Navigation Totally Explained

Everything about Navigation totally explained

Navigation is the process of planning, reading, and controlling the movement of a craft or vehicle from one place to another. The word navigate is derived from the Latin roots navis meaning "ship" and agere meaning "to move" or "to direct." Latitude is usually expressed in degrees (marked with °) ranging from 0° at the Equator to 90° at the North and South poles. A line of position can refer to two different things: a line on a chart and a line between the observer and an object in real life. A bearing is a measure of the direction to an object.
Lines (or circles) of position can be derived from a variety of sources:

celestial observation (a short segment of the circle of equal altitude, but generally represented as a line),
terrestrial range (natural or man made) when two charted points are observed to be in line with each other,
compass bearing to a charted object,
radar range to a charted object,
on certain coastlines, a depth sounding from echo sounder or hand lead line.

There are some methods seldom used today such as "dipping a light" to calculate the geographic range from observer to lighthouse
   Methods of navigation have changed through history. Each new method has enhanced the mariner’s ability to complete his voyage. It is also used to predict a future position by projecting course and speed from a known present position. More so than in other phases of navigation, proper preparation and attention to detail are important. A chronometer differs from a spring-driven watch principally in that it contains a variable lever device to maintain even pressure on the mainspring, and a special balance designed to compensate for temperature variations. A fix consisting of only radar information is called a radar fix.
   Types of radar fixes include "range and bearing to a single object," "two or more bearings," This technique involves creating a line on the screen that's parallel to the ship's course, but offset to the left or right by some distance.
   Another special technique, known as the Franklin Continuous Radar Plot Technique, involves drawing the path a radar object should follow on the radar display if the ship stays on its planned course. During the transit, the navigator can check that the ship is on track by checking that the pip lies on the drawn line. including the replacement of aging satellites, and research and development. Despite this fact, GPS is free for civilian use as a public good.

Navigation processes

Day's work in navigation

The Day's work in navigation is a minimal set of tasks consistent with prudent navigation. The definition will vary on military and civilian vessels, and from ship to ship, but takes a form resembling:

Maintain continuous dead reckoning plot.

Take two or more star observations at morning twilight for a celestial fix. (prudent to observe 6 stars)

Morning sun observation. Can be taken on or near prime vertical for longitude, or at any time for a line of position.

Determine compass error by azimuth observation of the sun.

Computation of the interval to noon, watch time of local apparent noon, and constants for meridian or ex-meridian sights.

Noontime meridian or ex-meridian observation of the sun for noon latitude line. Running fix or cross with Venus line for noon fix.

Noontime determination the day's run and day's set and drift.

At least one afternoon sun line, in case the stars are not visible at twilight.

Determine compass error by azimuth observation of the sun.

Take two or more star observations at evening twilight for a celestial fix. (prudent to observe 6 stars)

Passage planning

Passage planning or voyage planning is a procedure to develop a complete description of vessel's voyage from start to finish. The plan includes leaving the dock and harbor area, the enroute portion of a voyage, approaching the destination, and mooring. According to international law, a vessel's captain is legally responsible for passage planning, however on larger vessels, the task will be delegated to the ship's navigator.
Studies show that human error is a factor in 80 percent of navigational accidents and that in many cases the human making the error had access to information that could have prevented the accident. and these guidelines are reflected in the local laws of IMO signatory countries (for example, Title 33 of the U.S. Code of Federal Regulations), and a number of professional books and publications. There are some fifty elements of a comprehensive passage plan depending on the size and type of vessel.
The appraisal stage deals with the collection of information relevant to the proposed voyage as well as ascertaining risks and assessing the key features of the voyage. In the next stage, the written plan is created. The third stage is the execution of the finalised voyage plan, taking into account any special circumstances which may arise such as changes in the weather, which may require the plan to be reviewed or altered. The final stage of passage planning consists of monitoring the vessel's progress in relation to the plan and responding to deviations and unforeseen circumstances.

Integrated bridge systems

Electronic integrated bridge concepts are driving future navigation system planning. Integrated systems take inputs from various ship sensors, electronically display positioning information, and provide control signals required to maintain a vessel on a preset course. The navigator becomes a system manager, choosing system presets, interpreting system output, and monitoring vessel response.Further Information

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