Keeping a Navigational Watch

Prerequisites

You should have read the lesson on the OOW (Unlimited) certificate route, and you should already know the COLREGs at Yachtmaster level, basic radar and the idea of CPA and TCPA. Experience of night watches on a yacht or as a bridge rating helps a great deal: this lesson takes what you did as a lookout or helmsman and shows what the officer in charge is responsible for.

Learning Objectives

By the end of this lesson you will be able to:

Explain where the rules on watchkeeping come from: STCW Chapter VIII, Section A-VIII/2 of the STCW Code, and the MCA's MGN 315.
Describe the duties of the officer of the watch (OOW), and why the OOW remains responsible when the master or a pilot is on the bridge.
Organise a proper lookout and decide when the OOW may be sole lookout.
Use the master's standing orders and night orders correctly.
Hand over and take over a watch, step by step.
List the situations in which you must call the master, and say what you do while you wait.
Apply the STCW hours of rest and the rules on fitness for duty, including alcohol limits.
Keep the deck log and other bridge records properly.

Where the Rules Come From

STCW Chapter VIII

The STCW Convention, Chapter VIII, deals with fitness for duty (Regulation VIII/1) and watchkeeping arrangements and principles (Regulation VIII/2). The detail is in the STCW Code:

Section A-VIII/1: hours of rest and the prevention of drug and alcohol abuse.
Section A-VIII/2: watchkeeping arrangements and principles to be observed. Part 2 covers voyage planning; Part 3 the general watchkeeping principles; Part 3-1 the principles for keeping a navigational watch, which is the heart of the OOW's job; Part 4-1 covers watchkeeping in port.

These are mandatory, and the UK applies them through the Merchant Shipping (STCW) Regulations 2022 and the hours of work regulations.

MGN 315

The MCA's MGN 315 (M), "Keeping a safe navigational watch on merchant vessels", explains how the MCA expects the STCW principles to be applied on UK ships. It points to the ICS Bridge Procedures Guide as the principal guide to good practice. MGN 315 is where the MCA states its strongest views: for example, that it is dangerous and irresponsible for the OOW to be the sole lookout in darkness or restricted visibility.

The company's Safety Management System

Under the ISM Code every company has a Safety Management System (SMS) with bridge procedures and checklists. The SMS turns STCW and MGN 315 into "how we do it on this ship". The master's standing orders sit on top of the SMS. When they disagree with a regulation, the regulation wins; when they are stricter, follow them.

The OOW's Responsibility

The OOW is the master's representative. STCW and MGN 315 put it plainly: the OOW is primarily responsible at all times for the safe navigation of the ship and for complying with the COLREGs.

That responsibility does not move just because someone senior walks onto the bridge:

The master on the bridge. You stay in charge of the watch until the master tells you specifically that they have taken the con, and that is mutually understood. The words matter: "I have the con" from the master, "The master has the con" from you, and a note in the log.
A pilot on board. The pilot advises and cons the ship, but the master and OOW remain responsible. The OOW must cooperate closely with the pilot, keep an accurate check on the ship's position and movements, and if in doubt about the pilot's actions, ask the pilot for clarification. If doubt remains, call the master and take whatever action is needed before the master arrives.
Engines and helm. The engines are at the OOW's disposal. Give the engine room notice when you can, but never hesitate to use the engines in an emergency. Know the stopping distances and turning circles from the wheelhouse poster before you need them.

The OOW's duties in a watch

STCW Code A-VIII/2 Part 3-1 and MGN 315 give the duties. In practical terms, during your watch you must:

Keep the watch on the bridge, and never leave it until properly relieved.
Keep a proper lookout (see below).
Fix the position at frequent intervals, by more than one method whenever possible, and check that the ship is following the planned track.
Check the gyro and magnetic compass errors at least once a watch when possible, and after any large alteration. Compare the gyro and magnetic compass headings regularly.
Check the steering: test manual steering at least once a watch when on autopilot, and change to hand steering in good time in traffic, restricted visibility and other hazardous situations.
Use the radar whenever restricted visibility is met or expected and at all times in congested waters, and make sure the range scales are changed often enough to detect contacts as early as possible.
Monitor the engine, steering, navigational equipment and alarms, and act on any alarm.
Record the bridge activities and events in the log.
Not take on other duties that interfere with safe navigation: chart corrections, paperwork, cargo calculations and the phone come second.

