounters land and sea breezes. The water must be deep enough for anchorage along the entire arch of this swing. If less swing is desired, set two anchors at 180 degrees from each other.

You must also check the tide tables to make sure the water will be deep enough at low tide along the entire radius of swing, and that your scope will be sufficient at high tide. For example, if you anchor with a 7:1 scope at low tide in six feet of water and a six foot tide comes in, your scope will be reduced to 3.5:1.

NAOO Tides Online (You can view tide tables and graphs from various locations around the USA): http://tidesonline.nos.noaa.gov/monitor.html

Free Tide Prediction PDA Software for Palm OS : http://www.toolworks.com/bilofsky/tidetool.htm

Go To: Swinging Radius at Anchor Calculator

In a crowded anchorage, always anchor in a similar fashion as the boat next to you or the two boats may drift into each other. For example: If your boat is fixed in place with two anchors and the other boat has a single anchor, the other boat may be blown into your boat. In addition, look at the other boats in the anchorage and take note of the type and the angle of their rodes to the water. This will help you judge the amount of rode let out and give an idea of the swing radius of the other boats. Remember if a boat has an all chain rode, it may have a 5:1 or less scope and have a smaller swinging radius than a boat with a combination chain and rope line. Boats that are anchored next to each other that have a different swing radius are also at greater risk to drift into each other if the current or wind changes. ( Click on Picture to Enlarge !! )

Sailor's Tip: Place fathom or foot markers on the rode to help judge how much line has been let out.

A good anchorage has the following characteristics:

Protected from wind and waves & swells.

Enough depth at low tide along the full swing of the rode.

Enough space along the full swing of the rode.

Good bottom which will hold an anchor.

Types of Anchors:

	Danforth - Holds well in soft surfaces, but may not hold on hard surfaces.
	Bruce - For both hard and soft surfaces
	Plow - A burying anchor for hard surfaces. Notice the ring on the anchor's crown for attachment of a retrieval line (trip line) which is floated up to a buoy.

Sailor's Tip: One may place a second line (trip line) to the head of the anchor. There is usually a metal loop to allow for the placement. Bring the line up to the surface and attach to a flotation device. Using this line the anchor can be pulled out by its head and will be easy to remove. The length of the trip line is equal to the water depth at high tide plus 5 to 10 feet.

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Web page last updated: 12/16/2007

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