The American Practical Navigator/Chapter 25

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The American Practical Navigator
by the United States government
Chapter 25
Chapters:

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, Glossary, Acronyms

CHAPTER 25:NAVIGATION PROCESSES[edit]

INTRODUCTION[edit]

2500. Understanding the Process of Navigation[edit]

Navigation is comprised of a number of different processes. Some are done in a set order, some randomly, some almost constantly, others only infrequently. It is in choosing using these processes that an individual navigator’s experience and judgment are most crucial. Compounding this subject’s difficulty is the fact that there are no set rules regarding the optimum employment of navigational systems and techniques. Optimum use of navigational systems varies as a function of the type of vessel, the quality of the navigational equipment on board, and the experience and skill of the navigator and all the members of his team.

For the watch officer, ensuring the ship’s safety always takes priority over completing operational commitments and carrying out the ship’s routine. Navigation is his primary responsibility. Any ambiguity about the position of the vessel which constitutes a danger must be resolved immediately. The best policy is to prevent ambiguity by using all the tools available and continually checking different sources of position information to see that they agree. This includes the routine use of several different navigational techniques, both as operational checks and to maintain skills which might be needed in an emergency. Any single navigational system constitutes a single point of failure, which must be backed up with another source to ensure the safety of the vessel.

It is also the navigator’s responsibility to ensure that he and all members of his team are properly trained and ready in all respects for their duties, and that he is familiar with the operation of all gear and systems for which he is responsible. He must also ensure that all digital and/or hardcopy charts and publications are updated with information from the Notice to Mariners, and that all essential navigational gear is in operating condition.

Navigating a vessel is a dynamic process. Schedules, missions, and weather often change. Planning a voyage is a process that begins well before the ship gets underway. Executing that plan does not end until the ship ties up at the pier at its final destination. While it is possible to over plan a voyage, it is a more serious error to under plan it. Carefully planning a route, preparing required charts and publications, and using various methods to monitor the ship’s position as the trip proceeds are fundamental to safe navigation and are the marks of a professional navigator.

This chapter will examine navigational processes, the means by which a navigator manages all of the resources at his command to ensure a safe and efficient voyage.

BRIDGE RESOURCE MANAGEMENT[edit]

2501. The Navigator as Manager[edit]

The development of computers, and navigational technologies driven by them, has led to an evolution some might say revolution in the role of the navigator. Increasingly, the navigator is the manager of a combination of systems of varying complexity, which are used to direct the course of the ship and ensure its safety. The navigator is thus becoming less concerned with the direct control of the ship and more concerned with managing the systems and people which do so under his direction. The navigator must become competent and comfortable with the management of advanced technology and human resources, especially in stressful situations.

A modern ship's navigational suite might include an integrated bridge system with a comprehensive ship and voyage management software package, an ECDIS replacing paper charts and including radar overlay, dual interswitched X- and S-band ARPA radars, autopilot linked to digital flux gate and ring laser gyrocompasses linked to the ECDIS, integrated GPS/DGPS and Loran C positioning system, numerous environmental sensors, digital depth sounder, and Doppler speed log. The communications suite might include a GMDSS workstation with NAVTEX receiver, a weatherfax and computer weather routing system, SATCOM terminal, several installed and portable VHF radios, an internal telephone exchange, a public address and alarm system, and sound powered telephones. As all this technology is coming aboard, crew size is decreasing, placing increased responsibility on each member of the team.

Thus, the modern navigator is becoming a manager of resources, both electronic and human. Of course, he has always been so, but today’s systems are far more complex, and the consequences of a navigational error far more serious, than ever before. The prudent navigator will therefore be familiar with the techniques of Bridge Resource Management (BRM), by which he can supervise the numerous complex tasks involved with maintaining navigational control of his vessel.

Bridge Team Management refers to the management of the human resources available to the navigator helmsman, lookout, engine room watch, etc. and how to ensure that all members contribute to the goal of a safe and efficient voyage.

