What a discharge book is (where it is separate from the CDC), how it records sea service, and what to do if endorsements are missing.
What it is
In most maritime nations the discharge book is the same document as the CDC / Seaman's Identity Document — the section of the booklet that records each sign-on and sign-off endorsement signed by the Master. In a few jurisdictions (e.g. the United Kingdom's MCA Discharge Book, the United States' Merchant Mariner's Document predecessor system) the discharge book is a stand-alone document separate from the seafarer identity card.
Who needs it
Every seafarer on a commercial vessel — the discharge endorsement is the primary evidence of sea time used for CoC issue, revalidation, and rank progression.
When it is checked
Sign-off — the Master signs and stamps the discharge endorsement.
CoC / CoP application + revalidation.
Manning-agency intake (your sea-time history is evaluated from the endorsements).
STCW Regulation A-I/2 record verification by some flag states.
Common mistakes
Sign-off endorsement missing or unsigned — without it the contract cannot be counted toward STCW sea time.
Sea-time record not transferred when migrating to a new CDC.
Discrepancy between the discharge endorsement and the SEA — rank, contract dates, or capacity must match.
Sending the original to a recruiter for review — never let an unverified agency hold it.
Validity
The book itself has the same validity as the CDC / SID. Endorsements within it are permanent records of completed service.
If lost or expired
Treat as a lost CDC: police report, application to the issuing administration, fee, photographs, original passport. Lost sea-service records can sometimes be reconstructed from your SEA copies, P&I records, and the previous owner's crew list — keep copies of every SEA you sign.
Printable checklist
Discharge book / CDC in hand.
All prior sign-off endorsements signed and stamped.
Sign-on and sign-off dates legible and consistent with the SEA.
Rank capacity matches what you signed for.
Photocopy + phone-photo backup of the last five endorsements.