COLREGs 1972: Made Easy
About this Made Easy
It’s our pleasure to introduce to mariners this ‘Made Easy’ on RoR. We felt the necessity of an abridged version of RoR-explanation for the benefit of the mariners, especially for junior deck officers. By publishing this Made Easy, a dream has come true; the complete work has not been accomplished yet though. We’ve prepared it based on own expertise and long research works. We’ve, so far, covered Rule-1 to Rrule-19 and intend to add the remaining rules soon.
Moreover, we intend to publish a book on this in future. We’ve tried our best to prepare it without mistakes. However, no write-up is flawless. We would appreciate your feedback on how to improve this Made Easy. Please advise us if you find any mistakes in this Made Easy. No person or organization is allowed to copy or reproduce the contents of this Made Easy without prior permission from the writers. Your feedback is our inspiration. Please send your feedback to [email protected] .
Preface
The International Regulations for Preventing Collisions at Sea 1972 (Colregs) are published by the International Maritime Organization (IMO) and set out, among other things, the "Rules of the Road" or navigation rules to be
followed by ships and other vessels at sea to prevent collisions between two or more vessels. The COLREGs are derived from a multilateral treaty called the ‘Convention on the International Regulations for Preventing Collisions at Sea’.
History
Prior to the development of a single set of international rules and practices, there existed separate practices and various conventions and informal procedures in different parts of the world, as advanced by various maritime nations. As a result, there were inconsistencies and even contradictions that gave rise to unintended collisions. Vessels’ navigation lights for operating in darkness as well as navigation marks also were not standardized, giving rise to dangerous confusion and ambiguity between vessels at risk of colliding. 1840 in London, the Trinity House drew up a set of regulations which were enacted by Parliament in 1846.
1858 in the UK, coloured sidelights were recommended for sailing vessels and fog signals were required to be given by steam vessels on the ships whistle and by sailing vessels on the fog horn or bell, while a separate but similar action was also taken in the United States.
In 1863, a new set of rules drawn up by the British Board of Trade, in consultation with the French government, came into force.
By 1864, the regulations (or Articles) had been adopted by more than thirty maritime countries, including Germany and the United States.
In 1867, Thomas Gray, assistant secretary to the London Maritime
Department of Trade, wrote The Rules of the Road, a pamphlet that became famous for its well-known mnemonic verses.
In 1880, the 1863 Articles were supplemented with whistle signals and in 1884 a new set of international regulations was implemented.
In 1889, the United States convened the first international maritime
conference in Washington, D.C. The resulting rules were adopted in 1890 and came into effect in 1897.
Some minor changes were made during the 1910 Brussels Maritime
Conference and some rule changes were proposed, but never ratified, at the 1929 International Conference on Safety of Life at Sea (S.O.L.A.S.) with the recommendation that the direction of a turn be referenced by the rudder instead of the helm or tiller being informally agreed by all maritime nations in 1935.
The 1948 S.O.L.A.S. International Conference made several
recommendations, including the recognition of R.A.D.A.R., these were eventually ratified in 1952 and became effective in 1954.
Further recommendations were made by a S.O.L.A.S. Conference in London in 1960 which became effective in 1965
The International Regulations for Preventing Collisions at Sea were adopted as a Convention of the International Maritime Organization on 20 October 1972 and entered into force on 15 July 1977. They were designed to update and replace the Collision Regulations of 1960.
Amendments
1981: Rule 10 was amended with regard to dredging or surveying in traffic separation schemes.
1987: In 1987 amendments were made to several rules, including rule 1(e) for vessels of special construction; rule 3(h), vessels constrained by her
draught and Rule 10(c), crossing traffic lanes.
1989: In 1989 Rule 10 was altered to stop unnecessary use of the inshore traffic zones associated with TSS.
1993: In 1993 amendments were made concerning the positioning of lights on vessels.
2001: In 2001 new rules were added relating to wing-in-ground-effect (WIG) craft
2007: In 2007 the text of Annex IV (Distress signals) was rewritten
Purpose of this write-up
There are many implied and expressed terms in RoR. A good understanding of RoR is possible only when a learner comprehends those terms clearly. We have mainly emphasized on the explanation of criticality of rules and some words which are usually misunderstood by a learner. Learning the rules by heart has an advantage of getting them at finger tips but one should aim for understanding them thoroughly to be able to take correct decisions
whenever a risk of collision exists or deemed necessary.
We shall also discuss about some situations and their correct actions to co-relate them with usual Oral Questions.
Reference & Publications
RoR have connections with IMO, Section A-VIII/2 of the STCW Code,
SOLAS’74, International Code of Signals, IAMSAR, IMO Ship’s Routing Guide and GMDSS Regulations.
Absolute ‘Right of Way’
A commonly held misconception concerning the rules of marine navigation is that by following specific rules, a vessel can gain certain rights of way over other vessels. No vessel ever has absolute "Right of Way" over other vessels. Rather, there can be a "Give Way" (burdened) vessel and a "Stand on"
(privileged) vessel, or there may be two give way vessels with no stand on vessel. A stand on vessel does not have an absolute right of way over any give way vessel, for if there is a risk of collision, a stand on vessel may still be obliged under Rule 2 to give way so as to avoid it, if doing so will be effective and is practicable. Two power-driven vessels approaching each other head to head are both deemed to be "Give Way" and both are required to alter course so as to avoid colliding with the other. Neither vessel has "Right of Way".
Expressed and Implied Terms
Expressed Terms: These terms are defined in Rule 3.
words have not been stipulated in RoR. However, if we try to understand them thoroughly, we can clearly comprehend their meanings. We have discussed about them in appropriate paragraphs.
RoR Overview P G P S S C A V S C S A R G R
P L P S S P E A S R R R R A
Part A - General
Rule-1: Application
(a)These Rules shall apply to all vessels upon the high seas and in all waters connected therewith navigable by seagoing vessels.
Inland Waters: Inland waters that are not connected with high seas may be regulated by ‘Rules for Inland Waters’ derived by government of a particular state or country. As an example in Bangladesh, RoR apply in the navigable waters of ‘Karnaphuli River’ but not in other rivers that are connected to it but are neither not connected with high seas nor navigable by seagoing vessels.
(b) Nothing in these Rules shall interfere with the operation of special rules made by an appropriate authority for roadsteads, harbours, rivers, lakes or inland waterways connected with the high seas and navigable by seagoing vessels. Such special rules shall conform as closely as possible to these Rules.
Roadsteads: A sheltered area outside a harbour where a ship can lie safe at anchor, also known as a roads.
Harbour: A harbor or harbour, or haven, is a place where ships may shelter from the weather or are stored. Harbours can be man-made or natural. Special Rules: They are made by a particular state or government. Usually, they are made in close conformance with RoR.