Bridge Resource Management (BRM) is the study of the resources available to the navigator and the exploitation of them in order to conduct safe and efficient voyages. The terms “bridge resource management” and “bridge team management” are not precisely defined. For most, bridge resources consist of the complete suite of assets available to the navigator including electronic and human, while bridge team management refers only to human assets, except for the pilot, who is normally not considered a member of the team.

The resources available will vary according to the size of the ship, its mission, its crew, its shoreside management, funding, and numerous other variables. No two vessels are alike in resources, for even if two ships of a single class are alike in every physical respect, the people who man them will be different, and people are the most important resource the navigator has.

Effective Bridge Resource Management requires:

  • Clearly defined navigational goals
  • Defined procedures—a system—for achieving goals
  • Means to achieve the goals
  • Measures of progress toward goals
  • Constant awareness of the situation tactically, operationally, and strategically
  • Clearly defined accountability and responsibility
  • Open communication throughout the system
  • External support

2502. Watch Conditions[edit]

Whenever the navigational situation demands more resources than are immediately available to the navigator, a dangerous condition exists. This can be dealt with in two ways. First, the navigator can call up additional resources, such as by adding a bow lookout or an additional watch officer. Second, he can lower the navigational demands to the point where his available resources are able to cope, perhaps by reducing speed, changing course, heaving to, or anchoring.

Some conditions that increase the demands on the navigator include:

  • Fog
  • Heavy traffic
  • Entering a channel, harbor or restricted area
  • Heavy weather
  • Fire, flooding, or other emergency

These and many other situations can increase the demands on the time and energy of the navigator, and cause him to need additional resources another watch officer, a bow lookout, a more experienced helmsman to take some of the workload and rebalance the amount of work to be done with the people available to do it.

There is no strict legal direction as to the assignment of personnel on watch. Various rules and regulations establish certain factors which must be addressed, but the responsibility for using the available people to meet them rests with the watch officer. Laws and admiralty cases have established certain requirements relating to the position and duties of the lookout, safe speed under certain conditions, mode of steering, and the use of radar. The maritime industry has established certain standards known as Watch Conditions to help define the personnel and procedures to be used under various situations.

Watch Condition I indicates unrestricted maneuverability, weather clear, little or no traffic, and all systems operating normally. In this condition, depending on the size and type of vessel and its mission, often a single licensed person can handle the bridge watch.

Watch Condition II applies to situations where visibility is somewhat restricted, and maneuverability is constrained by hydrography and other traffic. This condition may require additional navigational resources, such as a lookout, helmsman, or another licensed watch officer.

Watch Condition III reflects a condition where navigation is seriously constrained by poor visibility, close quarters (as in bays, sounds, or approach channels), and heavy traffic.

Watch Condition IV is the most serious, occurring when visibility is poor, maneuvering is tightly constrained (as in channels and inner harbors), and traffic is heavy.

Any watch condition can change almost momentarily due to planned or unforeseen events. Emergency drills or actual emergencies on one’s own or other nearby vessels can quickly overwhelm the unprepared bridge team.

Under each of these conditions, the navigator must manage his resources effectively and efficiently, calling in extra help when necessary, assigning personnel as needed to jobs for which they are qualified and ready to perform. He must consider the peculiarities of his ship and its people, including considerations of vessel design and handling characteristics, personalities and qualifications of individuals, and the needs of the situation.

2503. Laws Relating to Bridge Resources[edit]

Numerous laws and regulations relate to the navigation of ships, particularly in less than ideal conditions. Title 33 of the Code of Federal Regulations (CFR) specifies bridge visibility parameters. Title 46 CFR and IMO standards relate to medical fitness. Public Law 101-380 specifies the maximum hours of work permitted, while 46 CFR specifies the minimum hours of rest required. Competency and certification are addressed by 46 CFR and STCW 95. Charts, publications, and navigational equipment are the subject of 33 CFR, which also specifies tests required before getting underway. This code also requires reporting of certain dangerous conditions aboard the vessel.

