Sailing Logbook Guide: What to Record and Why

The log is a working navigation and maintenance tool, not a diary written from memory at the end of the week. It supports handover between watches, shows trends, preserves decisions, and gives rescuers or technicians better evidence. Paper remains readable without electrical power, while an electronic log can add automatic data. Choose a primary record and a backup appropriate to the voyage.

Record the Basics

Start every trip with vessel name, date, crew, skipper, departure point, destination or operating area, fuel, water, battery state, engine hours, and relevant defects. Use a consistent clock and write the time zone. Number pages or protect electronic records from silent editing. Never erase an error in a way that hides the original entry; correct it clearly according to the log's method.

Make entries at an interval suited to the passage and whenever something important changes: course, sail plan, engine state, weather, visibility, watch, position source, or destination. Harbour movements and short day sails may use event-based entries. Offshore watches need a defined routine. The skipper decides the system before departure and explains it to everyone who writes.

Use fixed units and a small legend inside the cover. Write knots, nautical miles, engine hours, litres or gallons, and pressure units explicitly. Consistency prevents a later reader from mistaking a tank percentage for a measured quantity or speed over ground for speed through water.

Capture Navigation and Weather

Write latitude and longitude with hemisphere, or another unambiguous position reference, plus the source and time. Record whether course and bearing are true, magnetic, or compass. Note speed through water or over ground explicitly. Include wind direction and strength, pressure when available, visibility, cloud, precipitation, sea state, and current observations.

Record the route actually steered and reasons for meaningful changes, such as traffic, weather, depth, or crew condition. A screenshot alone can lose context or become unavailable. Cross-check electronic positions with suitable independent information and log the check. Avoid filling blanks later with invented precision; mark an estimate as an estimate and record the next reliable fix.

When a position comes from dead reckoning or estimation, label it accordingly. Record the last reliable fix and the inputs used. The distinction preserves uncertainty for the next navigator instead of making an approximate mark look equal to an observed electronic or visual fix.

Track Maintenance

Engine starts and stops, hours, charging, fuel changes, alarms, temperatures, leaks, bilge activity, and unusual sounds belong in the log or a linked maintenance record. Note inspections and work with part, date, engine hours, person, and result. A statement such as “battery bad” is less useful than measured voltage, load, charger state, and symptom time.

Record groundings, collisions, injuries, near misses, equipment failures, and calls for assistance promptly and factually. Preserve radio times and provider instructions. Do not speculate about blame in the factual event record. Photographs, receipts, and detailed service notes can be referenced by filename or number so the log remains readable.

Agree who owns each entry during watch changes and harbour manoeuvres. A log that belongs vaguely to everyone can be missed by everyone. The writer should read back critical numbers when another crew member supplies them, especially position, course, depth, and time.

Build a Useful Habit

Keep the log, pencil, light, and reference format where the watch can use them safely. Pre-print fields for repeated information but leave room for plain-language notes. One person should review entries at watch change and before arrival. Missing information is easiest to recover while the event is recent.

After the trip, compare plan with outcome. Review fuel and water use, average progress, forecast changes, defects, and decisions that deserve a new checklist item. Transfer maintenance actions to the proper schedule instead of leaving them buried in voyage notes. Back up electronic records and store paper logs dry. A log becomes valuable across seasons when names and units stay consistent.

Choose entries that support decisions

Record departure and arrival, position, course or route, weather and sea state, sail plan, engine use, fuel, water, battery state, crew, and notable events as relevant to the trip. Use consistent units and name the source of a forecast or position when that matters. The exact format can be paper or digital, but it must remain usable on the boat.

Avoid turning the log into a diary that hides the operational facts. A short note such as "reefed after sustained heel and heavy helm" connects conditions, decision, and result. That is more useful later than "windy afternoon."

Set event-based prompts

Make entries at departure, major course changes, weather changes, sail changes, engine start and stop, incidents, and arrival. Add a regular time interval suited to the passage and boat procedure. Event prompts capture the moments when the plan changed, while timed entries prevent a quiet period from disappearing.

The marine forecast guide helps you record the forecast zone, issue time, and expected changes. The compass-course guide shows why the reference for a course should be named rather than assumed.

Make entries auditable

Write clearly enough that another crew member can continue the record. Correct an error without making the original unreadable where the log method requires that. Mark estimates as estimates. Do not invent a precise time, position, or quantity after the fact.

For an incident, record observed facts, actions, communications, and times. Separate what someone saw from what the crew later concluded. Follow current legal, insurer, employer, or organizational requirements for any formal record. Those requirements vary and may be more specific than a personal sailing log.

Use the log for maintenance

Engine hours, battery behaviour, fluid use, bilge changes, pump cycles, rig observations, and recurring faults can reveal trends. Link an entry to the maintenance record when work is required. The maintenance checklist explains how to turn an observation into an owned, dated action.

Do not wait for a failure before recording the normal state. A dry bilge, usual charging result, expected cooling flow, or normal engine sound gives later changes something to be compared with.

Review after the passage

Compare planned and actual route, time, weather, consumption, and crew workload. Note which decision worked and which information was missing. Update the next passage plan or checklist with one concrete change.

Keep logs protected and backed up according to their format. A paper book needs a dry accessible place. A digital log needs power, access, and a backup that does not depend on one device. The habit succeeds when the record survives and informs the next sail, not when every page looks perfect.

Use SailStarter's position-fixing lesson to practise one complete log entry. Start with a timed position and name its source. Add course reference, speed type, wind, sea, visibility, sail plan, engine state, and one observation that affected the route. Hand the entry to another sailor and ask what they cannot reconstruct. Improve the template, then use it on every short trip until the habit survives a busy arrival. The best log is not the most ornate. It is the record the crew can maintain accurately, read quickly, and connect to navigation, safety, and maintenance decisions.

Create a one-page legend for abbreviations, units, time zone, position format, and crew initials. Keep it with the log. Consistency prevents a later reader from wondering whether a number was depth, distance, or speed, or whether a time was local or another reference.

For longer passages, define who makes entries and who checks them. A handover should include the last position, course, weather, traffic, sail plan, engine state, and next expected event. The written record supports the spoken brief and gives the incoming crew a place to verify it.

Never delay control of the boat to finish a sentence. Record the time or a short prompt, handle the immediate task, then complete the entry honestly when workload permits. Mark anything reconstructed from memory.

Keep the pen or input device with the log so the next entry is easy to make.