(c) Nothing in these Rules shall interfere with the operation of any special rules made by the Government of any State with respect to additional station or signal lights, shapes or whistle signals for ships of war and vessels
proceeding under convoy, or with respect to additional station or signal lights, or shapes for fishing vessels engaged in fishing as a fleet. These additional station or signal lights, shapes or whistle signals shall, so far as possible, be such that they cannot be mistaken for any light, shape or signal authorized elsewhere under these Rules.
Three types of vessels: Warships, Vessels proceeding under convoy and a fishing fleet engaged in fishing.
Degree of Special Rules: These rules are usually more stringent than RoR. Additional Station: It may be an additional mast fitted with signal lights and/or shapes.
Fishing vessels engaged in fishing as a fleet: These are different from the vessels mentioned in Annex-II and Rule-26(d): A vessel engaged in fishing in close proximity to other vessels engaged in fishing.
(d) Traffic separation schemes may be adopted by the Organization for the purpose of these Rules.
The Organization: This is the International Maritime Organization (IMO), a body of the United Nations. Rule 1(d) authorizes IMO to adopt traffic separation schemes to which Rule 10 will apply. The details of TSS can be found in “IMO Ships’ Routeing Guide’’.
TSS: As defined by IMO Ships’ Routeing Guide, ‘A routeing measure aimed at the separation of opposing streams of traffic by appropriate means and by the establishment of traffic lanes’.
(e) Whenever the Government concerned shall have determined that a vessel of special construction or purpose cannot comply fully with the
provisions of any of these Rules with respect to the number, position, range or arc of visibility of lights or shapes, as well as to the disposition and
characteristics of sound-signaling appliances, such vessel shall comply with such other provisions in regard to the number, position, range or arc of visibility of lights or shapes, as well as to the disposition and characteristics of sound-signaling appliances, as her Government shall have determined to be the closest possible compliance with these Rules in respect of that vessel. Deviation from Lights & Shapes: Some specially constructed vessels’ unique functions may be impaired if these rules are complied with fully. In those cases, Rule 1(e) permits a deviation from the navigation light, shape, or sound-signal requirements but only to the point of preventing interference with the special function.
Special Vessels’ Lights: Information about lights and shapes of special vessels such as Warships,
Aircraft Carriers and Submarines can be found in Mariners’ Handbook, Annual Summary of
Rule -2: Responsibility
(a)Nothing in these Rules shall exonerate any vessel, or the Owner, Master or crew thereof, from the consequences of any neglect to comply with these Rules or of the neglect of any precaution which may be required by the ordinary practice of seaman, or by the special circumstances of the case. Exonerate: Does not relieve
Neglect to comply with these Rules: A vessel does not display appropriate lights and shapes required by RoR.
Neglect to comply with any precaution: These precautions may be required by good seamanship or special circumstances. The Rules are written for usual or likely situations; atypical situations are termed "special
circumstances." A complete list of special circumstances is, of course, impossible to provide. A number of examples should give some idea of the term's meaning.
Vessels proceeding stern-first are considered to be in special circumstances A vessel is expected to keep clear of an anchored vessel or a vessel not under command
Vessels not making way may be in special circumstances. First, a vessel should avoid stopping in a high-traffic area, and when a vessel decides to stop, it should make its intentions clear to other vessels in the area. As always, a proper lookout should be maintained.
A drifting vessel should not expect that other vessels will keep clear of her unless she displays proper lights and shapes for a vessel NUC.
If a vessel is drifting, its course may not be obvious. If the stopped vessel is large, it may not be able to move out of the way of a fast oncoming vessel. Whatever the "if" of the situation, encounters with vessels not making way through the water deserve extra caution.
A vessel must not proceed in dense fog if her radars are not functional, rather she should stay at anchorage till her radars are repaired or fog disperses.
Another special circumstance occurs when two vessels have managed to get themselves much too close to each other and are headed in unfortunate directions. Collisions about to happen are often called "extremis" situations. The vessels involved are said to be "in extremis."
When two vessels approach one another at a difficult bend in a tidal river it’s a good practice that the one having the tide against her to wait until the other has passed. This is because a vessel against the tide has better maneuverability and can hang out for sometimes with
controlled engine movements or she can even drop her anchor for the interest of avoiding collision.
An extremis (imminent danger situation) situation occurs when a collision can be avoided only by the action of both vessels. Here Rule 17(b) requires the stand-on vessel to maneuver to avoid the collision.
In shallow waters, a vessel is likely to experience Squat and Interaction. Squat causes bodily sinkage to a vessel and change of trim which
consequently causing reduction of speed and/or grounding. Interaction can cause bow cushon or bank suction or smelling the ground, consequently causing grounding, collision, turbulence to other vessels at berth, etc. To avoid all these dangers, the good seamanship is to reduce speed and proceed with caution.
In an extremis situation, the operators on one or both of the vessels have failed to take the first line of preventive actions prescribed by the Rules. The second line of defense comes into play; the parties in extremis situation are required to do whatever is necessary to avoid a collision or at least to
minimize the damage.
The physical limitations of the vessels may also impose special
circumstances. Draft limitations will prevent some give-way vessels from turning into shallow water; a sluggish craft may preclude a timely maneuver for others.
(b) In construing and complying with these Rules due regard shall be had to all dangers of navigation and collision and to any special circumstances, including the limitations of the vessels involved, which may make a departure from these Rules necessary to avoid immediate danger. Construe: It means explain.
Dangers of navigation: A vessel is unable to alter her course due to the presence of shallow water although she is required to do so in compliance with some rules (Rule-14, 15 etc.).
Dangers of Collision: On a head-on situation, a vessel is unable to alter her course to starboard due to the presence of another vessel on her starboard side. This way she is unable to comply with Rule-14.
Special Circumstances & Immediate danger: Mentioned below. A departure is only permitted when there are special circumstances and there is immediate danger. The departure must be of such a nature as to avoid the danger which threatens.
Embarking and disembarking pilots could be considered as special
circumstances since maneuvering of both vessels may expose both the pilot vessel and the pilot to danger.
Limitation of a vessel: Vessel in a convoy may have limitations to alter course in a crossing situation. Action taken in accordance with the advice to avoid a squadron or convoy on the port bow would not be a departure from the Rules if executed at long range before risk of collision begins to apply Departure from these rules: Rule 2 is an overriding rule, often called the "Rule of Good Seamanship". Strict literal compliance with the Rules may not be a defense if a collision occurs. Rule 2 holds the mariner responsible not only for complying with the Rules but also for avoiding collisions. Merely complying with the Rules is not enough. If, in fact, strict compliance with the Rules would result in immediate danger, a departure from the Rules (to the extent necessary to avoid the danger) is required. A mariner who chooses to adhere strictly to the word of the Rules, and thereby causes or fails to avoid a collision that could have been prevented by other action, may not use compliance with the Rules as a defense to liability.
A departure is under Rule-2(b) is justified only if necessary to avoid
immediate danger. Both necessity and immediate danger must be present. Your responsibility is not only to follow the COLREGs – you are also
responsible for doing everything necessary to avoid the risk of collision and the dangers of navigation.