Various U.S. state and local regulations also apply to the duties and responsibilities of the bridge team, and numerous regulations and admiralty case law relate indirectly to bridge resource management.

2504. Pilots[edit]

One of the navigator’s key resources in the harbor and harbor approaches is the pilot, a professional shiphandler with encyclopedic knowledge of a local port and harbor area. His presence is very often required by local regulation or law. He is not considered, by the common definition, to be a member of the bridge team, but he is an extremely important bridge resource. He remains, except in certain defined areas, an advisor to the captain, who retains full responsibility for the safety of the ship. Only in the Suez Canal and Panama Canal are pilots given full navigational responsibility.

As an important navigational resource, the pilot requires management, and as a professional navigator, he deserves respect. The balance of these two elements is the responsibility of the captain, who manages the Master-Pilot Exchange (MPX).

The explicit purpose of the MPX is to tell the pilot the particulars of the ship: its draft, condition of engines and navigational equipment, and special conditions or characteristics which might affect the pilot’s ability to understand how the ship will handle in close quarters. However, simply relating the ship’s characteristics and condition does not constitute a proper MPX, which must be more comprehensive.

The implicit purpose of the MPX is to establish a rapport with the pilot so that a mental model of the transit can be agreed on and shared with the bridge team. Thus, the MPX is not an event but a process, which will ensure that everyone responsible for navigating the vessel shares the same plan for the transit.

Some ships prepare a pilot card that lists the essential vessel parameters for the pilot’s ready reference. The pilot himself may use a checklist to ensure that all required areas of concern are covered. The pilot may or may not require a signature on his own forms, and may or may not be requested or allowed to sign ship’s forms. These are matters of local law and custom that must be respected.

Often, among the pilot’s first words upon boarding will be a perfunctory recommendation to the captain to take up a certain course and speed. The captain then gives the appropriate orders to the bridge team. As the vessel gathers way, the rest of the MPX can proceed. As time permits, the pilot can be engaged in conversation about the events and hazards to be expected during the transit, such as turning points, shoal areas, weather and tides, other ship traffic, tugs and berthing arrangements, status of ground tackle, and other matters of concern. This information should be shared with the bridge team. At any time during the transit, the captain should bring up matters of concern to the pilot for discussion. Communication is the vital link between pilot and master that ensures a safe transit.

2505. Managing the Bridge Team[edit]

Shipboard personnel organization is among the most hierarchical to be found. Orders are given and expected to be obeyed down the chain of command without hesitation or question, especially in military vessels. While this operational style defines responsibilities clearly, it does not take advantage of the entire knowledge base held by the bridge team, which increasingly consists of a number of highly trained people with a variety of skills, abilities, and perceptions.

While the captain may have the explicit right to issue orders without discussion or consultation (and in most routine situations it is appropriate to do so), in unusual, dangerous, and stressful situations it is often better to consult other members of the team. Communication, up and down, is the glue that holds the bridge team together and ensures that all resources are effectively used. Many serious groundings could have been prevented by the simple exchange of information from crew to captain, information which, for reasons of tradition and mindless obedience to protocol, was not shared or was ignored.

A classic case of failure to observe principles of bridge team management occurred in 1950 when the USS Missouri, fully loaded and making over 12 knots at high tide, grounded hard on Thimble Shoals in Chesapeake Bay. The Captain ignored the advice of his Executive Officer, berated the helmsman for speaking out of turn, and failed to order a right turn into Thimble Shoals Channel. It took more than two weeks to free the ship.

