The logbook, sometimes called the ship's log or deck log, is the essential document that records in chronological order the life of your boat, the events of each passage, technical data and the composition of the crew. It is the memory of your time at sea, and far more than an administrative formality.
Is a logbook mandatory?
It depends on your flag State and on the category of navigation you undertake. Most national administrations make a logbook compulsory as soon as a vessel operates offshore — beyond the coastal limits set in their own regulations — and for any vessel operating commercially. For pleasure craft staying close to shore, many regimes leave it optional.
For commercial vessels the question does not arise: the official log book, the oil record book and the radio log are required by international conventions, and the ISM Code expects the operator to keep records that demonstrate how the ship is actually run.
Even where it is not strictly required, keeping a logbook remains strongly recommended, for reasons that matter the day something goes wrong: it supports your safety on passage, it serves as legal evidence for your insurer after damage, and it substantiates your itinerary during a customs or coastguard check.
The logbook fills three essential roles: safety (an accurate picture of where you are and how you got there), legal (evidence in the event of a dispute or a claim) and memory (the travel diary of your maritime adventures).
What should a logbook contain? (The essential content)
The content of your logbook should make it possible to reconstruct the passage at any point in time. Here is the information worth recording:
📋 Permanent information (first page)
- Vessel identification: name, registration number, type of vessel, length, flag
- Owner information: name, contact details, insurance policy number
- Crew list: full names, role on board, emergency contacts
✅ Before departure (departure checklist)
- Safety checks: safety equipment (lifejackets, flares, liferaft), VHF operational, navigation lights
- Levels: fuel, fresh water, gas
- Crew briefing: safety instructions, man overboard procedure
- Passage plan: destination, intended route, ports of refuge, estimated times
- Weather forecast: source consulted, time, forecast for the area
⚓ During the passage (to be completed regularly)
To be recorded hourly, or at every significant change:
- Date and time: watch handover times
- Position: GPS coordinates or estimated position
- Course: course steered (compass or GPS)
- Speed: speed through the water from the log
- Observed weather: wind force and direction (in knots and degrees), sea state, visibility, barometric pressure
- Settings: sail plan in use (mainsail, genoa, spinnaker) or engine revolutions, together with the running hours counter reading
📝 Notable events
- Significant changes of course or sail plan
- Observations: vessels sighted, hazards (wrecks, shoals), weather phenomena
- Incidents or damage, however minor: equipment failures, falls, illness on board
- Important VHF communications: distress calls overheard, contacts with the authorities
Which logbook should you choose: paper, app or template?
The right medium depends on the kind of sailing you do and on your own preferences. Here is a comparison to help you decide.
The paper logbook (the traditional choice)
Advantages:
- Complete reliability: no dependence on a battery or a network
- Legal value that nobody disputes
- Genuine keepsake value in the handwriting itself
- Easy for every crew member to consult
Drawbacks:
- Vulnerable to salt water and damp
- Tedious to fill in, especially in a seaway
- No automatic backup
Where to buy one? Any chandlery sells pre-formatted logbooks designed for yachts and small craft, with all the necessary columns already laid out. Several nautical publishers produce their own versions, and the cost is modest.
Apps and software (the modern choice)
Advantages:
- Automated data capture: GPS track recorded, weather retrieved automatically
- Easy sharing with the crew or with rescue services
- Secure cloud backup
- Export to a range of formats
Drawbacks:
- Dependence on battery power (carry a power bank)
- Potential cost (monthly or annual subscriptions)
- Legal acceptance to be checked with your flag State, app by app
- Requires a little time to learn
Examples of applications: Smart Sailors, BoatOn Book, Deckee, Navionics with its logbook module, and iNavX all offer this functionality.
🚀 Smart Sailors: the complete solution for your digital logbook
Smart Sailors stands out as a professional solution that automates the keeping of your logbook while safeguarding regulatory compliance. The application records your GPS track automatically, retrieves live weather data, and produces reports that stand up to maritime requirements.
Key features:
- Automatic recording of position, course and speed
- Integration of weather bulletins and forecasts
- Complete management of the crew and of the vessel's documents
- Compliant PDF export for authorities and insurers
- Real-time sharing with family and friends ashore
- Maintenance tracking and engine running hours
💡 Would you like to make your logbook easier to keep?
👉 Request a free Smart Sailors demo
See how Smart Sailors can transform your time on the water by automating your logbook while keeping you on the right side of your legal obligations.
Free templates (PDF or Excel)
Advantages:
- Completely free
- Customisable to your own needs
- Can be printed in advance
Drawbacks:
- Less practical under way (requires printing or a computer)
- No automated data capture
- Risk of loss if not backed up
Why keeping a logbook matters, even when it is not compulsory
Beyond the legal obligation that applies offshore and to commercial operation, the logbook offers benefits that every boat owner can appreciate.
🛡️ Safety first
The logbook allows every crew member, particularly at a watch handover, to grasp the situation immediately: where are we? What is the weather doing? What has happened during the last watch? In an emergency, that information can be vital to rescue services.
It also helps you anticipate problems. By recording engine running hours regularly, you can plan servicing before something fails. By tracking consumption, you avoid running out of fuel or water.
⚖️ Legal evidence
After damage or a claim, your marine insurer will often ask for the logbook in order to reconstruct the circumstances of the incident. It can make the difference between settlement and refusal of cover.
During customs or coastguard checks, especially in international waters, the logbook lets you prove your itinerary and account for your port calls. Maritime authorities may also ask for it during a routine inspection.
📖 The keepsake
Beyond the practical side, your logbook becomes a genuine sea-going travel diary. Reading your own notes years later brings the passages back to life: the dolphins met offshore, the gale you sailed through, that perfect anchorage in a deserted bay.
Many offshore skippers describe the log as the thread that runs through their voyages — the one document they would not sail without.
Practical advice for keeping your logbook well
Establish a routine: nominate someone on each watch to fill in the log. Ideally, record the entries hourly on an offshore passage, or at every significant event when coastal cruising.
Be precise but concise: record facts, not prose. A GPS position, a course and a weather observation are enough. On the other hand, never skip an incident, however small it seems at the time.
Protect a paper log: use a waterproof cover or keep it in a dry bag, and write with permanent ink.
Back up your digital data: if you use an application, switch on automatic backup and export your data regularly.
Conclusion
The boat logbook is far more than a regulatory requirement for offshore passages: it is the skipper's best ally for sailing safely, staying protected legally, and preserving the memory of your time at sea.
Whether you are an occasional coastal sailor or a seasoned offshore navigator, and whether you choose a traditional paper book, a modern application such as Smart Sailors or a customised spreadsheet template, what matters is keeping the document rigorously.
Do not skip this essential step. Start on your next passage by seeing how Smart Sailors can automate the task for you. Your safety, your insurer and your memories will all thank you for it.
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