ANDERSON TURN ( MOB )

The Anderson Turn is a maneuver used to bring a ship or boat back to a point it previously passed through, for the purpose of recovering a man overboard, an emergency situation in almost all circumstances.
The Anderson Turn is most appropriate when the point to be reached remains clearly visible. For other situations, a Scharnow turn or a Williamson turn might be better. Both will require more time before returning to the MOB.

If in response to a man overboard, put the rudder toward the person (if the person fell over the starboard side, put the rudder over full to starboard).
When clear of the person, go all ahead full, still using full rudder.
After deviating from the original course by about 240 degrees (about 2/3 of a complete circle), back the engines 2/3 or full.
Stop the engines when the target point is 15 degrees off the bow. Ease the rudder and back the engines as required.
If dealing with a man overboard, always bring the vessel upwind of the person. Stop the vessel in the water with the person well forward of the propellers.

MAN OVERBOARD (SAILING VESSEL

The Quick turn is the main response to the Man overboard emergency on a sailboat. Despite many new approaches, it is still a good strategy and often the best method. When the crew is short handed, or when the vessel is in heavy weather, the Quick turn method is good because it avoids a jibe.
The Quick turn is essentially a figure eight. On a sailboat it consists of the following steps:

Calling out "Crew Overboard"
Assign a person to keep the victim in sight and clearly point towards him or her.
Hit the MOB button on the GPS.
Start the engine and leave it in idle.
Change course to a beam reach and hold for about 15 seconds.
Head into the wind and tack, leave the jib fluttering.
Veer off until the boat is at a beam reach.
Turn up wind until the vessel is pointing at the victim, at this point the vessel should be on a close reach.
Slacken the main sail until the vessel comes to a stop with the victim on the lee side of the boat.
Hoist the victim on board with a sling, the spinnaker halyard can be very helpful if it is available.

AIDS TO NAVIGATION

A navigational aid is a marker that aids the marineer in navigation, the term is most commonly used to refer to nautical travel. Common types of aids include lighthouses, buoys, fog signals, and day beacons.According to the glossary of terms in the United States Coast Guard Light list, an Aid to Navigation is any device external to a vessel specifically intended to assist navigators in determining their position or safe course, or to warn them of dangers or obstructions to navigation.

ATONs can be buoys, daybeacons, and lighted buoys. Daybeacons are on posts or other structures fixed to the bottom, and buoys float in the water. They can be different colors, and may or may not be lit.

Lateral Markers
Red ATONs always have even numbers, and green ATONs have odd numbers. Under the IALA B standard used in North and South America, when you are going to sea, the red ATON is on your left, and the green on your right. Under the IALA A standard used in Europe, Africa and most of Asia, the colors are reversed.
In the IALA B system, the red ATONs are on your right when you return from sea (Red Right Returning) and the green on your left. Red daybeacons are triangles and green daybeacons are squares. All of these ATONs are Lateral Markers that mark traffic channels and where it is safe to travel.

Non-Lateral Markers
There are also Non-Lateral Markers that give information other than the edges of safe waters. Most are white with orange markings and black lettering. They are used to give direction and information, warn of hazards and destructions, mark controlled areas, and mark off-limits areas. These ATONs do not mark traffic channels.
On Non-Lateral Markers, there are some shapes that show certain things:
Squares - show information, including places to find food, supplies, and repairs. They sometimes show directions.
Diamonds - warn about dangers like rocks, construction, dams, or stumps.
Circles - mark a controlled area such as no wake, idles speed, speed limit, or ski zone.
Crossed diamonds - show areas off limits to all boats, like swimming areas and dams.

Junction Buoys
There are some special colored ATONs. When there are red and green horizantal stripes, you are at the junction of two channels. The ATONs indicate the primary channel. If the green is on the top, the preferred channel is to the right. If the red is on top, the preferred channel is to the left. The light matches the top stripe color. These ATONs are sometimes called "junction buoys."