Rule-3: General Definitions
(a)The word ‘vessel’ includes every description of water craft, including non-displacement craft, WIG craft and seaplanes, used or capable of being used as a means of transportation on water.
Vessels: All vehicles that operate on the water are vessels, including displacement craft (those that "float" or are supported by the static buoyancy derived from the water that their hulls displace)
Non-displacement crafts: These are supported by the dynamic lift of hydrofoils or other lifting surfaces.
Seaplanes: A seaplane is a powered fixed-wing aircraft capable of taking off and landing (alighting) on water.
"Used or capable of being used as a means of transportation": This phrase implies the practical transportation of people or cargo. Inner tubes are not included, although sailboards are.
“WIG craft”: A Wig Craft is a multimodal craft which, in its main operational mode, flies by using ground effect above the water or some other surface, without constant contact with such a surface and supported in the air, mainly, by an aerodynamic lift generated on a wing (wings), hull, or their parts, which are intended to utilize the ground effect action.
(b) The term ‘power-driven vessel’ means any vessel propelled by machinery. Propelled by machinery: Vessels propelled by oars, paddles are not included in this definition. Vessels propelled by machinery as well as any other means of propulsion are considered to be power-driven vessels. A day shape is required for most vessels using both sails and machinery for propulsion; see Rule 25(e).
(c) The term ‘sailing vessel’ means any vessel under sail provided that propelling machinery, if fitted, is not being used.
Propelling Machinery: Operation of the engine to generate electricity or to heat water, does not make the sailing vessel a power-driven vessel, so long as the propeller (or paddle wheel) is not engaged.
(d) The term ‘vessel engaged in fishing’ means any vessel fishing with nets, lines, trawls or other fishing apparatus which restrict maneuverability, but does not include a vessel fishing with trolling lines or other fishing apparatus which do not restrict maneuverability.
A fishing vessel: This is a vessel used for catching fish, whales, seals, walrus or other living resources of the sea.( (SOLAS I/2)). If a fishing vessel is not engaged in fishing she should display lights and shapes as per Rule-26(e). Restrict maneuverability: Not all fishing gears restrict maneuverability. Study Mariner’s
Handbook for the details of pictorial fishing gears used by vessels engaged in fishing.
Lines: The term ‘lines’ refers to lines such as long-lines which may be miles long and to which are attached at regular intervals many leaders and hooks. Trawls: The term ‘trawls’ refers to large open-mouthed nets that are towed through the water by one or two specially equipped fishing vessels
(trawlers).
Vessels fishing with trolling lines: (for example, a sport fisherman's rod and reel with the line towed astern), which do not restrict maneuverability.
Other rules: Rule-26 prescribes the lights and shapes and Rule-18 prescribes the privilege and obligations for vessels engaged in fishing
(e) The word ‘seaplane’ includes any aircraft designed to maneuver on the water.
When on the water a seaplane is a vessel. Rule 31 gives the navigation light and shape requirements for seaplanes. Non-displacement crafts are not to be considered as seaplanes for the purpose of Rule 18(e).
(f) The term ‘vessel not under command’ means a vessel which through some exceptional circumstance is unable to maneuver as required by these Rules and is therefore unable to keep out of the way of another vessel. Examples:
Vessel with anchor down but not holding Vessel riding on anchor chains
Vessel with inoperative steering gear Sailing vessel becalmed
Exceptionally bad weather (relative to vessel claiming status)
Rule 18 assigns the privileges and obligations & Rule 27 prescribes the lights and shapes for not-under-command vessels. A NUC vessel is entitled to get privileges only when she displays required lights and shapes.
(g) The term ‘vessel restricted in her ability to maneuver’ means a vessel which from the nature of her work is restricted in her ability to maneuver as required by these Rules and is therefore unable to keep out of the way of another vessel. The term ‘vessel restricted in her ability to maneuver’ shall include but not be limited to:
Because of the nature of her work: The status does not apply to vessels that cannot maneuver because of external reasons such as - they are in a narrow channel or in shallow water or because of strong currents or bad weather. Vessels restricted in ability to maneuver may or may not be underway. These vessels are often called as RAM vessels.
Distinction: The vessels mentioned below (i - vi) must be engaged in their special operations to be entitled to the status as a vessel restricted in her ability to maneuver.
(i) a vessel engaged in laying, servicing or picking up a navigation mark, submarine cable or pipeline;
No Explanation written
a vessel engaged in dredging, surveying or underwater operations; No Explanation written
a vessel engaged in replenishment or transferring persons, provisions or cargo while underway;
No Explanation written
(iv) a vessel engaged in the launching or recovery of aircraft; No Explanation written
a vessel engaged in mine clearance operations; No Explanation written a vessel engaged in a towing operation such as severely restricts the towing vessel and her tow in their ability to deviate from their course.
Severely restricts: A vessel engaged in a routine towing operation is not normally justified as restricted-in-ability-to-maneuver status. This is emphasized in the definition by the words "severely restricts."
(h) The term ‘vessel constrained by her draught’ means a power-driven vessel which because of her draught in relation to the available depth and width of navigable water is severely restricted in her ability to deviate from the course she is following.
CBD Vessels: These vessels are specified to be only power-driven vessels. CBD vessels don’t necessarily mean VLCCs, ULCCs, Larger ships, Deep Draft Vessels. Even a small power driven vessel can be entitled to be a CBD vessel when her draft in relation to available depth and width of surrounding
navigable waters makes her restricted to deviate from her present course. Available depth & width of navigable water: The depth of water directly underneath the vessel is not the determining factor; rather, the depth close to either side of the vessel determines the level of constraint.
(i) The word ‘underway’ means that a vessel is not at anchor, or made fast to the shore, or aground.
Underway: Apart from the definition above, a vessel that is "underway" need not be moving through the water.
Making way through the water (used in Rules 26, 27, and 35): If a vessel underway is moving relative to the water, it is making way. For example, if a ship is headed up a river, making five knots through the water, and there is a five-knot current against it, then it is making way through the water even though it is making no progress relative to the shore.
Making no way through the water (used in Rule 35): If a vessel is making no way through the water, it is stopped and drifting. A vessel is drifting down the river is not making way, even though it is moving much faster over the bottom
At Anchor: Usually a vessel is considered at anchor only when she is holding the chain and brought up. A vessel is considered underway when she is dragging her anchor or if she is not yet brought up to anchor she has let go. (j)The words ‘length’ and ‘breadth’ of a vessel mean her length overall and greatest breadth.
Length: Here in this rule, Length means LOA but not LBP or Waterline Length. LOA: The maximum length of a vessel 's hull measured parallel to the
waterline, usually measured on the hull alone, and including overhanging ends that extend beyond the main bow and main stern perpendicular members.
LBP: Measured from the point the stem intersects the design waterline and the centerline of the rudderpost
Waterline Length: Measure between points where stem and stern enter the water.
Breadth: The greatest breadth does not always occur amidships.
(k) Vessels shall be deemed to be in sight of one another only when one can be observed visually from the other.
