Crew planning: rotations and MLC rest hours

Thursday, 22:30. The crewing manager gets a message from the ship: the second engineer due to join at Saturday's crew change in Las Palmas has just noticed that his medical certificate expires in twelve days — right in the middle of his tour. Too late to get an appointment with an approved seafarers' doctor, too late to find a qualified relief for that engine type. The crew planning for the whole fleet lived in a shared spreadsheet, and nobody had cross-checked the medical's expiry date against the dates of the rotation.

That scene is expensive, and not only in phone calls. An international crew change means flights, sometimes visas, a hotel night: allow €1,500 to €4,000 of logistics per seafarer, and double that once tickets have to be rebooked at short notice. A ship waiting alongside for her officer loses a tide, a rotation or a weather window. And an inspection that turns up non-compliant rest hours or a lapsed certificate of competency exposes the vessel to outright detention, recorded in the public databases of the Port State Control regimes — Paris MoU, Tokyo MoU, USCG. The crew plan is not an HR document: it is an operational document, on the same level as the maintenance plan.

Managing document expiry dates — STCW certificates, medicals, training endorsements — has its own dedicated guide: crew certificate management under STCW and MLC 2006. This article deals with the layer above: the plan itself. How to build rotations that hold, run crew changes that hand over the real condition of the ship, and demonstrate compliance with MLC 2006 rest hours on the day an inspector asks for the records.

Why crew planning in a spreadsheet becomes an operational risk

In most small and mid-sized shipping companies, the crew plan lives in a shared workbook: one tab per vessel, one row per seafarer, a colour code per status. The tool looks adequate — right up to the day it is not. The failure modes are always the same:

• Manual cross-checking of expiry dates: licences, medicals and training certificates are verified from memory when a name goes into a cell, and never rechecked when the rotation slips by a week.
• No view of rest hours: the spreadsheet plans presence on board, not hours of work. It cannot tell you whether the intended watch system still meets the MLC 2006 minima once port calls and manoeuvres are added.
• Dependence on one person: whoever keeps the file is the only one who can read it; their leave freezes every decision, and their departure erases the logic behind the plan.
• No usable history: rebuilding a seafarer's sea service record to revalidate a certificate means digging through dozens of archived versions of the file.
• Competing versions: the ship is looking at Monday's file, the office at Wednesday's; the crew change is arranged against two different realities.

These are exactly the limits we quantified for maintenance in our analysis of the real cost of running a fleet on spreadsheets. The difference is that here, the failure does not block a work order: it blocks a seafarer at the airport, or a ship at the berth.

What does MLC 2006 require for rest hours?

MLC 2006 requires a minimum of ten hours of rest in any 24-hour period and 77 hours in any seven-day period. Rest may be divided into no more than two periods, one of which must be at least six hours long, and the interval between consecutive periods of rest must not exceed fourteen hours. These minima, mirrored in section A-VIII/1 of the STCW Code for watchkeeping personnel, are checked against the records, hour by hour.

Exceptions exist — collective agreements authorised by the flag State, specific splitting arrangements — but they are tightly framed and have to rest on written provisions, not be improvised on board. Emergency calls, drills and safety operations remain possible at any time; they give rise to compensatory rest that the master must arrange as soon as practicable.

What the inspector actually checks

• The posted table of shipboard working arrangements: the standardised document describing, position by position, the schedule of service at sea and in port, in the working language of the ship and in English.
• The individual rest hour records: each seafarer's actual hours, kept day by day, signed by the seafarer and by the master or a person authorised by the master, with a copy handed to the seafarer.
• Consistency across the lot: a perfectly filled-in record that contradicts the deck log, the port call times or the manoeuvring reports counts against the vessel, not for it.

These checks come up in flag State and MLC inspections as well as in Port State Control: rest hour deficiencies are among the classic findings, and the serious ones lead to detention. Our guide on avoiding detention in Port State Control covers how these inspections work and how to prepare for them.

Compliance is decided when the plan is built

A six-on six-off watch system with two people leaves, on paper, twelve hours of rest per day. Add an arrival in port during the rest period, a manoeuvre, a bunkering, and the day drops below ten hours — without anyone having decided anything. On the tight rotations of ferries and passenger vessels, where port calls follow one another all day, the margin is structurally thin: it is the vessel's manning level, not the goodwill of the crew, that determines compliance. Rest hours cannot be made up afterwards; a plan that does not make them achievable is non-compliant by design.

The stakes go beyond compliance. Casualty investigation reports regularly cite watchkeeper fatigue among the contributing factors, particularly in night-time groundings with a single fatigued officer on the bridge. A plan that exhausts its crews always ends up paying for it — in breakdowns, in accidents or in resignations.

Building the crew plan: rotation patterns by fleet segment

A rotation is a trade-off between four constraints: operational continuity, accumulated fatigue, the cost of crew changes and the depth of the pool of qualified seafarers. There is no universal pattern — every segment has its own standards:

Whatever the pattern, three rules hold everywhere:

• Overlap on key positions: twenty-four to forty-eight hours of overlap between the off-signer and the on-signer on critical functions — master, chief engineer — are worth more than any written report. When overlap is impossible, the handover has to be documented in the system, not on the quay.
• Pool depth: two to three qualified seafarers, documents in date, for every key position on every vessel. It is the qualification matrix — who can hold which position, on which vessel, under which flag — that makes the plan robust to the unexpected.
• Firm milestones: rotation frozen at D−30, crew changes confirmed and tickets issued around D−14, final document check at D−7. Every operator sets its own lead times, but a plan without milestones is renegotiated permanently, and every renegotiation costs plane tickets.

