SeamanshipAugust 26, 2026• 10 min read• By Safety Anchor Alarm Team

What to Record in a Ship's Log — and What You Can Leave Out

Almost every abandoned logbook failed in one of two opposite ways. Either it was kept so sparsely that nobody could answer a question with it, or it was so ambitious that keeping it became a chore and it stopped in June. The fix is not more discipline. It is knowing which entries pay you back — and the useful way to sort that is not by category but by a blunter question: who is going to ask for this, and when?

The short answer

For each passage: date, from, to, mode, distance, engine hours, crew and conditions. For the boat: every job with its date, engine hours and next-due figure; fuel taken on; money spent; what spares are aboard and where. For the paperwork: insurance, registration and licence. Everything else is for your own pleasure — worth keeping, but never at the cost of the entries above.

Sorted by Who Asks for It Later

Read the second column. An entry that nobody will ever ask for is not wrong to keep — it is just not the reason to keep a logbook, and it should never be what makes you give up on one.

What you record	Who asks for it	When	Why it earns its place
Maintenance: job, date, engine hours, next due	Future you, then the buyer	Every spring, and the day you sell	The single highest-value thing in the book. A documented service history is money at sale and the only way a three-clock schedule stays honest.
Engine hours at the end of each passage	Future you	Whenever a job is due by hours rather than date	Half of marine maintenance runs on hours. Without the readings you are guessing.
Fuel taken on: litres, cost, hours	Future you	The first time you plan a passage on range	Three fill-ups turn consumption from folklore into a number you can plan with.
Passage: from, to, distance, conditions	You, a certifying body, occasionally customs	Qualifying miles, or a question about where the boat has been	Cheap to write on arrival, impossible to reconstruct later.
Crew aboard	An insurer, and some port authorities	After an incident, or at a border	One line. Occasionally the line that matters.
Expenses: marina, parts, yard	You	When you work out what the boat actually costs	The annual figure almost no owner has, built one receipt at a time.
Inventory: what is aboard, which locker	You, at the worst possible moment	When something breaks and you own the spare already	Stops you buying the second one because you could not find the first.
Documents: insurance, registration, licence	A harbourmaster, a customs officer, a charter company	Unannounced	Photographs of the papers, aboard, offline.
Incidents: groundings, damage, near misses	An insurer or surveyor	After a claim, sometimes years later	Contemporaneous notes carry weight that memory does not.
Dolphins, sunsets, the taverna in Kastos	Only you	In February	Keep it because you want to. Just do not let it be the reason the useful half never gets written.

Do You Legally Have to Keep One?

Almost certainly not, if the boat is private and used for pleasure. The Official Log Book that people are thinking of is a commercial instrument: flag states require it on merchant and larger vessels, and they specify exactly which events must be entered — crew movements, drills, births and deaths, disciplinary matters. None of that machinery is pointed at a thirty-eight-foot cruising yacht.

What is true is narrower and more useful: there are moments when having records is worth a great deal, and none of them announce themselves in advance. An insurance claim after a grounding. A surveyor at a pre-purchase inspection. A customs officer asking where the boat has been and when. A certifying body wanting qualifying sea miles. A buyer deciding between your boat and an identical one with no history.

So keep a log because those are cheap to prepare for and expensive to improvise. Not because someone will fine you for not having one.

The Passage Entry

This is the one people picture when they think “ship's log”, and it is the one most likely to be abandoned, because it competes with arriving somewhere nice. Keep it small enough to finish in the cockpit with a drink.

Nine fields. If you only ever fill in five, make them date, from, to, distance and engine hours.
Field	Why it earns a line
Date & time	Anchors every other entry to a point in the season.
From / To	Marina, port or a lat-lon. The two ends of the day.
Mode: sail, motor or mixed	The only honest way to read a fuel figure. Ten hours of motoring and ten hours of sailing burn very different amounts.
Distance run	Accumulates into qualifying miles, and into cost per mile if you also log the spending.
Average speed	Turns a plan into a real ETA next time you consider the same passage.
Engine hours	The reading that decides when the next service is due.
Crew	Who was aboard. Small, and occasionally what an insurer or a port official wants.
Conditions	Wind, sea, visibility. What the passage actually felt like, not what the forecast promised.
Notes	The berth that was awful, the hidden rock, the chandlery that had the part. Next-time knowledge.

The field people skip is mode — whether you sailed, motored or did both. It looks like trivia and it is the difference between a fuel figure that means something and one that does not. Twenty hours logged against thirty litres tells you nothing until you know how many of those hours the engine was actually running.

There is a quiet bonus hiding in this entry: if it also notes who was aboard and in what role, it doubles as the raw material for everyone's personal sea-time record — the RYA and ASA logbooks that examiners and charter companies ask for years later.

The Half That Actually Pays

If the passage log is the romantic half, this is the half that returns money. Three records, and they compound:

Every job, with hours and a next-due figure

Not just “changed the impeller” but the date, the engine hours, and when it is next due — by date and by hours, because boat maintenance runs on three separate clocks: the calendar, the hours and the condition of the part. A record that captures only one of the three cannot tell you what is overdue.

It is also the entry that turns into cash. Two identical boats, one with a documented service history and one without, do not fetch the same price — and the one without spends longer on the market while a buyer decides how much unknown risk to discount.

Fuel, with the hours beside it

Log litres, cost and the engine hours at each fill. After three fills you know your real consumption, which is the number that decides whether a passage is within range or a hopeful guess. It is also an early warning: consumption that quietly climbs is an engine telling you something before it gets loud about it.