Most transportation accidents are caused by human error, usually resulting from a combination of circumstances, and almost always involving a communications failure. Analysis of numerous accidents across a broad range of transportation fields reveals certain facts about human behavior in a dynamic team environment:

  • Better decisions result from input by many individuals
  • Success or failure of a team depends on their ability to communicate and cooperate
  • More ideas present more opportunities for success and simultaneously limit failure
  • Effective teams can share workloads and reduce stress, thus reducing stress-caused errors
  • All members make mistakes; no one has all the right answers
  • Effective teams usually catch mistakes before they happen, or soon after, and correct them

These facts argue for a more inclusive and less hierarchical approach to bridge team management than has been traditionally followed. The captain/navigator should include input from bridge team members when constructing the passage plan and during the pre-voyage conference, and should share his views openly when making decisions, especially during stressful situations. He should look for opportunities to instruct less experienced team members by involving them in debate and decisions regarding the voyage. This ensures that all team members know what is expected and share the same mental model of the transit.

Effective bridge teams do not just happen. They are the result of planning, education, training, practice, drills, open communication, honest responses, and management support. All of these attributes can and should be taught, and a number of professional schools and courses are dedicated to this subject. The U.S. Coast Guard web site at http://www.uscg.mil/STCW/m-achome.htm lists courses in Bridge Resource Management and other subjects that will help the navigator manage resources effectively.

2506. Standards of Training, Certification, and Watchkeeping (STCW)[edit]

From a personnel standpoint, the management of a military vessel is a very different proposition than a commercial vessel. Procedures are more formalized, lines of communication and responsibility are more structured, and the process of navigation is more highly organized. Military personnel are trained for navigational duties through a variety of required on-the-job and school-based training programs. The watch officer on a military vessel can generally be assured that the ratings under his command have passed the proper tests for their rank and are trained for their jobs. (Experience is another matter.)

The commercial captain has had, until recently, little such assurance. Training programs and certification for deck personnel only minimally addressed routine duties of bridge watchstanders, concentrating on emergency procedures and deck-related skills. The IMO’s International Convention on Standards of Training, Certification and Watchkeeping for Seafarers (STCW) of 1978 set certain qualifications for masters, mates, and watch personnel. It entered into force in 1984, and the United States became a party to this convention in 1991.

Between 1984 and 1992, significant limitations to the 1978 conventions became apparent. Vague requirements, lack of clear standards, limited oversight and control, and failure to address modern issues of watchkeeping were all seen as problems meriting a review of the 1978 agreement. Prior to this, the IMO had concentrated mostly on construction and equipment of ships. This new review, spearheaded by the U.S., was to concentrate on the human element, which in fact is the cause of most marine casualties. Three serious maritime casualties in which human factors played a part spurred the leadership of the IMO to immediate action, and in 1995, a year sooner than initially planned, the new convention was signed, and entered into force on February 1, 1997.

The U.S. Coast Guard immediately began the process of changing the regulations related to issuing licenses to U.S. maritime personnel to comply with the new guidelines. Mariners licensed under the 1978 convention had until February 1, 2002, to renew their documents under the old rule. All others would have to comply with the new standards. This date was subsequently amended to allow more time for compliance.

The provisions of STCW 95 strongly address the human element of bridge team management. They mandate maximum duty hours, minimum rest periods, and training requirements for specific navigational and communications systems such as ARPA and GMDSS. They require that officers understand and comply with the principles of bridge resource management. They require not merely that people be trained in certain procedures and operations, but that they demonstrate competence therein.

The competencies relating to navigation required of unlicensed personnel relate to general watchstanding duties. Such personnel must not only pass training, but must demonstrate competency in the use of magnetic and gyrocompasses for steering and course changes, response to standard helm commands, change from automatic to hand steering and back, responsibilities of the lookout, and proper watch relief procedures.

Competence may be demonstrated at sea or in approved simulators, and must be documented by Designated Examiners (DE’s) who provide documentation which will allow the examinee to be certified under the provisions of STCW 95.

