OCSNCOE Unit Emblem (silhouettes of a self-elevating MODU, an OSV and an offshore wind turbine over a silhouette of the United States with the U.S. Coast Guard mark (i.e., racing stripe) in the background).Outer Continental Shelf National Center of Expertise (OCSNCOE)

JACK ST. MALO during offshore construction with attending OSV and Floatel VICTORY. C-ENFORCER underway with water cannons flowing. SEVAN LOUISIANA underway when initially entering the U.S. Gulf of Mexico. Platform GINA off the California coast. Block Island windfarm with attending CTV. SPARTAN 151 dockside in Seward, AK.



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The Drill Down, Issue #14: Vessel Logbooks

Graphic of a drill stringIntroduction

A ship's logbook has been an essential part of a vessel dating back to antiquity. Used to log everything from voyages, stores, and crew, a ship's logbook or record reliably documents the goings-on of a ship and has remained fundamentally unchanged for years. Now a legal requirement, logs, and records are recorded in either an Official Logbook or an unofficial record or logbook.

But what is the difference between an Official Logbook and an unofficial log or record? And what are the requirements for an Official Logbook?

This issue of Drill Down explains Official Logbooks for OSVs, when they are required, and when an unofficial logbook is suitable for record-keeping.

What is an Official Logbook?Official logbook Cover

An Official Logbook (CG-706B/C) is a legal document required for U.S. vessels on a voyage from a port in the United States to a foreign port; or vessels of at least 100 gross tons and on a voyage between a U.S. port on the Atlantic Ocean and a U.S. port on the Pacific Ocean. The requirement does not apply to a vessel on a voyage from a port in the U.S. to a port in Canada.

The Official Logbook serves as a means to verify vessel employment and wages, and for the USCG to verify compliance with laws and regulations concerning vessel operations and safety procedures.

Items recorded include, but are not limited to, vessel & crew information (including deaths and disciplinary action), watertight integrity, drills, and inspections. The Official Logbook provides instructions to the vessel master for completion.

The Master must make all entries in an Official Logbook. Entries should be made in ink and plain language using accepted nautical terms. The Master and one other crewmember must sign each entry.

There is no electronic version of the Official Logbook.

The Official Logbooks, which are supplied by the U.S. Coast Guard, shall be returned to the OCMI, at or nearest the port where the vessel may be, at the end of the voyage, or after a specified elapsed time (see note).

An Official Logbook is a standard item for traditional shipping, but not something typically found on Offshore Supply Vessels due to the nature of their work and the area in which they operate.

Note: "Elapsed time" is not defined by law; the operator and the cognizant OCMI should arrange the time. Completed Official Logbooks should not be forwarded to USCG Headquarters or the National Maritime Center.

OSV Logbooks and Records

OSVs are required by regulation (46CFR § 131.610) to have a logbook or record. If an Official logbook is not required, then an unofficial log or record must be used.

Subchapter L regulations (46CFR § 131.620) specify what must be entered in the logbook, e.g., drills, draft & loading marks, stability, and departure checks. Titles 33 and 46 CFR contain regulations that require additional log entries to be made.

Unofficial logs are typically kept in a journal or notebook but may be kept electronically.

Unofficial logbooks are not filed with the OCMI but must be kept available for review by a CG Marine Inspector for at least one year after the date of the last entry.

There are no regulatory requirements for signatures on unofficial logs or records.


Logs and records are critically important documents and comprise a legal record of a vessel's activities. 

U.S. flagged vessels are required to keep either an Official Logbook or an unofficial logbook per the vessel's applicable Subchapter.

All entries should be factual, precise, legible, and entered promptly. 

For additional information regarding Official Logbook requirements, please see the excerpt below:

Official Logbook Instructions