Watchkeeping during ocean passages
Watchkeeping during ocean passages will require all the activities related to performing a navigational watch as discussed previously. In addition, priority is given to the following
During ocean passages, the principle threat to a vessel is the risk of collision. It of utmost importance that an approaching vessel is detected early and avoiding action is taken in sufficient time. The emphasis therefore must be given to keeping an efficient lookout.
Colregs Rule 5 states:
Every vessel shall at all times maintain a proper look out by sight and by hearing as well as by all available means appropriate to the prevailing circumstances and conditions so as to make a full appraisal of the situation and the risk of collision.
Priorities between visual lookout and radar lookout vary under different conditions of visibility.
Electronic Navigation Aids
When out of the sight of land, the navigational accuracy depends greatly on instruments. It is therefore necessary that the officer of the watch monitors the equipment and ensures its accuracy. During each watch, principal instruments directing the navigation of the ship should be checked with other sources of position fixing as well as with estimated position. Any deviation detected should be investigated and corrected.
Gyro compass is more commonly used to steer the vessel during ocean passages. It is therefore important to check the compass error, compare the compasses and monitor the courses steered.
In case of failure of electronic navigational aids, the only recourse a navigator has, to fix his vessel’s position, is with the help of celestial bodies. There is therefore a need to practice this art. Learn to calculate position based on this observation as accurately as possible and cross check positions obtained from electronic navigational aids.
Coastal passage and congested waters
During coastal passage, the 00W is generally busy plotting the vessel’s position, manoeuvring the vessel when required, to avoid collision and to alter the course as per passage plan. He therefore has little time to do other duties not related to navigation. Time management becomes very essential to ensure that all the navigational tasks are carried out at the appropriate time and in accordance with the required accuracy and efficiency.
Where the 00W has to plot the ship’s position, he shall ensure that the lookout is alert. He shall also assess the situation around him and avoid being absent when ships are approaching and a risk of collision is present. This again calls for planning so that collision avoidance and position fixing get equal priority. In cases when the 00W finds it difficult to manage both, he should not hesitate to call the Master. 00W must understand that calling for assistance is not a sign of inefficiency.
Continuous monitoring of vessel’s position for safe navigation and collision avoidance is of equal importance. The officer of the watch will therefore have to understand how to set the priorities and how to manage time.
In coastal waters, the navigator has to allow for:
- Navigation in close proximity to navigational hazards viz. shallow waters, oil fields, etc. This is best done when these are marked out conspicuously when passage planning. a Strong tidal currents;
- Compliance with traffic separation schemes or prohibited zones;
- Changes in the way the position is ascertained
- Identification of land marks and the navigational aids;
- Plotting of position frequently and comparing the same with various methods available
- Adjustment of courses to allow for deviations;
- Increase in traffic density including the presence of fishing vessels and or sailing vessels
- Necessity of hand steering and therefore the additional requirement of a stand-by seafarer on or off the bridge.
- Reports to be made to VTS, where required; a Take avoiding action such that sufficient depth is maintained under keel. Plan in advance to ensure vessel does not come in close proximity to other navigational hazards. Note: -vessel’s draft increases in direct proportion to the cube of the speed and the depth of the water.
- Be prepared to use the engines if necessary, to ensure adequate sea room.
- Use the largest scale chart suitable for that area and corrected up-to-date
- Plot vessel’s position at regular intervals and more frequently when in confined waters. The position shall be compared with the estimated position.
- Adjust course if vessel is found to have deviated from the planned track due to any cross track error
- Take a fix at every alteration of course and at regular intervals thereafter,
- Check soundings and log at regular intervals, record them.
- Where navaids are available, vessel’s position to be fixed by using more than one method.
- Where necessary allow for set and drift to keep vessel on the planned track.
- Identify positively all relevant navigational marks.
- Call the Master before a potentially dangerous situation becomes critical
- Study the chart and expect to pick up landmarks before they are actually seen.
Maintaining a navigation watch in pilotage waters
It is expected that the passage plan be made from berth to berth. Where the port is not so well known, the information relating to port passage should be obtained from the pilot. Unfortunately, it is not always so easy. However watching the pilot’s navigational process sufficient information could be recorded to be use the next time.
The 00W should note that despite the duties and obligations of the pilot, his presence on board does not relieve the Master or officer in charge of the navigational watch from their duties and obligations for the safety of the ship.
The Master and the pilot should exchange information regarding navigation procedures, local conditions and the ship’s characteristics.
The Master and/or the officer in charge of the navigational watch shall co-operate fully with the pilot and maintain an accurate check on the ship’s position and movement.
Monitoring also includes checking of the courses steered, the helm movements when the vessel is under the pilot’s advise.
Informatively, when under pilot’s advice, if the 00W is in any doubt as to the pilot’s actions or intentions, he should seek clarification from the pilot. If any doubt still exists, he should notify the Master immediately and take whatever action is necessary before the Master arrives.
Proceeding to sea
Upon departure from a port, course is set for the next waypoint in accordance with the passage plan. Normally the duty officer takes over at this juncture.