VOYAGE PLANNING[edit]

2507. The Passage Plan[edit]

Before each voyage begins, the navigator should develop a detailed mental model of how the entire voyage is to proceed sequentially, from getting underway to mooring. This mental model will include charting courses, forecasting the weather and tides, checking Sailing Directions and Coast Pilots, and projecting the various future events—landfalls, narrow passages, and course changes—that will transpire during the voyage. This mental model becomes the standard by which he will measure progress toward the goal of a safe and efficient voyage, and it is manifested in a passage plan.

The passage plan is a comprehensive, step by step description of how the voyage is to proceed from berth to berth, including undocking, departure, enroute, approach and mooring at the destination. The passage plan should be communicated to the navigation team in a pre-voyage conference in order to ensure that all members of the team share the same mental model of the entire trip. This differs from the more detailed piloting brief discussed in Chapter 8, though it may be held in conjunction with it, and may be a formal or informal process.

Differences of opinion must be addressed. For example, one watch officer might consider a one mile minimum passing distance appropriate, while the captain prefers to pass no closer than two miles. These kinds of differences must be reconciled before the voyage begins, and the passage plan is the appropriate forum in which to do so.

Thus, each member of the navigation team will be able to assess the vessel’s situation at any time and make a judgement as to whether or not additional bridge resources are necessary. Passage planning procedures are specified in Title 33 of the U.S. Code, IMO Resolutions, 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, each applicable according to the individual situation.

Passage planning software can greatly simplify the process and ensure that nothing important is overlooked. A good passage planning software program will include great circle waypoint/distance calculators, tide and tidal current predictors, celestial navigational calculators, consumables estimators for fuel, oil, water, and stores, and other useful applications.

As the voyage proceeds, the navigator must maintain situational awareness to continually assess the progress of the ship as measured against the passage plan and the mental model of the voyage. Situational awareness consists of perceiving, comprehending, and comparing what is known at any given time with the mental model and passage plan. Both individual and team situational awareness are necessary for a safe voyage, and the former must be established by all members of the bridge team before the latter is possible.

The enemies of situational awareness are complacency, ignorance, personal bias, fatigue, stress, illness, and any other condition which prevents the navigator and his team members from clearly seeing and assessing the situation.

2508. Constructing a Voyage Track[edit]

Coastwise passages of a few hundred miles or less can be laid out directly on charts, either electronic or paper. Over these distances, it is reasonable to ignore great circle routes and plot voyages directly on Mercator charts.

For trans-oceanic voyages, construct the track using a navigational computer, a great circle (gnomonic) chart, or the sailings. It is best to use a navigational computer or calculator if one is available to save time and to eliminate the plotting errors inherent in transferring the track from a gnomonic to a Mercator projection. Because they solve problems mathematically, computers and calculators also eliminate rounding errors inherent in the tables, providing more accurate solutions.

To use a navigational computer for voyage planning, the navigator simply enters the two endpoints of his planned voyage or major legs thereof in the appropriate spaces. The program may ask for track segment intervals every X number of degrees. It then computes waypoints along the great circle track between the two endpoints, determines each track leg’s distance and, given a speed of advance, calculates the time the vessel can expect to pass each waypoint. The waypoints may be saved as a route, viewed on screen, and sent to the autopilot. On paper charts, construct the track on an appropriate Mercator chart by plotting the computer-generated waypoints and the tracks between them.

After adjusting the track as necessary to pass well clear of any hazard, choose a speed of advance (SOA) that ensures the ship will arrive on time at its destination or at any required point. If the time of arrival is open-ended, that is, not specifically required, choose a reasonable average SOA. Given an SOA, mark the track with the vessel’s first few planned hourly positions. In the Navy, these planned positions are points of intended movement (PIM’s). The SOA chosen for each track leg is the PIM speed. Merchant vessels usually refer to them as waypoints.

An operation order often assigns a naval vessel to an operating area. In that case, plan a track from the departure to the edge of the operating area to ensure that the vessel arrives at the operating area on time. Following a planned track inside the assigned area may be impossible because of the dynamic nature of an exercise. In that case, carefully examine the entire operating area for navigational hazards. If simply transiting through the area, the ship should still follow a planned and approved track.

