Hours of Rest, Fatigue and Safe Manning

Safe manning: what a safely manned ship is

In short: Read OOW duties and the safe navigational watch first: this topic is about the people behind the watch. A ship is safely manned when it carries enough officers and ratings, with the right certificates and skills, to do every safety job on board — at peak workload, and without anyone breaking the rest rules (MSN 1868 (M) Amd 1, SOLAS V/14).

The jobs the crew must be able to do

The MCA considers a ship safely manned when the crew can (MSN 1868 (M) Amd 1 3.1–3.2):

• keep a safe navigational, engineering and radio watch;
• moor and unmoor the ship safely;
• manage the ship’s safety functions when it is stopped or nearly stopped at sea;
• carry out the operations that protect the marine environment;
• give medical care on board;
• work all watertight closing arrangements, keep them in good order, and put together a competent damage-control party;
• use all fire-fighting and emergency equipment and the life-saving appliances;
• run the main propulsion and auxiliary machinery.

Who is responsible

• The owner or operator must make sure the ship is safely and adequately manned (MSN 1868 2.1).
• Manning must cover peak workload (arrival, departure, bad weather, emergencies), not just a quiet day at sea (MSN 1868 2.2, 6.6).
• Except in small ships, there should be enough deck officers so that the Master does not have to keep regular watches — and enough engineers so the Chief Engineer does not either (MSN 1868 3.2).
• The Master must keep watchkeeping arrangements adequate at all times, including a proper look-out. The UK does not accept the OOW as the sole look-out in darkness or restricted visibility (MSN 1868 13.2).

The rules behind it

• SOLAS V/14: the flag State sets the minimum safe manning and issues a Safe Manning Document.
• IMO A.1047(27): Principles of Minimum Safe Manning.
• STCW and the UK STCW Regulations 2022: certificates and watchkeeping.
• MLC (Hours of Work) Regulations 2018: hours of rest.
• MSN 1868 (M) Amd 1 explains how the UK applies all of this. It replaced the original MSN 1868 on 10 January 2023.

The Safe Manning Document (SMD)

In short: Ship proposes → flag approves → ship keeps the minimum. The SMD is the flag State’s document that states the minimum number and grades of crew. It is issued only after the owner’s own assessment has been accepted (MSN 1868 9–10).

Which ships need one

• All UK seagoing ships of 500 GT or more.
• UK seagoing passenger ships under 500 GT on international voyages.
• Other vessels may hold one voluntarily, but every vessel must be adequately manned for its work and area (MSN 1868 1.3–1.5).
• Yachts: 500 GT or more need an SMD (MSN 1858 (M) Amd 2 14).

Three steps: propose, approve, keep

1. The ship (owner) proposes. The owner assesses every task at peak and routine workload and sends a justified proposal on form MSF 4227. It must show how the crew handles emergencies and how the hours-of-rest rules are met (MSN 1868 2.2, 9.1–9.2). The Master and crew are consulted; if they cannot agree, the MCA decides and may ask for a practical demonstration of the crew (6.1–6.2).
2. The flag (MCA) approves and issues the SMD in the SOLAS format (10.1–10.2).
3. The ship keeps the minimum. The SMD stays on board, ready for inspection, and manning never drops below it (10.2, 10.4). The agreed manning schedule is displayed in the crew accommodation (6.7). The record of the consultation is kept for 5 years (7.1, 7.4).

When the SMD stops being valid

• The ship changes trading area, construction, machinery, equipment, operation or maintenance method and no new proposal is sent.
• The ship persistently fails to meet the rest-hour rules (MSN 1868 10.3).
• Short of crew through an exceptional event? The owner can ask the MCA for a time-limited exemption until the replacement joins — only if the ship can still operate safely (MSN 1868 11.1).
• On the bridge: your Second Officer signs off sick and no relief can join before sailing. You cannot just sail one officer short: the company asks the MCA for an exemption first.