The Lookout

COLREG Rule 5 requires every vessel to maintain a proper lookout by sight and hearing and by all available means. STCW Code A-VIII/2 Part 3-1 says the lookout's job is to:

maintain continuous vigilance, by sight and hearing and by all other means, with regard to any significant change in the operating environment;
fully appraise the situation and the risk of collision, stranding and other dangers to navigation; and
detect ships or aircraft in distress, shipwrecked persons, wrecks, debris and other hazards.

The rules that follow from it:

The lookout must give full attention to the job and must not be given other duties that interfere.
The helmsman is not the lookout while steering, except in small ships where an unobstructed all-round view is available at the steering position and there is no impairment of night vision or other obstruction to keeping a proper lookout.
The OOW may be the sole lookout in daylight only, and only after the master has assessed the situation carefully and decided it is safe. MGN 315 lists what the master must consider: weather and visibility, traffic density, proximity of dangers to navigation, the attention needed near traffic separation schemes, the bridge layout and blind sectors, the radar fitted, and the distractions of GMDSS, administration and equipment checks. Assistance must be immediately available.
In darkness or restricted visibility, the MCA considers it dangerous and irresponsible for the OOW to be the sole lookout. Post a dedicated lookout.

Using all available means

"All available means" includes radar (both sets where fitted, on different ranges), ARPA or ATA tracking, AIS, ECDIS, VHF and sound. But AIS is not a lookout. Small craft, warships, many fishing vessels and floating hazards do not show on AIS, and AIS data can be wrong. ECDIS overlays can hide small radar echoes. Look out of the window first, then use the electronics to measure what you see.

Night vision

Full dark adaptation takes about 30 minutes, and a single glance at a bright screen or torch undoes much of it. Keep displays on night palettes and dimmed, use red light for the chart table, and keep the bridge dark. This is why a relief must arrive early at night.

Standing Orders and Night Orders

Master's standing orders

Standing orders are the master's permanent written instructions for the bridge. Every officer reads and signs them on joining, and again when they are changed. They typically cover:

The minimum CPA the master expects in open sea and in coastal waters (for example, 2 nm in open sea, 1 nm in coastal waters, with the OOW free to increase it).
When to call the master, often stricter than the STCW list.
Position fixing intervals for each kind of water.
Use of hand steering, engines and sound signals.
Lookout manning by day and by night.
Use of VHF for collision avoidance (usually: do not agree manoeuvres by VHF; follow the COLREGs).
Standing instructions on BNWAS, ECDIS alarms and safety settings.

Night orders

Night orders are written by the master each evening, in the night order book, for that night: expected traffic or landfall, the time to call the master, weather to watch for, any special instruction. Each OOW reads and signs them when taking over. If something in them is unclear, ask before the master turns in, not at 0300.

The standing orders and night orders never take away your duty to use your own judgement. If the night orders say "call me at the Ushant TSS" and the visibility closes in two hours earlier, you call the master two hours earlier.

Watch Arrangements

A typical deep-sea three-watch system:

Watch	Officer
0000 to 0400 and 1200 to 1600	Second officer
0400 to 0800 and 1600 to 2000	Chief officer (mate)
0800 to 1200 and 2000 to 2400	Third officer

The master decides the composition of the bridge watch, taking into account visibility, traffic, the use of navigation aids, whether automatic steering is in use, weather, unusual demands such as an approaching TSS, and the qualifications and experience of the people available. The watch must be enough to keep a proper lookout at all times.

Some ships, particularly with only two watchkeeping officers, use a six on, six off system. That makes it much harder to comply with the hours of rest, and fatigue on six-on six-off ships has featured in many accident investigations.

Handing Over and Taking Over

The handover is one of the riskiest moments of the watch. Information that one officer has carried in their head for four hours has to be transferred accurately, and the incoming officer's eyes and brain are not yet tuned in. The diagram shows the order of a good handover, and its two rules.