These eight rules do not apply to two vessels not "in sight of one another." Even though the vessels may know each other's exact course, speed, and position by means of Automatic Identification System (AIS) or Automated
Radar Plotting Aids (ARPA) or other devices, Rules 11 through 18 apply only if visual contact is also made.
(l)The term ‘restricted visibility’ means any condition in which visibility is restricted by fog, mist, falling snow, heavy rainstorms, sandstorms or any other similar causes.
Connections: Rules 19 and 35 apply only to vessels in or near an area of restricted visibility.
Other similar causes: Such as smoke from own vessel, other vessels, or ashore, and dust storms, smog (a kind of air pollution, originally named for the mixture of smoke and fog in the air) etc.
(m) The term ‘wing-in-ground (WIG) craft’ means a multimodal craft which, in its main operational mode, flies in close proximity to the surface by utilizing surface-effect action.
WIG crafts are not to be considered as seaplanes or non-displacement craft. The definition for "Wing-In-Ground" craft was added to address hybrid
water/air craft that can operate on the water and just above the water in ground effect -- on a cushion of air.
Part B - Steering and Sailing Rules
Section I - Conduct of Vessels in any Condition of Visibility
Rule-4: Application
Rules in this section apply to any condition of visibility.
Rule 4 tells us that vessels operating under any and all conditions of visibility are required to follow Rules 5 through 10. In other words, these Rules apply all of the time.
Rule-5: Look-out
Every vessel shall at all times maintain a proper look-out by sight and hearing as well as by all available means appropriate in the prevailing
circumstances and conditions so as to make a full appraisal of the situation and of the risk of collision.
STCW’95: Mandatory standards regarding watch keeping, including standards for keeping a proper look-out, are contained in Part A, Chapter VIII of the STCW Code.
Lookout: The term, as used by the Rules, denotes not a person but rather the systematic collection of information. Responsibility for maintaining a proper lookout lies with the vessel's
operator, not with a subordinate designated as "lookout." The vessel's operator--that is, Master, Watch Officer, or Person in Charge--is the lookout manager.
Sometimes, it’s stressed that a lookout man should be stationed forward if weather is good in order to ensure no-destructions to him. But this is also true that a lookout man stationed forward may not perform his duties properly due to lack of diligence.
Purpose of Lookout: The purpose of the lookout is to collect the information needed to avoid collisions.
Duty of the Lookout: Traditionally, the duty of the lookout was to watch out for vessels, lights, and other objects (such as reefs, shoals, and icebergs) by sight and hearing alone and to report their presence to the vessel's operator promptly. The lookout was allowed some discretion on what to report in crowded waters and would be assigned no other duties that would interfere with this important function.
Today, a proper lookout is a team effort. It is the Master's duty to ensure that a proper lookout is maintained at all times. That duty cannot be delegated. When a lookout man is stationed forward, he must use his discretion and report the lights or objects which are likely to bring risk of collision, especially small craft which may not have been observed from the bridge.
Interference on Sight & Hearing: Good eyesight is affected by environmental factors such as ambient light, weather conditions, water spray, or wind. Fatigue can also affect vision, as can moving between extremes of light. Similarly, hearing may also be impaired. The noise of wind and wave and ship's machinery may mask the sound you want to hear. The blast from a ship's own whistle blocks out other noises and will temporarily, perhaps permanently, reduce the hearing of the lookout. Hearing testing would be advised.
All Times: The duty to keep a proper look-out applies also when a vessel is at anchor, especially if there is a strong tide running, or if other vessels are likely to be passing by.
Proper and appropriate: These are vague terms. This rule doesn’t provide a precise guidance on adequacy of the lookout. However, STCW Code gives us a detailed guideline on determining the strength of lookout.
collision, without any allowance for good luck, in the prevailing circumstances and conditions
By Sight & Hearing and all available means: Sight, hearing, and "all available means" are tools of the lookout. Some of the available means are Binoculars, Radar (including long range scanning), VHF, Bridge-to-Bridge radiotelephone, Automated radar plotting aids, Differential GPS (DGPS), Satellite Navigation Equipment, Automatic Identification Systems (AIS), radio transponders, Vessel traffic services, Navigation and piloting instruments, sound receivers to receive fog signals etc.
Prevailing Circumstances & Conditions: Some examples
are:-A lookout in the open ocean can be less intense than one in coastal or inland waters. It cannot, however, be abandoned—mid-ocean collisions do occur. A lookout on a vessel at anchor is required, with the level of effort depending upon the location of the anchorage, depth of water, type of ground tackle, wind, currents, waves, and so forth. The lookout should determine whether the anchor is dragging and should warn other
vessels of the anchored vessel's presence.
The means and methods for maintaining a lookout vary with night and day. At night, lookouts should make greater use of binoculars and radar. Masters should post observers away from the vessel's own lights so as not to impair the night vision of the lookout. During the day and in good visibility, a vessel can be seen at a much greater distance, as indicated by the fact that a masthead light for the largest vessel need be visible for only six miles and for the smallest vessel, only two miles. During daylight, and under the most favorable conditions, the watch officer on a large vessel may perform the lookout alone.
The size and arrangement of a vessel have a direct bearing on the efforts required to maintain a proper lookout. On small vessels where there is an unobstructed all-around view and where there is no impairment of night vision, the craft's operator may both steer and keep the lookout.
Unobstructed view, simple controls, no distractions, and high maneuverability are important here.
Visibility is generally the key factor in maintaining a proper lookout. As the visibility decreases, the level of effort to maintain a proper lookout increases tremendously. Sight needs to be augmented by hearing, radar, and
radiotelephone. Unless you are in the open ocean, you should seek precise navigational information. In the case of low-lying fog, at least one person should be positioned high enough to see over the fog.
in mind when managing the lookout. If there is not enough information to assess the situation, you should tap all your resources to gather more. If you are still unable to acquire the information you need, then you should take steps immediately to reduce your requirement for information--for
example, by slowing or stopping. Otherwise, you are violating Rule 5. This is not one of those circumstances where doing more with less is a virtue. A lookout man should be always aware of what is happening on his own vessel keeping a check that all navigational equipment required for keeping the vessel on course are functioning correctly.
Rule-6: Safe Speed
Every vessel shall at all times proceed at a safe speed so that she can take proper and effective action to avoid collision and be stopped within a
distance appropriate to the prevailing circumstances and conditions. In determining a safe speed the following factors shall be among those taken into account:
Safe Speed: The word ‘safe’ is intended to be used in a relative sense. A speed could reasonably be considered safe in the particular circumstances. Every vessel shall at all times: This rule applies in all conditions of visibility to all vessels. The Officer of the watch should not hesitate to use the engines in case of need. However, timely notice of intended variations of engine speed should be given when possible.
Proper and effective action: The first objective of maintaining a safe speed is to permit the vessel "to take proper and effective action to avoid collision”. To be able to maneuver as prescribed by the Rules, the vessel must be moving slowly enough to control its forward motion. In some cases, it must also be moving fast enough for the rudder to effect a turn promptly.