Manning scales: merchant ships and yachts

In short: The tables are a minimum and a guide. The real number comes from the assessment, and extra officers are strongly recommended where needed to prevent fatigue (MSN 1868 4.3, MSN 1858 14).

Merchant ships — deck officers (MSN 1868 Annex A)

Navigational watch ratings must hold STCW II/4 certificates.

Yachts of 24 m and over (MSN 1858 (M) Amd 2, 14.1)

• YM = Yachtmaster (RYA); MOY = Master of Yachts (IYT).
• An MCA Master II/2, code vessels under 200 GT can replace YM Offshore / MOY limited (150 NM version) or YM Ocean / MOY unlimited (unlimited version).
• Some Chief Mate posts may be a dual deck and engineer role if the officer is qualified in both — never the Master.
• MSN 1858 (M) Amd 2 (18 May 2026, replaces Amd 1) covers commercial and private yachts and sail training vessels of 24 m and over, under 3000 GT, no cargo, 12 passengers or fewer (1.3).

Smaller vessels and their codes

• Commercial yachts of 24 m and over are built and equipped to the REG Yacht Code (Red Ensign Group); deck officer manning comes from MSN 1858.
• Small commercial vessels under 24 m take their manning from the code they are certified under: MGN 280 (M) (Small Vessels Code) or, for workboats and pilot boats, the Workboat Code Edition 3 (in force 13 December 2023, replacing MGN 280 for those craft).
• ❌ Trap: it is MGN 280, a guidance note — not “MSN 280”.

Hours of rest: the 10 / 77 / 14 rule

In short: 10 h rest in any 24 h, 77 h in any 7 days, at most 2 blocks with one of at least 6 h, and never more than 14 h between rests (STCW A-VIII/1, MLC Standard A2.3, MSN 1877 (M) Amd 2 4.2).

Who is covered

• STCW A-VIII/1: everyone who keeps a watch (officers and ratings) and everyone with designated safety, pollution-prevention and security duties.
• MLC 2006: all seafarers.
• UK: MSN 1877 (M) Amd 2 applies the MLC Hours of Work Regulations 2018 to UK seagoing ships, including charter yachts and sail training vessels — but not pleasure vessels or fishing vessels (2.1, 2.3).

The numbers

• 10 h of rest in any 24 h.
• 77 h of rest in any 7 days.
• The daily rest may be split into no more than 2 periods, one of at least 6 consecutive hours.
• The interval between two rest periods must not exceed 14 h.
• “Any 24 h” is a rolling window, not midnight to midnight.
• Short breaks (a meal, a coffee) do not count as rest.
• MLC lets each flag choose: a maximum of work (14 h in any 24 h, 72 h in any 7 days) or a minimum of rest (10 h / 77 h). The UK uses minimum rest.

Say it as one line: “10 a day, 77 a week, 2 blocks — one of 6 — and never 14 without rest.”

Checking a watch pattern

• A two-watch yacht runs 6-on / 6-off: work 0000–0600 and 1200–1800, rest 0600–1200 and 1800–2400. That is 12 h in two 6 h blocks, intervals of 6 h, 84 h a week: it complies.
• Now add a 1 h drill at 0900 in the morning rest. The rest becomes 0600–0900, 1000–1200 and 1800–2400: 11 h, but in 3 periods. That breaks the two-period rule unless an authorised exception applies — so give compensatory rest and plan drills better.

Exceptions, emergencies, call-outs and drills

In short: The rules bend in only three ways: an authorised exception for watchkeepers (still at least 70 h a week), the Master’s power to suspend the schedule in an emergency, and compensatory rest after call-outs.

Watchkeeper exceptions (MSN 1877 5)

Short form: “on 2 days a week at most: 3 blocks, one of 6 h, and 70 h a week”. In full:

• daily rest split into up to 3 periods: one of at least 6 h, the others at least 1 h;
• intervals between rest periods still 14 h or less;
• on no more than two 24 h periods in any 7 days;
• at least 70 h of rest in any 7 days;
• for no more than 2 consecutive weeks, then a normal period at least twice as long before the next run of exceptions;
• in the UK the exception must come from a collective or workforce agreement and be authorised by the MCA (5.1–5.5).