Ten steps for taking over a navigational watch, with when not to hand over and who holds responsibility until the words are said

What the relief must check

STCW Code A-VIII/2 Part 3-1 says the relieving officer must be satisfied about:

standing orders and other special instructions of the master relating to the navigation of the ship;
position, course, speed and draught;
prevailing and predicted tides, currents, weather, visibility and their effect on course and speed;
procedures for the use of main engines to manoeuvre when they are on bridge control;
the navigational situation, including the operational condition of navigational and safety equipment in use, errors of gyro and magnetic compasses, the presence and movement of ships in sight or known to be in the vicinity, conditions and hazards likely to be met during the watch, and the possible effects of heel, trim, water density and squat on underkeel clearance.

The two rules

Do not hand over during a manoeuvre. If a manoeuvre or other action to avoid a hazard is taking place when the relief arrives, the handover is deferred until the action is complete. The outgoing officer finishes it.
Do not hand over to someone unfit. If you have reason to believe the relief is not capable of carrying out the watch (tired, ill, under the influence of alcohol or drugs), you must not hand over. Call the master.

Night handover in practice

The relief arrives 10 to 15 minutes early, reads the night orders in red light, and spends a few minutes letting their eyes adapt before taking over.
The outgoing officer briefs target by target: "Two targets. Fishing vessel fine on the port bow, 4 miles, showing trawling lights, bearing drawing left, CPA 1.5 miles. Container ship astern, overtaking, will pass 1 mile to starboard in about 40 minutes."
The relief looks at each target by eye and on radar before accepting the watch.
The handover ends with clear words: "I have the watch," acknowledged by the outgoing officer, and logged.

Many companies use a handover checklist from the SMS, based on the ICS Bridge Procedures Guide. Use it, but do not let it become a box-ticking ritual: the purpose is a shared picture.

Calling the Master

STCW Code A-VIII/2 Part 3-1, paragraph 32, lists when the OOW must notify the master immediately. The diagram sets them out.

The ten situations in which the OOW must call the master immediately, under STCW Code A-VIII/2

In full, call the master:

if restricted visibility is encountered or expected;
if the traffic conditions or the movements of other ships are causing concern;
if difficulty is experienced in maintaining course;
on failure to sight land, a navigation mark or to obtain soundings by the expected time;
if, unexpectedly, land or a navigation mark is sighted or a change in soundings occurs;
on breakdown of the engines, propulsion machinery remote control, steering gear or any essential navigational equipment, alarm or indicator;
if the radio equipment malfunctions;
in heavy weather, if in any doubt about the possibility of weather damage;
if the ship meets any hazard to navigation, such as ice or a derelict; and
in any other emergency or if in any doubt.

Then the key sentence: despite the requirement to notify the master immediately, the OOW shall, in addition, not hesitate to take immediate action for the safety of the ship, where circumstances so require.

How to call

Make the call short and clear: who you are, where the ship is, what the problem is, what you have done and what you propose. For example: "Captain, second officer. Visibility has dropped to about one mile in rain, 12 miles south of the Lizard. I've posted a lookout, started fog signals, gone to hand steering and warned the engine room. Two targets on radar, nothing closer than 3 miles. Request you come to the bridge."

Then carry on running the watch until the master is on the bridge and has said that they have the con.

Why OOWs do not call

Investigations repeatedly find OOWs who saw the problem but did not call the master: they did not want to wake them, they thought they could handle it, or the master had made it clear that calls were unwelcome. A good master says, in the standing orders and in person, "If in doubt, call me. I would rather be called a hundred times for nothing than once too late." A good OOW calls anyway.

Fitness for Duty

Hours of rest

Fatigue is one of the most common factors in groundings and collisions. STCW Code A-VIII/1 sets minimum rest for every watchkeeper and anyone with safety, security or pollution prevention duties:

at least 10 hours of rest in any 24-hour period;
at least 77 hours of rest in any 7-day period;
rest may be divided into no more than two periods, one of which must be at least 6 hours; and
the interval between consecutive periods of rest must not exceed 14 hours.

Musters and drills must be conducted in a way that minimises disturbance of rest and does not induce fatigue. A seafarer on call (for example, for unmanned machinery space alarms) must get adequate compensatory rest if their rest is disturbed. The master may suspend the schedule in an emergency affecting the safety of the ship, persons on board or cargo, or to give assistance to others in distress, and must then make sure the people affected get adequate rest afterwards.

The ship must post a table of shipboard working arrangements, and each seafarer's daily hours of rest must be recorded and signed. In the UK the detailed law is in the Merchant Shipping hours of work regulations, which also implement the Maritime Labour Convention (check MSN 1868 for the current UK application).

