The record sheet itself
Most companies use a template built around the format suggested in IMO guidance (originally MSC/Circ.1014) and the ILO's guidance under MLC Guideline B2.3: a grid per seafarer, per day, with hours of the day across the top and rest periods marked in. Some companies still fill this in on paper at the end of each watch or shift; a growing number use dedicated rest-hour software, often tied into the ship's electronic logbook, crewing, or payroll system, which can flag a shortfall automatically as entries are made rather than weeks later.
Who fills it in, and who signs it
The normal workflow is: the seafarer (or their department head) records actual rest taken, not just what was scheduled or rostered — a rostered 8 hours off doesn't count if a fire drill, cargo operation, or safety duty cut into it. MLC requires the record to be signed by both the seafarer and a responsible person (the master or an authorized officer), and for the seafarer to receive a copy of their own record. That double sign-off is one of the specific things a PSC officer checks — see what inspectors look for.
Retention and availability
Records need to be kept on board and available for a period set by the flag state and company procedures — commonly at least the current and previous data-retention window required by the flag administration, often around 6–12 months, so they can be produced during an inspection or an incident investigation. They're also the primary evidence a company's own internal audits and the ship's safety management system use to spot a pattern before it becomes a problem.
The recurring failure mode: fitting the record instead of the schedule
The problem regulators and unions describe most often isn't a missing record — it's a record that's been quietly adjusted to look compliant after a schedule that wasn't. A night that was actually interrupted gets logged as a clean 10 hours; a split rest period that was really three short breaks gets written up as two. This is sometimes described in the industry, only half-jokingly, as making the numbers "fit." It's a real compliance risk (falsified records are treated seriously under PSC and can support a detention on their own), and more importantly it defeats the entire point of the record: catching a fatigued crew member before, not after, something goes wrong.
Where an independent check helps
Cross-checking a planned schedule before it's worked — rather than only reconciling the record afterwards — catches problems while they're still fixable: a watch rotation that quietly creates a 16-hour gap between rest periods, or a week that looks fine day-by-day but never reaches 77 hours of rest in total. That's exactly the gap the calculator on this site is built to close: run a proposed roster or a week you've already worked through it, and see precisely which rule (if any) it fails, before it becomes a line item in a PSC report.