To avoid hydrodynamic effects in shallow waters, vessel operators are expected to be familiar with these effects and to reduce their speed sufficiently to maintain positive rudder control.
Stopping Distance: The second objective of requiring a safe speed is to enable the vessel to be stopped "within a distance appropriate to the prevailing circumstances and conditions”. In most cases where the risk of collision exists, a course change will be the most common action. However, if maneuvering room is limited or if visibility is poor, stopping the vessel
(perhaps in conjunction with a turn) could be the best way to avoid or minimize damage.
Other rules: Rule 8 requires vessels to slow or stop to avoid collision or to give more time to assess the situation. Rule 19 requires that vessels in areas of restricted visibility encountering vessels forward slow to the bare
Factors to consider: Most of Rule 6 presents factors that must be considered in determining safe speed. These factors are not necessarily listed in order of importance, and the list is not exhaustive.
(a) By all vessels:
The state of visibility; Note: Refer Rule-19.
The traffic density including concentrations of fishing vessels or any other vessels;
Note: Traffic density is important because the probability of a collision increases with the density
(iii) The maneuverability of the vessel with special reference to stopping distance and turning ability in the prevailing conditions;
Note: Stopping distances will vary substantially depending on whether the vessel is turning or proceeding in a straight line. The maneuvering
characteristics of most of the larger vessels are required to be posted on the bridge. Operators should learn the characteristics before the information is needed. The distance that a vessel will cover in a crash stop before being brought to rest from full speed is likely to be between 5 and 15 ship lengths, depending upon speed, displacement, type of machinery, maneuverability of the vessel, Type of engines (steam, diesel, turbine, etc), Power of the engine, Stopping distance, Turning circle, Fast or slow vessel, Maneuverability with regard to Condition of loading, Draught, Trim, Etc.
(iv) At night, the presence of background light such as from shore lights or from back scatter of her own lights;
Note: Background lights and backscatter decrease the effectiveness of a lookout by sight and therefore require a proportional decrease in speed. A small vessel has a particular problem because the vessel's own lights are close to the operator. Careful design of the navigation light arrangement will minimize backscatter and reflection from the vessel itself.
The state of wind, sea and current, and the proximity of navigational
hazards; Note: The need to reduce speed in the face of mounting adversity The draft in relation to the available depth of water.
Note: Draft restrictions relate to speed in several ways. If there is little under keel clearance, it is likely that shallower water is nearby. It is easier to avoid running aground from a low speed, and if a grounding cannot be avoided, the damage will be less.
If a vessel's draft exceeds the depth outside a channel, the vessel will be limited to straight-line stopping within the channel, which is less effective than a combination of slowing or reversing engines and turning away. Hence a lower speed is usually required.
In shallower waters, a vessel's speed introduces hydrodynamic forces that are not present in deeper waters. The effect on the vessel is called "squat," and it increases as the underkeel clearance decreases and as the vessel's speed increases. The hydrodynamic effect of high speed through a channel may cause a vessel to be pulled toward or into the bank or may pull two vessels passing close together off course.
(b) Additionally, by vessels with operational radar:
Note: The term ‘operational radar’ means radar in use. In open waters a ship using radar may proceed at a relatively higher speed, provided the speed is adjusted appropriately upon detection of another vessel. Radar equipment varies greatly in power, sophistication, antenna installation, and so forth. The mariners need to understand these qualities and limitations thoroughly.
(i) The characteristics, efficiency and limitations of the radar equipment; Characteristics: Radar may fail to detect small targets, alterations of course made by other vessels are usually less apparent and the use of radar
bearings is more likely to result in a faulty appreciation of risk of collision than visual bearings taken by compass.
Efficiency: The efficiency of the equipment for the purpose of detecting the presence of other vessels and determining whether risk of collision exists must also be related to the competence of those observing it and the way it is being used. Range performance, Minimum range, Diameter of PPI, Scale of display, Plotting facilities, Range accuracy, Heading indicator, Bearing
accuracy, Azimuth stabilization.
Limitations: Because of their lower power and higher pulse repetition rate, these navigation radars--also called three centimeter (3 cm), X-band, and high frequency radars--have a limited range.
A vessel's course might be changed regularly to ensure that any vessel in a blind arc, which may be caused by a vessel's masts or other structures, could
be detected early.
Short range scales give good resolution and enable the detection of small targets; long range scales sacrifice detail to gain early detection. To the extent that different range scales are not available, speed should be reduced.
Constraints may be imposed by every range scale that can be used. When using the longer range scales definition and discrimination are reduced and small targets are less likely to be detected, whereas shorter range scales do not permit early detection of targets and do not enable the observer to obtain an overall assessment when several vessels are in the vicinity. The range scale which is most suitable for the locality should be selected but the scale should be changed at regular intervals. The scale should not be
changed when there is a dangerous target at close range. When two radar displays are available and in use it may be advantageous to select a different range scale on each display to avoid the necessity of switching scales.
(iii) The effect on radar detection of the sea state, weather and other sources of interference;
Vessel’s speed should be reduced when interference (caused by large waves, heavy rain or snow, or the like) impairs the performance of the radar.
Interference: The effect of rain clutter is much less when using l0 cm wavelength than when using 3 cm. This is often also the case with clutter caused by sea return. Vessels fitted with two radars, one of each wavelength, would be expected to make use of the 10 cm wavelength for detecting other vessels in conditions likely to cause severe clutter, particularly in heavy tropical rain squalls.
(iv) The possibility that small vessels, ice and other floating objects may not be detected by radar at an adequate range;
The location of the vessel and the season of the year are important in judging whether undetected vessels or ice may be present.
(v) The number, location and movement of vessels detected by radar; Accurate radar plotting becomes more difficult as the number of vessels increases. Automated radar plotting aids make the task easier. The greater the number of targets indicated on the radar display the more difficult it may be to determine risk of collision and to assess the effect of possible
maneuvers, although some radar systems are capable of providing information of this kind.
radar is used to determine the range of vessels or other objects in the vicinity.
The observed radar range of a vessel can be correlated to visibility by noting when the vessel can first be sighted. At night, when the vessel's lights can first be seen, the radar range of the vessel equates the visibility (assuming that the visibility is not so good that masthead light intensity becomes the controlling factor.
When fog or mist is considered likely to develop, the radar should be in operation. It may be possible to determine the extent of the visibility by observing the radar ranges at which other vessels or navigation marks are first visually sighted, or at which they disappear from view. At night the probable presence of fog may be indicated by failure to see the lights of a vessel which gives a strong echo within the normal visual range.
Rule-7: Risk of Collision
(a) Every vessel shall use all available means appropriate to the prevailing circumstances and conditions to determine if risk of collision exists. If there is any doubt such risk shall be deemed to exist.