CHIP LOG

A chip log consists of a wooden board attached to a line (the log-line). The log-line has a number of knots tied in it at uniform spacings. The log-line is wound on a reel to allow it to be paid out easily in use.
The shape is a quarter circle, or quadrant and the log-line is attached to the board with a bridle of three lines connected to the vertex and to the two ends of the quadrant's arc. In order that the log submerges and is oriented correctly, the bottom of the log is weighted with lead. This provides for more resistance in the water and a more accurate and repeatable reading of speed. The bridle is attached in such a way that a strong tug on the log-line results in one or two of the bridle's lines releasing, allowing the log to be retrieved with relative ease.

Usage
When the navigator wanted to know the speed of his vessel, a sailor dropped the log over the stern of the ship. The log would act as a drogue and remain roughly in place while the vessel moved away. The log-line was allowed to run out for a fixed period of time. The speed of the ship was indicated by the length of log-line passing over the stern during that time.

Origins
The first known device to measure speed is claimed to be the Dutchman's Log. An object that would float was thrown overboard and the time required to pass between two points on deck was measured with a sandglass.
The log has been used by mariners for a long time. Initially, the log-line was not knotted and the length was measured directly on the line. With the introduction of the nautical mile as a standard unit of measure at sea, the line began to be marked at equal intervals proportional to the nautical mile and to the time interval used for measurement. The markings were in the form of knots in the line. Later, knotted cords were worked into the log-line.
Originally, the distance between marks was 7 fathoms or 42 feet used with a sandglass with a 30 second running time. Later refinements in the length of the nautical mile caused the distance between knots to be changed. Eventually, the distance was set to 47 feet, 3 inches (14.4 meters) for a standard glass of 28 seconds.
The name of the unit knot, for nautical mile per hour, was derived from this method of measurement.

DEAD RECKONING (DR)

Dead reckoning (DR) is the process of estimating one's current position based upon a previously determined position, or fix, and advancing that position based upon known speed, time, and course. While traditional methods of dead reckoning are no longer considered primary in most applications, modern inertial navigation systems, which also depend upon dead reckoning, are used more today.

In marine navigation a DR plot generally does not take in to account the effect of currents or wind. Aboard ship a DR plot is considered important in evaluating position information and planning the movement of the vessel. Dead reckoning (DR) begins with a known position, or fix. This fix is then advanced, mathematically or directly on the chart, by means of recorded heading, speed, and time. Speed can be determined by many methods. Before modern instrumentation, it was determined aboard ship using a chip log. Distance is determined by multiplying the speed and the time. This initial position can then be adjusted resulting in an estimated position (EP) by taking into account the current (known as set and drift in marine navigation). If there is no positional information available, a new DR plot may start from an estimated position. In this case subsequent DR positions will have taken into account estimated set and drift.

DR positions are calculated at predetermined intervals, and are maintained between fixes. The duration of the interval varies. Factors including one's speed made good and the nature of heading and other course changes, and the navigator's judgment determine when DR positions are calculated.
Before the development of the marine chronometer, dead reckoning was the primary method of determining longitude available to mariners such as Christopher Columbus and John Cabot on their trans-Atlantic voyages.

TIDAL CURRENTS

Tidal Currents
There are several different kinds of currents including oceanic, river, and wind-driven all with their own driving force.
Tidal currents (a horizontal motion) are a result of the rise and fall of the water level due to tides (a vertical motion). The effects of tidal currents on the movement of water in and out of bays and harbors can be substantial.

Terminology
Set
The set of a current is the direction that it flows toward. Note that this is the opposite of the way winds are reported.
Drift
This is the speed of a current, on ocean waters it is usuallly stated in knots, in rivers, mph.
Velocity
This is an indication of both speed and direction (set and drift).
Speed
How fast the water is moving in relation to a stationary object.
Flood Flow
The tidal current is in flood when it is coming from the sea to the shore (tide is coming in, or high tide is.
Ebb Flow
The tidal current is in ebb when it is coming from shore and returning to the sea.
Slack Water
The point between flood and ebb (or ebb and flood) currents when there is no horizontal movement.
Stand
The point where vertical changes stop as the tide reverses. This is not the same as slack water, this is a tidal (vertical), not a tidal current (horizontal).
Maximum Current
The normal maximum speeds of the ebb and flood currents. This does not include effects of weather or run off from rain or melting snow, which can effect tidal currents.

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