2509. Following a Voyage Plan[edit]

Complete the planning discussed in Article 2508 prior to leaving port. Once the ship is transiting, frequently compare the ship’s actual position to the planned position and adjust the ship’s course and speed to compensate for any deviations. Order courses and speeds to keep the vessel on track without significant deviation.

Often a vessel will have its operational commitments changed after it gets underway. If this happens, it will be necessary to begin the voyage planning process anew.

VOYAGE PREPARATION[edit]

2510. Equipment Inventory[edit]

Prior to getting the ship underway, the navigator should inventory all navigational equipment, charts, and publications. He should develop a checklist of navigational equipment specific to his vessel and check that all required equipment is onboard and in operating order. The navigator should have all applicable Sailing Directions, pilot charts, and navigation charts covering his planned route. He should also have all charts and Sailing Directions covering ports at which his vessel may call. He should have all the equipment and publications required to support all appropriate navigational methods. Finally, he must have all technical documentation required to support the operation of his electronic navigation suite.

It is important to complete this inventory well before the departure date and obtain all missing items before sailing.

2511. Chart Preparation[edit]

Just as the navigator must prepare charts for piloting, he must also prepare his small scale charts for an open ocean transit. The following is the minimum chart preparation required for an open ocean or offshore coastal transit.

Correcting the Chart: Correct all applicable charts through the latest Notice to Mariners, Local Notice to Mariners, and Broadcast Notice to Mariners. Ensure the chart to be used is the latest announced edition.

Plotting the Track: Mark the track course above the track line with a “C” followed by the course. Similarly, mark each track leg’s distance under the course line with a “D” followed by the distance in nautical miles.

Calculating Minimum Expected, Danger, and Warning Soundings: Chapter 8 discusses calculating minimum expected, danger and warning soundings. Determining these soundings is particularly important for ships passing a shoal close aboard. Set these soundings to warn the conning officer that he is passing close to the shoal. Mark the minimum expected sounding, the warning sounding, and the danger sounding clearly on the chart and indicate the section of the track for which they are applicable.

Marking Allowed Operating Areas: (Military vessels) Often an operation order assigns a naval vessel to an operating area for a specific period of time. There may be operational restrictions placed on the ship while within this area. For example, a surface ship assigned to an operating area may be ordered not to exceed a certain speed for the duration of an exercise. When assigned an operating area, clearly mark that area on the chart. Label it with the time the vessel must remain in the area and what, if any, operational restrictions it must follow. The conning officer and the captain should be able to glean the entire navigational situation from the chart alone without reference to the directive from which the chart was constructed. Therefore, put all operationally important information directly on the chart.

Marking Chart Shift Points: Mark the chart points where the navigator must shift to the next chart, and note the next chart number.

Examining Either Side of Track: Highlight any shoal water or other navigational hazard near the planned track. This will alert the conning officer as he approaches a possible danger.

NAVIGATION ROUTINE AT SEA[edit]

2512. Fix Frequency[edit]

If ECDIS is in use, fix frequency is not an issue. The ship’s position will be displayed on the chart once per second, and the navigator need only monitor the process. If only an ECS is available, more careful attention is necessary since ECS cannot substitute for a paper chart. Nevertheless, it is reasonable to plot fixes at less frequent intervals when using an ECS, checking the system with a hand-plotted fix at prudent intervals.

Assuming that an electronic chart system is not available and hand-plotted fixes are the order of the day, adjust the fix interval to ensure that the vessel remains at least two fixes from the nearest danger. Choose a fix interval that provides a sufficient safety margin from all charted hazards.

Table 2512 below lists recommended fix intervals as a function of the phase of navigation:

Frequency Harbor/Appr. Coastal Ocean
3 min. or less 3-15 min. 30 min.

Table 2512. Recommended fix intervals.