Trap: “6 h a day is enough under an exception.” No — the 6 h is the shortest allowed length of the longest block, not the daily total. What an exception lowers is the weekly minimum (77 → 70 h) and the number of blocks (2 → 3).

Emergencies

• The Master may suspend the rest schedule for the immediate safety of the ship, people on board or cargo, or to help another ship or person in distress.
• As soon as the situation is normal, everyone who lost rest gets an adequate rest period (MSN 1877 7.1, MLC Standard A2.3).

Call-outs and drills

• Being on call is not work. If your rest is disturbed by a call-out (an engine alarm, a mooring call), you get compensatory rest (MSN 1877 4.1.2).
• Musters and drills must be run so that they disturb rest as little as possible and do not cause fatigue (MLC Standard A2.3). How often drills are held is covered in alarms, musters and drills.

Young seafarers

In short: Nobody under 16 may work on a ship covered by the MLC. Young persons (16 and 17) get more rest, regular breaks and no night work (UK young persons summary, form MSF 4158, carried with every crew list).

The rules for 16- and 17-year-olds

• 12 h of rest in every 24 h.
• 2 days of rest in every week.
• If the daily work is more than 4½ h, a break of 30 min.
• No night work — “night” is at least 9 consecutive hours including midnight to 0500 — unless training needs it and the work is listed as safe for young persons.
• A risk assessment before they start work, and a valid medical certificate.
• If a young person works a watch schedule under the adult rules, they must get compensatory rest and be protected from risk.

Memory hook

“4½ on, ½ off — and 12 off a day.” Compare with adults: 10 h a day.

Schedules and records

In short: Rest is planned in a posted table and proved with signed records. The MCA checks both (MSN 1877 6–8, MSN 1868 7.2–7.3).

The posted table

• A table of shipboard working arrangements shows each position’s watch duties and minimum rest.
• It is posted in a prominent, easily reached place, in English and in the ship’s working language if different (MSN 1877 6.1–6.3).

The records

• A record of daily rest for every seafarer, completed at least monthly in arrears.
• Signed by the Master (or an authorised person) and the seafarer, who gets a copy.
• Kept for at least 1 year and available for inspection at any time (MSN 1877 8.1–8.4).
• If the records show the crew is too small to stay within the rules, the MCA makes the owner increase the manning (MSN 1868 7.2).
• On the bridge: write the hours honestly. A “clean” record that hides a 20-hour day hides the fatigue — and after an accident it is evidence.

Fatigue

In short: Fatigue is a reduction in physical and/or mental capability resulting from exertion (IMO definition, COSWP 3.6). It is linked to accidents, injuries and pollution — which is why manning and rest rules exist at all.

Who must manage it

• The company and the Master organise the work to minimise fatigue; each seafarer looks after their own health and safety (COSWP 2026 3.6.3).
• Safe manning must take minimising fatigue into account; guidance is in MGN 505 (M) Human Element Guidance Part 1 — Fatigue and Fitness for Duty (MSN 1868 2.3).
• A watchkeeper arrives on the bridge rested: an outgoing OOW does not hand over the watch to a relief who is not fit.
• COSWP (Code of Safe Working Practices for Merchant Seafarers) is published for the MCA by TSO and must be carried on UK merchant ships. Use the current edition: 2026 (published 18 March 2026).

On the bridge

• Warning signs: heavy eyes, nodding off for seconds, missed reports, slow reactions, irritability, poor decisions.
• If you feel it: stand up, move, keep the BNWAS on, use the look-out actively — and call the Master rather than carry on alone.
• Plan ahead: long coastal passages, port calls and drills on the same day are where rest disappears. Raise it before sailing, not after the near-miss.