The existence of risk of collision is implicit to the operation of other rules such as Rule 13 (Overtaking), Rule 16 (Action by Give-way Vessel), Rule 17 (Action by Stand-in Vessel), and Rule 18 (Responsibilities between Vessels). Risk of collision in Head-on situation: The relative bearings of two vessels affect the degree of risk. Two vessels meeting on near-reciprocal courses would close relatively rapidly, because their closing speed would be the sum of the two speeds. The risk of collision would arise while they were still
relatively far apart.
Risk of collision in Overtaking situation: Where one vessel is overtaking another on nearly the same course, the closing speed would be the difference between the individual speeds. Unless one is traveling a great deal faster than the other, it would take a long time for the overtaking vessel to draw abeam of the other. In the overtaking situation, the vessels would be relatively close together before risk of collision arose.
Risk of collision in Crossing situation: Crossing situations would be somewhere between meeting and overtaking.
Avoid Development of Risk of Collision: Either vessel is, of course, free to act before risk of collision exists in order to avoid it altogether. If RoC with
another vessel doesn’t exist, then there is no necessity to take action as a give way vessel.
complete, then risk of collision shall be deemed to exist. In case of doubt, the OOW must call Master immediately as per STCW Code, Ch-VIII. It’s
confusion about a situation and feels whether he should call Master or not. Beyond this point, the OOW’s delay in calling Master could be considered as negligence and at times, calling
Master late might result in a critical situation when Master may not have many options on hand to avoid a close quarter’s situation or collision. All available means: Examples are
-Look out
Compass repeaters Binoculars
Sound / light signaling equipment Radars / ARPAs
The radiotelephone may be used to advantage in certain circumstances for the purpose of clarifying a situation involving two vessels and indicating intentions via well regulated VTIS. However, collision avoiding actions shall not be taken basis VHF agreement between two vessels since it’s never guaranteed that the second vessel is the vessel that you’re trying to
communicate with as many vessels make funs out of it. Valuable time may be wasted in attempting to make radio contact instead of concentrating on the assessment of collision risk and the need for action. Reference is also made to the further danger of proposing, by VHF radio, to take action which is not in compliance with the Collision Regulations. In RoR, there is no
mention about the use of RT to determine RoC, rather appropriate sound signals are prescribed for the same.
As AIS can be used to advantage for collision avoidance, such as in
determining the identity of another vessel and in more rapid detection of changes of heading, vessels may be expected to make use of the equipment in appropriate circumstances. The AIS target data (CPA, TCPA etc.) MUST not be taken as correct as it is found accurately only in ARPA/Radars. An OOW should acquire the targets on Radar/ARPA using Radar functions instead of just simply clicking the AIS Symbol of a target echo on radar screen to get CPA, TCPA, etc.
to determine risk of collision depends on the prevailing circumstances and conditions, such as daytime or night time, low traffic or heavy traffic, coastal waters or ocean waters, clear visibility or restricted visibility, etc.
(b) Proper use shall be made of radar equipment if fitted and operational, including long-range scanning to obtain early warning of risk of collision and radar plotting or equivalent systematic observation of detected objects. Proper use of Radar Equipment: Rules 6, 7, 8 and 19 contain specific
references to the use of radar and there is an important implied reference in Rule 5. Proper use of radar may include optimum setting of all controls, appropriate range scale & display, etc.
The value of radar in assessing risk of collision in poor visibility is obvious. Rule 19 (Conduct of Vessels in Restricted Visibility) requires that a vessel in restricted visibility determine whether risk of collision exists when it detects by radar alone the presence of another vessel. But radar is also valuable in clear weather after a target has been sighted visually, being better able than the human eye to measure range and other distances.
Long range scanning: In any kind of weather, long range scanning is a very useful tool to an OOW. If a target is detected at long range, an OOW can do little alteration of course / speed to avoid a RoC. However, RoC in a head-on situation remains the same even at long range. If two high-speed vessels meet head-on, their relative speed becomes very high and TCPA reduces significantly, therefore an OOW gets less time to takes actions. But if the situation is detected at long range, the OOW gets sufficient time to take early action. That’s why the OOW should cultivate a habit of doing long range scanning of targets frequently in his/her watch.
True Motion Display: The OOW must select the radar display better suited to the operating conditions. In general, true-motion (sea- or ground-stabilized) radars are preferred for navigation and piloting in confined waters as the position of the observer’s own ship moves in accordance with its own path. An alteration of course made by another vessel moving at fairly high speed is likely to be more readily apparent on the true motion display from the
change in direction of the echo trail. True motion is generally more suitable for use with the lower range scales in congested waters rather than in the open sea.
Relative Motion Display: Relative-motion displays allow the observer to assess more quickly the movement of other vessels in relation to his or her own movement.
All but the smallest vessels are required to have radars stabilized in azimuth (that is, in the horizontal plane). Radars without compass stabilization are almost useless for determining the actions of other vessels.
True & Relative Radar Plotting: The principles of relative plotting should be understood by all observers, as this is the method which enables the closest position of approach to be determined.
The true plot is simpler to understand, and is considered by many to be superior when there are several targets on the screen. Alterations of course, or speed, by the observed vessel, carried out simultaneously with, or shortly after, an alteration by own vessel, are likely to be more readily detected by a true plot than by a relative plot.
Use of Vectors: The use of vector is very common. You can use this function for multiple targets on the radar screen. Usually, the user selects relative vector to see how a target will pass her own ship actually. Alteration of course and speed, however, don’t get updated in vector immediately, it takes sometimes. A prudent user sometimes changes the vector setting from relative to true to see a target’s actual course and thus it helps to find
target’s aspect. The use of appropriate vector length is also very important. Longer vector-length of numerous targets on the radar screen lead to an unnecessary clutter and confusion to the OOW.
Equivalent Systematic Observations: Plotting is not required if "equivalent systematic observation" is used. These other observation techniques include manual and automatic (computerized) radar plotting aids or the listing of bearing, range, and time at regular intervals. Plotting by the vessel's operator in congested waters may take so much time that it becomes counterproductive. In such cases automated radar plotting aids are especially appropriate.
(c) Assumptions shall not be made on the basis of scanty information, especially scanty radar information.
Assumption & Scanty Information: The word ‘Scanty’ stands for ‘Insufficient’. Assumptions made on the basis of scanty information have been a
contributory cause of many collisions in both clear and restricted visibility. Rule 7 warns mariners against relying on radar for more information than it can realistically give. The mariner who assumes an approaching vessel will pass well clear after making a couple of long-range radar observation is inviting danger and violating Rule 7.
Distances magnify small errors, and errors are almost inevitable because of the imprecision of observations made from a moving vessel. Nor can you
assume that the other vessel is maintaining a constant course and speed. Regular and consistent checking of observations is imperative.
Several observations should be taken at short and regular intervals to reduce the effects of these random errors when there is a possibility of a close
quarter’s situation developing. Bearings taken relative to the ship’s structure can be very misleading in determining whether risk of collision exists.