The 00W shall, in no circumstances, leave the bridge until properly relieved. He shall continue to be responsible for the safe navigation of the ship, even if the Master is present on the bridge, until informed specifically that the Master has assumed that responsibility and this is mutually understood. Even when the Master is in charge, he shall notify the Master when in any doubt and take action as directed.
Watchkeeping under adverse conditions
Whenever vessels are in sight of one another, a good method of early detection of risk of collision is by taking compass bearings of the approaching vessel. No appreciable change in the compass bearing is an indication that the two vessels may be progressively closing in towards each other and a risk of collision may exist. The 00W shall therefore take frequent and accurate compass bearings of approaching vessels. He should, however, bear in mind that such risk may sometimes exist even when an appreciable bearing change is evident, particularly when approaching a very large ship or a tow or approaching a ship at close range. These bearings shall be recorded and a radar plot used to assess the risk.
The 00W shall take early and positive action in compliance with the applicable Colregs 1972 (Colregs Parts A and B) and subsequently check that such action is having the desired effect.
In clear weather, whenever possible, 00W shall carry out radar practice. Such practice may include:
- Plotting bearing and distance off and comparing it with visual observation,
- Using parallel index when passing off land marks or even ships to ensure that they are at pre-determined distances
- Familiarisation with the controls without looking at them.
- Even where ARPA is carried the aspect of the vessel and the CP shall be calculated and compared with the ARPA readings.
Restricted visibility due to fog, rain, snow, sand storm, squall or any other similar reasons makes it difficult to identify the presence of other vessels in vicinity. Even after their presence is detected, such weather conditions make it difficult to see how the vessels are heading. The weather therefore needs to be monitored and visibility assessed regularly.
Use of radar is a must in restricted visibility. When approaching a fog bank or rain squall, radar should always be switched on.
Systematic plotting of detected targets shall be started at the earliest.
Long range scanning shall be carried out from time to time to get an early warning of approaching vessels.
When using radar in restricted visibility, it should be borne in mind that rain and snow are two conditions, which reduce significantly the ability of radar to detect targets. If two radars are fitted, both S band and X band should be operational.
If only one radar is fitted and is being used by two operators, there is a chance that some change in settings may be made by one of the operators. Where this goes unnoticed by the other operator, it could lead to an error of judgement.
Verification of range scale and a check of data input manually shall be carried out every time each operator observes the radar screen.
Navigation lights shall be displayed in accordance with Colregs Part C and sound signals used in accordance with Colregs Rule 35 by vessels operating in restricted visibility. Small vessels and crafts, operating in vicinity, and not Fitted with Radar know of the presence of a vessel by hearing the sound signal alone.
Lookout should be posted to detect the presence of other vessels by sight as well as by hearing. There is however more uncertainty about the movement of target vessels in restricted visibility. For example, the sound signals prescribed by Colregs for a vessel engaged in fishing and a vessel not under command is same. It is therefore very important that if any action is required, it is taken early to avoid a close quarter situation.
Master is invariably called when there is reduced visibility. There is always a danger of presence of a hidden target at close range as the vessel enters the restricted visibility area. Master should therefore be called as early as practicable prior to onset of reduced visibility.
In restricted visibility, applicable Colregs is Rule 19. Use the helm and engines to avoid a potential risk of collision. The helmsman should be called and steering should be put to hand. The engines should be put to standby and vessel, brought to safe speed.
Maintaining a navigational watch at sea by the 00W in restricted visibility shall therefore include the following activities:
- Observe the weather and call the Master when visibility deteriorates
- Post lookouts
- Stop descaling or other similar maintenance activity on deck to facilitate hearing of weak sound signals coming from a distance
- Switch on navigation lights
- Comply with sound signals of Colregs Rule 35
- Switch radar ON
- Monitor traffic in the area. Plot targets systematically
- Put engines to stand-by; bring the ship to safe speed, ready to manoeuvre where necessary.
- Switch over to manual or hand steering.
- Be prepared to further reduce or stop engines or use helm to get out of danger.
- Take avoiding action early.
- Close watertight doors
Maintaining a navigational watch in hours of darkness
During hours of darkness, navigation lights indicate not only the presence of other vessels but also indicate the type of such vessel and the direction in which they are heading.
Navigation lights shall be displayed in accordance with Colregs Part C; however, vessels have been known to collide with floating containers, derelicts and other similar unlit hazards. When operating in vicinity of oilfields precautions are necessary as some platforms may be unattended and therefore unlit. Use of radar equipment must be made during hours of darkness.
The Master and the 00W, when arranging / assigning lookout duty to seafarers shall have due regard to the bridge equipment and navigational aids available for use and their limitations. The lookout shall be instructed as to what he is expected to encounter.
Use of Radar Equipment
Maintaining a navigational watch at sea includes use of the radar. The radar shall be switched ON, tuned and kept ready on stand by if it is not required at a particular time The radar shall be switched on
- When reduced visibility is expected or encountered,
- When Rain/fog bank is seen approaching,
- When a vessel is in sight and its course, speed and CPA is not known.