Use all available fix information. With the advent of accurate satellite navigational systems, it is especially tempting to disregard this maxim. However, the experienced navigator never feels comfortable relying solely on one particular system. Supplement the satellite position with positions from Loran, celestial fixes, radar lines of position, soundings, or visual observations. Evaluate the accuracy of the various fix methods against the satellite position.

Use an inertial navigator if one is available. The inertial navigator may actually produce estimated positions more accurate than non-GPS based fix positions. Inertial navigators are completely independent of any external input. Therefore, they are invaluable for maintaining an accurate ship’s position during periods when external fix sources are unreliable or unavailable.

Always check a position determined by a fix, inertial navigator, or DR by comparing the charted sounding at the position with the fathometer reading. If the soundings do not correlate, investigate the discrepancy.

Chapter 7 covers the importance of maintaining a proper DR. It bears repeating here. Determine the difference between the fix and the DR positions at every fix and use this information to calculate an EP from every DR. Constant application of set and drift to the DR is crucial if the vessel must pass a known navigational hazard close aboard.

2513. Fathometer Operations[edit]

While the science of hydrography has made tremendous advances in the last few years, these developments have yet to translate into significantly more accurate soundings on charts. Further, mariners often misunderstand the concept of an electronic chart, erroneously thinking that the conversion of a chart to electronic format indicates that updated hydrographic information has been used to compile it. This is rarely the case. In fact, most electronic charts are simply digitized versions of the paper charts, newly compiled but based on the same sounding databases, which in some cases are more than a century old.

While busy ports and harbors tend to be surveyed and dredged at regular intervals, in less travelled areas it is common for the navigator to find significant differences between the observed and charted soundings. If in doubt about the date of the soundings, refer to the title block of the chart, where information regarding the data used to compile it may be found.

Standardized rules and procedures for the use of the depth sounder are advisable and prudent. Table 2513 suggests a set of guidelines for depth sounder use on a typical ship.

Water Depth Sounding Interval
< 10 m Monitor continuously.
10 m - < 100 m Every 15 minutes.
100 m - < 300 m Every 30 minutes.
> 300 m Every hour.

Table 2513. Fathometer operating guidelines.

2514. Compass Checks[edit]

Determine gyro compass error at least once daily and before each transit of restricted waters. Check the gyro compass reading against the inertial navigator if one is installed. If the vessel does not have an inertial navigator, check gyro error using a flux gate magnetic or ring laser gyro compass, or by using the celestial techniques discussed in Chapter 17.

The magnetic compass, if operational, should be adjusted regularly and a deviation table prepared and posted as required (See Chapter 6). If the magnetic compass has been deactivated in favor of a digital flux gate magnetic, ring laser gyro, or other type of electronic compass, the electronic compass should be checked to ensure that it is operating within manufacturer’s specifications, and that all remote repeaters are in agreement. Note that the electronic compass must not be in the ADJUST mode when in restricted waters.

2515. Night Orders and Standing Orders[edit]

The Night Order Book is the vehicle by which the captain informs the officer of the deck of his orders for operating the ship. It may be in hardcopy or softcopy format. The Night Order Book, despite its name, can contain orders for the entire 24 hour period for which the Captain or Commanding Officer issues it.

The navigator may write the Night Orders pertaining to navigation. Such orders include assigned operating areas, maximum speeds allowed, required positions with respect to PIM or DR, and, regarding submarines, the maximum depth at which the boat can operate. Each department head should include in the Night Order book the evolutions he wants to accomplish during the night that would normally require the captain’s permission. The captain can add further orders and directions as required.

The Officer of the Deck or mate on watch must not follow the Night Orders blindly. Circumstances under which the captain signed the Orders may have changed, rendering some evolutions impractical or impossible. The Officer of the Deck, when exercising his judgment on completing ordered evolutions, must always inform the captain of any deviation from the Night Orders as soon as such a deviation occurs.