(d) In determining if risk of collision exists the following considerations shall be among those taken into account:
(i) Such risk shall be deemed to exist if the compass bearing of an approaching vessel does not appreciably change;
The closest distance of approach is perhaps the prime element in the risk of collision situation. A collision occurs when the distance of closest approach goes to zero. Sighting an approaching vessel against components of the ship's structure may give a rough indication of whether there is risk of collision and may provide sufficient basis for deciding whether to make a bold alteration to pass astern of a vessel being overtaken or crossing from the starboard side.
A number of factors are involved in such an assessment: Closest distance of approach
Type of waterway - The type of waterway plays a part in the calculation of risk. On the open ocean the distance of closest approach triggering risk of collision is greater than in confined waters because on the ocean it is easier to keep well clear.
Vessel size and maneuverability - Vessel size and maneuverability have a substantial impact on risk of collision. A small vessel that can stop or turn in its own length has a much smaller zone of risk than a large vessel that may need a mile or more to stop and only begins to turn after the rudder is put over.
Speed - Speed expands the zone in which risk of collision exists. Higher speeds give the mariner less time to refine the accuracy of vessel path predictions (remember Rule 6).
Distance out from closest point of approach Relative bearings
Appreciably change of bearing: Here bearing means true bearing but not relative bearing. Due to appreciable change of bearing, the change in target data and aspects will become evident, such as a noticeable change in CPA,
TCPA, BCR, etc. However, an appreciable change of bearing at greater ranges does not necessarily mean that there is no risk of collision. The other vessel may be making a series of small alterations which have not been observed.
(ii) Such risk may sometimes exist even when an appreciable bearing change is evident, particularly when approaching a very large vessel or a tow or when approaching a vessel at close range.
Large vessel or tow: Even if the compass bearings between two vessels do change, there may still be the potential for collision. A tow has two
components – the towing vessel and the vessel being towed. If a RoC doesn’t exist with the towing vessel, it may exist with her tow. The same explanation goes for a large vessel – bearings between bow and stern differ significantly. Mariners must consider the length of an approaching vessel before
determining that a RoC doesn’t exist with the other vessel’s bow and stern or with the towed vessel and her tow.
Risk associated with changing bearing at close range: An appreciable change of bearing at close ranges does not necessarily mean that there is no risk of collision. An appreciable change of bearing at short range may be associated with a dangerously close passing distance. The rate of change of bearing increases as two vessels pass too close to each other. Such a passing distance will bring danger of collision.
If an overtaking vessel with greater speed, approaching from starboard quarter of a vessel being overtaken with lower speed, suddenly starts
crossing the bow of the vessel being overtaken assuming that the overtaking vessel can execute this action safely, a collision may happen if overtaking vessel’s steering or M/E fails at that point due to the fact that both vessels are at close range. Also, at close range in confined waters, the effect of interaction between two vessels is significant and a collision is always possible.
Rule-8: Action to Avoid Collision
(a) Any action to avoid collision shall be taken in accordance with the rules of this Part and, if the circumstances of the case admit, be positive, made in ample time and with due regard to the observance of good seamanship. This rule tells how the avoiding action must be executed, not which vessels are required to take the avoiding action.
Shall, if the circumstances of the case admit: ‘Shall’ is a mandatory word. ‘Shall’ is used to emphasize the need for positive action to be taken in ample time. ‘If the circumstances of the case admit’ is an escape clause though.
Positive, made in ample time, with due regard to the observance of good seamanship: These are indefinite terms.
Positive: Positive action is a significant change in vessel’s course and/or speed. A large alteration of course or speed to avoid a collision indicates that the intention of the action is positive. A vessel’s positive action becomes easily evident to others observing her.
Ample Time: In this rule, action shall be taken in ample time means that an action shall be taken in a time so that a collision can be avoided. This
paragraph didn’t say action is to be taken in ample time to avoid a close quarter’s situation. If we compare ample time and good time, we can say that ample time is meant for avoiding a collision and good time is meant for avoiding a close quarter’s situation. So, as per RoR, good time occurs much earlier than ample time.
Good observance of Seamanship: Some examples of good seamanship have been mentioned in discussions for Rule-2. Do not take an action which makes the situation worse for any other ship in the vicinity; assess what they may have to do.
(b) Any alteration of course and/or speed to avoid collision shall, if the circumstances of the case admit, be large enough to be readily apparent to another vessel observing visually or by radar; a succession of small
alterations of course and/or speed should be avoided.
Let the other vessel know what you are doing. Make it obvious by sight in good visibility and obvious on the radar screen in areas of restricted visibility. Give the proper maneuvering signals if operating under the International Rules.
(c) If there is sufficient sea room, alteration of course alone may be the most effective action to avoid a close-quarters situation provided that it is made in good time, is substantial and does not result in another close-quarters
situation.
Alteration of Course Alone: Two variables can be altered to avoid collisions: Course and Speed. On larger vessels, change of speed may take a
considerably long time, especially when the engines are not ready for maneuvering but you need to change speed immediately. That’s why, this paragraph allows for a course change alone, which can be made directly and immediately from the bridge. Alterations of speed take longer to put into effect than alterations of course so they are less likely to be readily observed by other vessels
Close-quarters situations: There is no definition of Close-quarters situations. But generally we can suppose that it’s a situation between two vessels when action taken by one vessel may not be sufficient to avoid the collision. In rivers, harbors, and other inland waterways; close-quarters situations are unavoidable. The term close-quarters situation has been implied in Rule7(CPA distance which helps assess a risk of collision), Rule8d (safe distance -the minimum
passing distance permitted by the Rules) and Rule-16 (well clear - the minimum passing distance permitted by the Rules). Both terms ‘Safe
Distance’ in Rule-8(d) and ‘Well Clear’ in Rule 16 represent a greater distance than ‘close-quarters’.
In a close-quarters situation, decisions might have to be taken without time for proper thought.
Good time: Good time means ‘early’. There is no specific time at which good time begins. It’ll depend on a particular situation. Maneuvers taken to avoid a close-quarters situation should be taken at a time when the responsible officer does not have to make a quick decision or a decision based on inadequate information. We can say that if a vessel fails to take action in good time, she may find herself in a close-quarters situation. This paragraph didn’t say action is to be taken in good time to avoid a collision.
Substantial: Alterations of course alone should be substantial so that they may be readily apparent to another vessel. In restricted visibility, alterations of course and speed should be substantial so that they may be readily
apparent to another vessel observing visually or by radar. While taking an action to void a close quarter’s situation with one vessel, the OOW must monitor her action properly so that the action doesn’t result in another close quarter’s situation.
(d) Action taken to avoid collision with another vessel shall be such as to result in passing at a safe distance. The effectiveness of the action shall be carefully checked until the other vessel is finally past and clear.
Safe Distance: What distance is safe depends on the circumstances; suffice it to say that if you are obligated to take the action, the person on the other vessel should not feel compelled to act also to increase the distance still further.