The diagram shows why the total alone is not enough.

Two 24-hour timelines: a plain 0-4 watch with 16 hours of rest in two periods, and an arrival day with 13 hours of rest in four short periods, which breaches the rules

On the arrival day the second officer has 13 hours of rest, well over 10, but in four pieces, none longer than four hours. That breaks the "no more than two periods, one of at least 6 hours" rule. Worse, the officer will be on watch again at 0000 having had broken sleep all day: exactly the pattern that ends with an OOW asleep in the chair at 0330.

Falsifying rest hour records is common and dangerous. The records exist to show the master and the company when the manning is not enough for the work. If the records are made to look compliant, nobody can fix the real problem.

Alcohol and drugs

STCW requires a limit of not more than 0.05% blood alcohol (0.25 mg/l in breath) for masters, officers and other seafarers performing safety, security and marine environmental duties. In the UK, the Railways and Transport Safety Act 2003 makes it an offence for a professional mariner on duty to exceed 50 mg of alcohol in 100 ml of blood (or 25 micrograms in 100 ml of breath). Many companies have zero alcohol policies, which are stricter still. Prescription and over-the-counter medicines that cause drowsiness also make you unfit; tell the master.

BNWAS

SOLAS Chapter V requires a bridge navigational watch alarm system (BNWAS) on ships. If the OOW does not reset it within the dormant period (between 3 and 12 minutes), it sounds on the bridge, then in the cabins of the master and back-up officer, then more widely. The BNWAS must be on whenever the ship is under way. A BNWAS switched off, or reset automatically by a weight on a button, is a red flag for the whole bridge culture.

Bridge Records and the Log

The log is a legal record. It may be read by a court, the MAIB, Port State Control and the company's insurers. Write in it as if they will.

What goes in the deck log during a watch typically includes:

Positions at regular intervals and the method used (GPS, radar range and bearing, visual bearings, celestial).
Course steered and course made good; gyro and compass errors.
Weather: wind, sea, swell, visibility, pressure and its trend, at least once a watch.
Changes to steering mode (auto or hand), engine orders and speed changes.
When the master took or handed back the con; pilots embarked and disembarked.
Navigation in restricted visibility: start and end times, sound signals in use, precautions taken.
Any incident, alarm, equipment failure, near miss or unusual event.
Handover: "Watch handed over to 3/O" with time.

Good practice:

Never erase or blank out. Correct a mistake by drawing a single line through it, so it is still readable, and initial it.
Write it at the time, or as soon as safely possible. A neat log filled in at the end of the watch from memory is a weak document.
Electronic logs are increasingly used and are acceptable when approved; the same rules of accuracy apply.
Other bridge records include the GMDSS radio log, the compass error book, the chronometer or time error record, the night order book, and the record of hours of rest.

Remember too that the voyage data recorder (VDR) records radar, ECDIS, positions, VHF and bridge audio. What happened on the bridge will be known.

Worked Example: A Watch That Changes

You are the second officer on a 40,000 GT bulk carrier, heading 230° at 13 knots in the western approaches to the English Channel, taking the 0000 to 0400 watch. Night orders: "Call me at 0330 or earlier if in doubt. Standing orders apply: CPA 2 nm."

2345. You arrive on the bridge and read the night orders by red light. The third officer briefs you: position fixed by GPS and checked by radar range of a headland at 2340; two radar targets, a fishing vessel on the starboard bow at 6 nm, bearing steady, and a southbound tanker 8 nm ahead, opening on the port bow. Gyro error 1° high. Autopilot. Lookout on the bridge wing.

2355. You watch the fishing vessel's lights by eye: green over white all-round lights with a red sidelight visible. It is a trawler, making way and showing you its port side, so it is crossing ahead of you from starboard to port. You check it on radar: bearing steady at 045° relative, range 5.5 nm. You take over: "I have the watch."

0003. Range 4.5 nm, bearing still steady. Your standing orders want a 2 nm CPA. You are a power-driven vessel; the trawler is engaged in fishing, so under Rule 18 you keep out of its way. You alter early and substantially: 40° to starboard, to pass astern of it, and sound one short blast if it is in sight, which it is.

0020. The trawler passes 2.2 nm off on the port side. You return to the planned track, fix the position and log the manoeuvre.