- For fair weather practice, and
- During hours of darkness.
When using radar, the 00W shall have due regard to its limitations and shall bear in mind the necessity to comply at all times with the provisions on the use of radar contained in Colregs 1972.
Whenever radar is in use the 00W shall select an appropriate range scale and observe the display carefully. He shall ensure that plotting or systematic analysis is commenced in ample time.
The 00W shall ensure that range scales employed are changed at sufficiently frequent intervals so that echoes are detected as early as possible. It shall be borne in mind that small or poor echoes escape detection and therefore a good lookout must be maintained.
Over reliance on Radar
Radar has some distinct advantages over the eye. These include factors such as –
- Greater visibility range,
- Detection of unlit objects,
- Accurate range information,
- Facility of parallel indexing,
- Useful in predicting course, speed and CPA of target,
- Useful in restricted visibility,
These advantages sometimes lead to over reliance on radar and neglect of visual lookout.
Relying implicitly on any equipment must be avoided. The radar may have developed defects. There may be error in setting up and therefore may not be totally reliable. In addition some poor radar targets may not be detected except at very close range. Some small targets may not be detected by radar at all.
To minimize the risk of error, the 00W therefore should check the radar with the visual observations regularly. This can best be done in good visibility. it will mean not only increase in proficiency in its use but also confidence in the reliability of the observations made.
When ARPA is being used, the tracking and information about the acquired targets will be lost if you put radar on standby. You will have to reacquire targets when you put the radar is switched ON.
Calling the Master
Navigation of the ship is a collective responsibility of all the watch keepers and the Master. Every 00W has the responsibility to ensure safe navigation during his duty hours but the Master has the ultimate responsibility for safe and efficient navigation of the vessel.
He is the most experienced navigator on board. He therefore has a better grasp of all the situations which the comparatively inexperienced but duly qualified 00W cannot have. The Master probably would have dealt with most of the situations in the past.
Bridge Team management provided to you as a text suggests and the Company’s Manual requires the Master to be called to the bridge in various difficult circumstances. Through “Standing orders,” Night orders” and “Verbal instructions” every Master defines his requirements when he is to be called to the bridge.
Junior officers are often concerned that they might be inconveniencing the Master by calling him to the bridge, especially during odd hours when he is taking rest.
Remember invariably “CALL WHEN IN DOUBT” be assured that the master shall never be annoyed if you call him for what appears to be trivial.
It must be remembered that a Master has more confidence in an 00W who demonstrates willingness to call him when in doubt rather than in those who allow dangerous situation to be developed and then call him at the last minute.
Here again expressing a doubt is not a reflection on the competency or efficiency of the 00W. Always remember that two heads are better than one.
Here I remember an incidence when I was young cadet keeping my first few watches.
Heading on a course of 090° a bright light coming over the horizon was observed. The lookout that was on the forecastle also rang one bell to indicate the light on the starboard bow. The Radar was on but there was no target on the Radar. I sweated it out for a few minutes but seeing the brightness of the light called the Master. He came up checked everything and said Son, take a bearing and work out the amplitude of Venus.’ I almost kicked myself but the Master said, “don’t worry son that’s why I am here. If in doubt call”
There are many guidelines as to when to call the Master. The bridge procedures guide published by the ICS, the company’s navigation manual and the Master’s night order book all identify specific instances when to call the Master. All these publications and guidelines or orders are actually telling you to call the Master whenever you are in doubt and not to wait till the last moment.
Navigation is the art and science of knowing where the ship is at any given moment and to determine whether she is proceeding in the right direction at all times. Fixing of position is therefore very important and there needs to be no neglect in this primary duty.
Remember when driving along the road you can afford to miss a turning but this is not permissible when the ship is at sea. The turning that you miss may be your final passage on to a reef or shallow patch.
Remember, therefore, to take a fix at every alteration of course and at frequent intervals thereafter to check that the vessel is actually following the course correctly. At each of the position fixed you should ascertain the Cross-course made good and speed made good. Invariably the fix obtained by on nav aid should be coss-checked by using another nav-aid
Checking the fix
Whenever you fix position on the chart there are certain checks that should invariable be made. They are:
- Is the course and distance made good between the last fix and this fix is consistent with the speed and the course the ship is actually performing?
- Have I used the correct chart for plotting and identified the correct nav aids? (In some areas all Racons have the same identification signals)
- When changing over a chart have I plotted the position correctly? It is prudent to plot the position by latitude and longitude and transfer the same to the next chart. d. Have I verified the position by one more method?
- Have I checked the sounding and compared it with the position obtained.
This is carried out by a variety of methods. We have covered this in more details in modules relating to the terrestrial and the celestial navigation.
Where possible, practice celestial navigation regularly. Compare the positions so obtained with those obtained from electronic navigational aids. It is not advisable to rely on positions obtained by one system alone.
In depths of less than 200 meters use the echo sounder. Obtain soundings frequently and every time when a position is fixed. Compare soundings with the charted positions for discrepancy. Investigate errors, if any Log soundings at least every halt-hour and more frequently in shallower waters.