Keeping a Ship’s Log: Essential for Safe and Effective Vessel Management

Keeping an accurate ship’s log is an essential part of safe and effective vessel management. Not only is it a legal requirement for all boats when at sea, but it also helps the skipper monitor weather conditions, vessel systems, and navigation progress. Whether you’re preparing for your RYA Day Skipper course or planning a Malta sailing adventure, understanding what to record in your log is crucial.

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⛵ Why Keep a Ship’s Log?

A properly maintained log allows a skipper to:

        • Track and predict weather and sea conditions

        • Monitor the vessel’s systems and resources, including crew welfare

        • Serve as a reliable navigation aid and official record of the voyage

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🌊 Essential Information to Record in Your Ship’s Log

No matter which type of logbook or digital system you use, there are key details every log should contain, recorded consistently—ideally every hour on the hour:

        • Date

        • Vessel Details: Name, MMSI number, and call sign

        • Number of persons onboard

        • Time of each entry: Specify if local time, ship’s time, or Universal Time (UT)

        • Departure and destination ports, including high water (HW) and low water (LW) times and tidal heights

        • Water log (odometer for distance travelled)

        • Water speed (log speed)

        • Heading: Indicate whether true, magnetic, or compass heading

        • Leeway: Estimated sideways drift, recorded periodically

        • Position fix: Derived from GPS, visual fixes, or buoyage

        • Current sail plan: What sails are set and reefed

        • True wind speed and direction

        • Apparent wind speed and direction

        • Visibility conditions

        • Sea state: Wave height and condition

        • Cloud cover: Noted as fractions (e.g., 5/8 cloud cover)

        • Barometric pressure

        • Weather forecasts received

        • Battery charge levels

        • Fuel tank status

        • Bilge condition check

        • Water tank status

        • Comments: Notes such as “4 miles south of Portland Bill, 3 hours favorable tide, port watch on deck, next watch change at 0200 UT, all good.”

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📍 Why This Level of Detail Matters

Recording this information regularly helps the skipper maintain full awareness of changing conditions and vessel performance, even when resting or off-watch. The skipper can leave specific instructions for the crew such as:

“Wake me if wind speed increases by more than 4 knots, wind direction changes by over 15°, cloud cover reaches 6/8, visibility drops below 2 miles, a vessel is sighted within 5 miles, or if unsure.”

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🛠 Additional Logs for Long Passages

On extended voyages, it's also vital to record:

        • Times when water tanks are refilled or changed

        • Engine, generator, battery charger, and watermaker running hours

        • Regular ocean weather report checks and satcom contacts

        • Separate defect and repair logs

        • Crew health and medical records

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🌍 In Summary

Whether you’re cruising around Malta, preparing for the Yachtmaster exam, or embarking on a sailing charter in the Med, a detailed and consistent ship’s log is your best tool for safe navigation and voyage management. Keeping a good log isn’t just about ticking boxes—it’s about protecting your vessel, your crew, and your journey at sea.