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

1. Maintain continuous dead reckoning plot.
2. Take two or more star observations at morning twilight for a celestial fix. (prudent to observe 6 stars)
3. Morning sun observation. Can be taken on or near prime vertical for longitude, or at any time for a line of position.
4. Determine compass error by azimuth observation of the sun.
5. Computation of the interval to noon, watch time of local apparent noon, and constants for meridian or ex-meridian sights.
6. Noontime meridian or ex-meridian observation of the sun for noon latitude line. Running fix or cross with Venus line for noon fix.
7. Noontime determination the day's run and day's set and drift.
8. At least one afternoon sun line, in case the stars are not visible at twilight.
9. Determine compass error by azimuth observation of the sun.
10. Take two or more star observations at evening twilight for a celestial fix. (prudent to observe 6 stars)

Passage planning

Main article: Passage planning

Poor passage planning and deviation from the plan can lead to groundings, ship damage and cargo loss.

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,^[19] however on larger vessels, the task will be delegated to the ship's navigator.^[20]

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.^[20] The practice of voyage planning has evolved from penciling lines on nautical charts to a process of risk management.^[20]

Passage planning consists of four stages: appraisal, planning, execution, and monitoring,^[20] which are specified in International Maritime Organization Resolution A.893(21), Guidelines For Voyage Planning,^[21] 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.^[7] 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.^[7] The navigator becomes a system manager, choosing system presets, interpreting system output, and monitoring vessel response.^[