Effectiveness of the Action: If action to avoid collision is required, the mariner must take effective and readily apparent action, whether it be a course
change or a speed change or a combination of the two. A course change works better for meeting situations, whereas for vessels crossing at near-right angles, a speed change (perhaps in combination with a course change) often works better. Continuing change of compass bearing would be one indication of the initial effectiveness of the avoiding action. However, an appreciable change of bearing may not be sufficient to establish that the vessels will eventually pass clear of one another. Subsequent action by the other vessel could result in renewed risk of collision.
(e) If necessary to avoid collision or allow more time to assess the situation, a vessel shall slacken her speed or take all way off by stopping or reversing her means of propulsion.
When a vessel is obliged to take action to avoid collision with another vessel which is crossing, or which she is overtaking, she may be prevented from making course alterations due to lack of sea room or to the presence of other vessels; in such circumstances it will be necessary to slacken speed or take all way off. In restricted visibility when a close quarters situation cannot be avoided with a vessel forward of the beam, or a fog signal is heard forward of the beam, it will usually be necessary to reduce speed or stop the ship. The speed must also be reduced if it is necessary to allow more time to assess the situation (As per Rule-5, a full appraisal of situation is required)
Taking all way off or reversing propulsion: You should refer to ship’s
maneuvering booklet to know about her maneuvering characteristics. An OOW should have thorough knowledge about the turning circle of the vessel. It’s a good practice that the bridge team is briefed about the limitations of M/E and the procedures of stopping M/E in case of an emergency. Stoppage time (Sea ahead to zero speed) depends on various factors, such as size of the vessel, present displacement, depth of water, wind, sea conditions, current, etc. Usually the maximum astern power is 60-80% of maximum ahead power.
Helm Action in stopping the vessel: Helm action taken in the initial stage of a crash stop, when still moving at high speed, will result in a considerable increase of resistance and reduce the stopping distance. A method which may be used in some circumstances is to put the helm hard over one way then hard over to the other side with the engines on dead slow ahead, then to put the engines full astern. This should reduce the period of applying astern power so that the vessel is less likely to be slewed in the final stage. Crash Stop: To avoid an imminent danger like collision, grounding etc, it becomes necessary to stop the vessel as soon as possible. Crash
maneuvering is turning the engine in opposite direction to reduce the ahead speed of the ship. After certain time, the ship stops and starts steaming in astern direction. The procedures of crash stop are as below (it may vary from ship to ship):
The bridge informs about the emergency situation and requests E/R for crash stop
The Fuel Lever (Starting Lever) is set to Stop Position and the helm is put hard-over to either port or starboard so that speed drops faster. After the stoppage, she may come off the original course line by large amount. For
right handed propelled ship, the bow will cant to starboard.
Avoid attempting Emergency Stop of M/E since it takes some times to reset parameters of M/E before a restart is possible
After putting the Fuel Lever to stop position, observe the M/E rpm indicator. The rpm will still be showing for few minutes since the propeller doesn’t stop instantly even after the Fuel Lever is set to Stop Position. At that point,
engineers will give stern movement by air only (often called as brake air), i.e. no fuel will be used. This movement is given for a very short period to stop the movement of the crankshaft or the propeller. Ship’s speed (by
momentum) will be dropping slowly and few minutes after stop command is given, the rpm will show Zero.
When the rpm rests to zero, order full astern directly regardless of whatever speed the vessel might be proceeding with at that moment
Finally, the vessel will start to get stern-speed slowly.
Damage to Engines: In this type of maneuvering, the main engine is
subjected to severe stress and load. To avoid the damage to M/E through a crash stop maneuver and provided that time permits to avoid the danger, it is suggested that a quicker and safer way to stop a vessel would be to stop the engines instantly then, after a delay of three minutes or so, to give slow astern, half astern and full astern, thus avoiding acute cavitations. More recent evidence from ship trials and model tests seems to indicate that many vessels, especially those fitted with diesel engines, could best be stopped by giving ‘full astern’ as soon as possible, but it can generally be said that even if the engines can be made to go astern within one minute of the order ‘stop’ the retarding effect would be small and the risk of damage to the machinery would be great. The above remarks apply to a vessel moving at high speed. The engines can be more readily reversed when the speed is low. For the interest of safety, OOW or Master must not hesitate to do a crash stop. (f)
(i) A vessel which, by any of these rules, is required not to impede the passage or safe passage of another vessel shall, when required by the circumstances of the case, take early action to allow sufficient sea room for the safe passage of the other vessel.
Not to impede to avoid development of RoC: Vessels directed "not to
impede" other vessels should take early action to keep clear by wide margins so that a RoC doesn’t develop. The other vessel shouldn't become concerned enough to alter its course or speed, or otherwise feel obligated to act
differently from the way it would if the would-be impeding vessel weren't there.
Examples: Rule-9(b, c, d) & 10(i) mention about not to impede passage of a vessel, Rule-10(j) mentions about not to impede the safe passage of a power
driven & 18(d)(i) mentions about not to impede passage of a vessel constrained by her draught.
(ii) A vessel required not to impede the passage or safe passage of another vessel is not relieved of this obligation if approaching the other vessel so as to involve risk of collision and shall, when taking action, have full regard to the action which may be required by the rules of this Part.
What if RoC exists: The vessel that had been originally directed to not
impede the other should retain that burden even after risk of collision arose. That does not mean, however, that the (usually larger) vessel that was not to be impeded continues to have the right of way. If the not-to-be-impeded vessel would be the give-way vessel under the general rules, it has the duty to stay out of the way of the impeding vessel after risk of collision arises because of the application of Rule 17(a)(i). Early action in compliance with Rule 8(f) is compatible with Rule 17(a)(ii), which permits action by the stand-on vessel. The impeding vessel also cstand-ontinues to have a duty to stay out of the way after risk of collision arises, and does not gain the stand-on status that the general rules might have given it. Both vessels would be obligated to stay out of the way and the impeding vessel would have a double duty to stay out of the way.
Example # 1: When a power-driven vessel and a sailing vessel are
approaching each other, the power-driven vessel is required by Rule 18(a) to keep out of the way when risk of collision begins to apply, although she may be proceeding along a narrow channel or traffic lane, but this does not
relieve the sailing vessel of the obligation to take early action to allow sufficient sea room.
Example # 2: If one of two power-driven vessels, crossing so as to involve risk of collision, is required not to impede the passage of the other vessel, she must, in compliance with Rule 8(f), take early action to allow sufficient sea room for the safe passage of the other vessel although the other vessel may be required by Rule 15 to keep out of the way.
Full regard to the action: A vessel taking action as per Rule 8(f)(ii) shall take into account the possibility of both vessels taking conflicting actions when there is risk of collision. However, as it is not possible to establish the precise distance apart at which risk of collision begins to apply, a vessel taking early action not to impede should also have full regard to the action which may be taken by the other vessel (as a give way vessel). Rules 14, 15 and 17(c) indicate the form of action to be taken.
(iii) A vessel the passage of which is not to be impeded remains fully obliged to comply with the rules of this part when the two vessels are approaching one another so as to involve risk of collision.