0140. Rain arrives. Visibility drops to about 1.5 nm. This is restricted visibility: you call the master (situation 1 on the list), start fog signals (one prolonged blast at intervals of not more than 2 minutes), go to hand steering with a helmsman called to the wheel (the lookout stays a lookout), warn the engine room, reduce to a safe speed, and change the radar range scale to look ahead properly. You log the times.

0148. The master arrives, reviews the picture, and says: "Carry on, second officer, I'll stay up here." You still have the con. You say so aloud: "Understood, I keep the con."

This is how the principles look in practice: early detection, an early and obvious action, a timely call, and clear words about who is in charge.

Common Mistakes

Accepting the watch before seeing every target. Your relief briefing is a starting point, not a substitute for your own look.
Handing over in the middle of an avoiding action. Finish the manoeuvre first.
Using AIS as the lookout. AIS shows only vessels that transmit; your eyes and the radar find the rest.
Being sole lookout at night because the lookout was sent to do something else. If you are alone at night, you are not keeping a proper lookout.
Not calling the master because "it was probably nothing". The list says "if in any doubt".
Waiting for the master instead of acting. Calling the master and taking immediate action go together.
Ignoring fatigue. Breaking rest into short pieces leaves you exhausted even when the total looks fine.
Tidy logs written later. Record events as they happen, and never erase.

Summary

STCW Chapter VIII and Code A-VIII/2 set the principles of watchkeeping; MGN 315 is the MCA's guidance; the SMS and the master's standing orders apply them on your ship.
The OOW is the master's representative and stays responsible until the master clearly takes the con, and even with a pilot on board.
Keep a proper lookout by sight, hearing and all available means. The OOW may be sole lookout only in daylight after the master has assessed it safe; never at night.
Read and sign the standing orders and night orders, and use your own judgement on top of them.
Take over only when you are fully satisfied, never during a manoeuvre and never to someone unfit. End with clear words, and log it.
Call the master in the situations in Code A-VIII/2 paragraph 32, and whenever in doubt, and act immediately for the safety of the ship while you wait.
Hours of rest: 10 in any 24, 77 in any 7 days, no more than two periods with one of at least 6 hours, and no more than 14 hours between rest periods.
Keep the log accurately, at the time, and never erase.

Check Your Understanding

The master comes to the bridge in poor visibility and stands by the radar. Who has the con?

Answer: You do, as OOW, until the master specifically says they are taking the con and that is mutually understood. Confirm it aloud and log it.

When may the OOW be the sole lookout?

Answer: Only in daylight, and only when the master has carefully assessed the situation (weather, visibility, traffic, dangers, TSS, bridge layout and blind sectors, distractions) and is satisfied it is safe, with help immediately available to summon. Never in darkness or restricted visibility.

Your relief arrives while you are 20° into an alteration to avoid a ship crossing from starboard. What do you do?

Answer: Do not hand over. Complete the manoeuvre and confirm the ship is passing clear, then hand over the watch.

Give five of the situations in which the OOW must call the master immediately.

Answer: Any five of: restricted visibility met or expected; traffic or other ships' movements causing concern; difficulty keeping course; failure to sight land, a mark or get soundings when expected; unexpected land, mark or change in soundings; failure of engines, steering or essential navigation equipment; radio malfunction; heavy weather with fear of damage; a hazard such as ice or a derelict; any other emergency or doubt.

An officer has 12 hours of rest today in three periods of 4 hours. Is this compliant?

Answer: No. Rest may be divided into no more than two periods, and one of them must be at least 6 hours long.

What is the UK legal alcohol limit for a professional mariner on duty?

Answer: 50 mg of alcohol per 100 ml of blood, or 25 micrograms per 100 ml of breath (STCW sets 0.05% blood alcohol or 0.25 mg/l breath). Many companies set zero.

What is the difference between standing orders and night orders?

Answer: Standing orders are the master's permanent written instructions for the bridge, signed by each officer on joining and when changed. Night orders are written each evening for that night's specific situation and signed by each OOW when taking over.

You make an error in the deck log. How do you correct it?

Answer: Draw a single line through it so it remains readable, write the correct entry and initial it. Never erase or blank it out.

Why must a relief arrive early for a night watch?

Answer: To read the night orders and let their eyes adapt to the dark, so that they can see and assess every light before they accept responsibility for the watch.