What is aboard, and where

The least glamorous entry and the one that saves the most swearing. A boat carries hundreds of small things in lockers nobody has opened since the last owner. Recording the spare impeller as “engine room, port shelf” is thirty seconds that stops you buying a second one in a chandlery in August at holiday prices.

The Honest Case for Paper, and Against It

A bound log at the nav station is a genuinely good object. It works with wet hands, needs no battery, survives being dropped, and reads beautifully in ten years. If the passage narrative is what you love about keeping a log, keep it in a book.

Where paper fails is not writing. It is finding. The questions a logbook exists to answer arrive years later and in a specific form: when did I last change the impeller, and at what hours? Which locker is the spare alternator belt in? What did we actually spend on the boat last season? Each of those is trivial to answer from a searchable record and genuinely hard from three volumes of handwriting, one of which stayed with the previous owner.

Which is why a lot of people end up keeping both: the paper log for the passage, and a marine logbook app for the boat's records — the service history with next-due dates and hours, the fuel, the expenses, the inventory and the ship's papers, all searchable and exportable to PDF when a surveyor or buyer asks. We built ours because our own maintenance checklist kept arriving at the same sentence: the schedule only works if you can see when each job was last done.

How to Keep It Going Past June

Every abandoned logbook was abandoned for the same reason — the entry felt like homework at the exact moment the crew wanted a beer. Three habits that survive:

Write the passage entry on arrival, not later. Ten minutes while the details are still true beats an hour of reconstruction in November that will be wrong.
Log the job when you do it, not when you finish. Hands already dirty, hours already on the display, receipt still in your pocket. This is the entry with the highest value and the shortest window.
Let the small entries be small. A fuel entry is three numbers. An inventory entry is an item and a locker. If every entry demands a paragraph, none of them get written.

And the entry almost nobody makes but everyone should: the near miss. The night the anchor dragged and you caught it, the berth you would never take again, the shallow patch that is not on the chart. Those are the notes that stop the same evening happening twice — and the sort of thing our night anchoring guide exists to make less likely in the first place.

The Bottom Line

Sort every candidate entry by who will ask for it. The maintenance record, the engine hours and the fuel figures pay you back in money and in avoided trouble. The inventory pays you back in August, in a chandlery, at holiday prices. The documents pay you back at a border. The passage log pays you back in February, which is a real return but a different currency.

Keep all of it if you enjoy it. But if the log is going to be incomplete — and most are — make sure the half that survives is the half somebody will actually ask you for.

A note on accuracy

This guide describes general practice for recreational vessels. Official Log Book requirements are set by flag state and vessel type and apply mainly to commercial and larger vessels; record-keeping obligations, customs and immigration formalities and insurance conditions all vary by country and by policy. Last reviewed on 26 August 2026. Rules, fees and permit requirements change, differ between countries, states and local authorities, and can depend on your vessel and the season — so treat this page as a starting point, not legal advice. Always confirm against the current official sources — IMO — international conventions and flag state requirements and UK MCA — Official Log Books guidance — or your national boating authority before you rely on it. Safety Anchor Alarm accepts no liability for decisions made on the basis of this page. Spotted something out of date? Tell us and we'll correct it.

Marine Logbook

Every entry on this page, kept somewhere you can search it — service history with next-due dates and engine hours, fuel, expenses, inventory and the ship's papers, exportable to PDF.

Get Marine Logbook

Frequently Asked Questions

What should you record in a ship's log?

Record the things somebody will need later, and be honest that 'somebody' is usually you. For a passage: date and time, where you left from and arrived at, distance run, engine hours, who was aboard, and the conditions. For the boat: every job done with the date, the engine hours and the next-due figure; fuel taken on; money spent; what spares are aboard and where they are stowed. For the paperwork: insurance, registration and licence details. Everything else — the dolphins, the sunset, the meal in the taverna — is worth keeping because you enjoy it, not because anyone will ask for it.

Is a logbook legally required on a private boat?

Generally no, for a recreational vessel. The legally mandated Official Log Book belongs to commercial and larger vessels, where flag-state rules set out exactly which events must be entered and how. A private yacht is usually under no such obligation. That said, records still matter in situations that have nothing to do with the law being enforced on you: an insurance claim, a survey, a sale, a customs question about where the boat has been, or a certifying body asking for qualifying sea miles.

What should go in a passage entry?

Date and time, departure point and destination, whether you sailed or motored, distance run, average speed, engine hours at the end, and who was on board — plus a line or two of description while it is still fresh. That set is small enough to fill in over a drink on arrival and complete enough to answer the questions that come up months later, from 'how much fuel does this boat really burn' to 'how many miles have I logged this season'.

How do you log engine hours and why do they matter?

Note the reading at the end of each passage and at every service. They matter because roughly half of a boat's maintenance runs on hours rather than dates — oil and filters by hours, the impeller by the calendar regardless of use, anodes by condition. Without an hours record you cannot tell which jobs are due, and 'it was done last season' stops being a useful answer for anything that wears rather than ages.

Paper logbook or an app?

Both work for writing. They differ completely at finding. A bound book at the nav station is pleasant to keep and impossible to search — the question you will actually ask in three years is 'when did I last change the impeller and at what hours', and that means leafing through a book you may no longer own. An app keeps the same entries searchable, attaches the receipt photo to the job, reminds you when something is next due, and exports to PDF when a surveyor or buyer wants the history. Many people keep both: the paper log for the passage narrative, the app for the boat's records.

App