No assignment without valid documents for the whole tour

The rule that prevents most incidents fits in one sentence: a seafarer can only be scheduled if every one of their documents — certificates of competency, medical certificate, training certificates — remains valid for the full length of the tour, plus a margin. A crew change easily slips by a week or two: weather, a breakdown, a rescheduled port call. A margin of thirty days beyond the planned sign-off date absorbs most of the contingencies.

The mechanics of document tracking — which documents to follow, at what horizons, how to organise renewals and revalidations — are covered in our guide to crew certificate management. What matters here is the link between that tracking and the plan: as long as the two live in separate files, the cross-check depends on one person's vigilance. A crew module integrated with the CMMS makes the cross-check automatic: assigning a seafarer whose document expires mid-rotation is flagged the moment the assignment is entered — early enough to organise the renewal, or to change the name without breaking the whole rotation.

The same seafarer file feeds the sea service records: every recorded tour documents time served by capacity and by vessel type, which is exactly what administrations ask for when revalidating a certificate. What used to take days of digging through old versions of the spreadsheet becomes a one-click export.

A handover transmits a ship, not just a position

A successful crew change transmits two things: a role and the real condition of the vessel. The chief engineer signing off takes weeks of observations with him — a bearing he was watching, a pump whose noise he knew, parts expected at the next port call, an agreement made with the office. If all of it lives in his head or in a personal notebook, the fleet loses its memory at every rotation, and the joining officer starts from zero on a ship he does not yet know.

What the handover must contain

• Work orders in progress: status, parts on order, jobs planned for the next port call — the full life cycle of the work orders must be readable by the on-signer without a verbal explanation.
• The recent history: failures and anomalies of the past weeks, recorded in the engine room logbook, with the readings taken.
• The job instructions: the maintenance job plans that standardise the work, precisely so that its quality does not depend on who happens to be on board.
• Stock and orders: critical levels, deliveries expected at the port call, supplier disputes in progress.
• The watch points: drifting parameters, observations awaiting a decision, commitments made to the owner or the charterer.

When the handover lasts four hours

Forty-eight hours of overlap is a luxury many operations cannot afford: on a CTV or a ferry, the crew change happens at the port call, in a few hours, sometimes between two commercial rotations. That is exactly where a shared system changes the nature of the handover: the joining officer reads the vessel's history, the open work orders and the latest observations before even stepping on board, from the mobile app — offline included, with synchronisation as soon as the network comes back. The twenty minutes on the quay are then spent discussing what matters, not transmitting everything.

Access rights follow assignments

A live plan moves crews from one vessel to another, and access to data has to follow the same movement. The mate taking a temporary command must see the data of his ship — and nothing else. The officer who has signed off must no longer be able to close work orders on his former vessel. Shared generic accounts — "chief@vessel", password taped to the bridge console — are a recurring audit finding, and they destroy traceability: there is no way to demonstrate who actually signed off a job. Role and permission management synchronised with the assignments in the plan solves both problems at once: access opens on signing on, closes on signing off, and every action stays signed by its author — exactly the kind of evidence an ISM auditor or an inspector comes looking for.

Leaving the spreadsheet behind: the three-stage method

1. Import the seafarer files. Certificates of competency, medicals, training certificates, sea service records and tour history. This is the moment to clean up: duplicates, lapsed documents, seafarers who have left. Expect most of the project's effort to sit in this stage — and it is an investment, not a cost, because this data is used every day afterwards.
2. Set the rules. The qualification matrix by position and by vessel, the required margins on document expiry dates, the rotation patterns and the rest hour rules specific to each operation. It is these rules that turn the plan from a drawing into a system able to flag a non-compliant assignment before it becomes a problem.
3. Build the rotations in the tool and keep the records as you go. Assignments generate the consolidated fleet plan; rest hours are entered on board, day by day, on mobile, rather than reconstructed at the end of the month. After the first inspection that passes without tension, nobody asks for the spreadsheet back.

This transition follows the same logic as digitalising maintenance — data migration, rule definition, change management — described step by step in our complete maritime CMMS guide.

Key takeaways

Crew planning is a system of constraints: documents valid across the whole rotation, rest hours compliant with MLC 2006 from the design of the watch system onwards, crew changes that hand over the real condition of the vessel, access rights that follow assignments. A spreadsheet displays names in cells; it verifies none of these constraints. As long as the fleet is small and nothing moves, the gap stays invisible. It shows itself the day a crew change slips, an inspector asks for the rest hour records, or the only person who understands the file is on leave.

Treating crew planning as a managed process — seafarer files kept current, automatic expiry checks across the length of each rotation, rest hour records kept on board, documented handovers — costs less than a single detention. That is the role of the crew module of a maritime CMMS: connecting seafarers, their documents, their assignments and the vessel's history in one system, available from the ship and from the office, even without a connection. Smart Sailors is designed in Marseille by seafarers and deployed on more than 700 vessels. Request a demonstration on your own fleet, or take a look at our plans.