While Night Orders are in effect only for the 24 hours after they are written, Standing Orders are continuously in force. The captain sets the ship’s navigation policy in these orders. He sets required fix intervals, intervals for fathometer operations, minimum CPA’s, and other general navigation and collision avoidance requirements.

2516. Watch Relief Procedures[edit]

When a watch officer relieves as Officer of the Deck or mate on watch, he assumes the responsibility for the safe navigation of the ship. He becomes the Captain’s direct representative, and is directly responsible for the safety of the ship and the lives of its crew. He must prepare himself carefully prior to assuming these responsibilities. A checklist developed specifically for each vessel can serve as a reminder that all watch relief procedures have been followed. The following list contains those items that, as a minimum, the relieving watch officer must check prior to assuming the navigation watch.

  • Conduct a Pre-Watch Tour: The relieving watch officer should tour the ship prior to his watch. He should familiarize himself with any maintenance in progress, and check for general cleanliness and stowage. He should see that any loose gear that could pose a safety hazard in rough seas is secured.
  • Check the Position Log and Chart: Check the type and accuracy of the ship’s last fix. Verify that the navigation watch has plotted the last fix properly. Ensure there is a properly constructed DR plot on the chart. Examine the DR track for any potential navigational hazards. Check ship’s position with respect to the PIM or DR. Ensure that the ship is in the correct operating area, if applicable. Check to ensure that the navigation watch has properly applied fix expansion if necessary.
  • Check the Fathometer Log: Ensure that previous watches have taken soundings at required intervals and that the navigation watch took a sounding at the last fix. Verify that the present sounding matches the charted sounding at the vessel’s position.
  • Check the Compass Record Log: Verify that the navigation watch has conducted compass checks at the proper intervals. Verify that gyro error is less than 1° and that all repeaters agree within 1° with the master gyro.
  • Read the Night Orders: Check the Night Order Book for the captain’s directions for the duration of the watch.
  • Check Planned Operations and Evolutions: For any planned operations or evolutions, verify that the ship meets all prerequisites and that all watchstanders have reviewed the operation order or plan. If the operation is a complicated one, consider holding an operations brief with applicable watchstanders prior to assuming the watch.
  • Check the Broadcast Schedule: Read any message traffic that could have a bearing on the upcoming watch. Find out when the last safety and operational messages were received. Determine if there are any required messages to be sent during the watch (e.g. position reports, weather reports, Amver messages).
  • Check the Contact Situation: Check the radar picture (and sonar contacts if so equipped). Determine which contact has the nearest CPA and what maneuvers, if any, might be required to open the CPA. Find out from the off-going watch officer if there have been any bridge-to-bridge communications with any vessels in the area. Check that no CPA will be less than the minimum set by the Standing Orders.
  • Review Watchstander Logs: Review the log entries for all watchstanders. Note any out-ofspecification readings or any trends in log readings indicating that a system will soon fail.

After conducting these checks, the relieving watch officer should report that he is ready to relieve the watch. The watch officer should brief the relieving watch officer on the following:

  • Present course and speed
  • Present depth (submarines only)
  • Evolutions planned or in progress
  • Status of the engineering plant
  • Status of any out-of-commission equipment
  • Orders not noted in the Night Order Book
  • Status of cargo
  • Hazardous operations planned or in progress
  • Routine maintenance planned or in progress
  • Planned ship’s drills
  • Any individuals working aloft, or in a tank or hold
  • Any tank cleaning operations in progress

If the relieving watch officer has no questions following this brief, he should relieve the watch and announce to the rest of the bridge team that he has the deck and the conn. The change of watch should be noted in the ship’s deck log.

Watch officers should not relieve the watch in the middle of an evolution or when casualty procedures are being carried out. This ensures that there is watchstander continuity when carrying out a specific evolution or combating a casualty. Alternatively, the on-coming watch officer might relieve only the conn, leaving the deck watch with the off-going officer until the situation is resolved.