A Seaman’s Book is a full record of a seaman's career experience and certifications. Every seafarer must carry this document while on board, which is also an official and legal record of his sea experience. The Seaman’s Book is one of the compulsory documents for applying crew transit visas; it certifies that the person holding it, is a Seaman as per The International Convention on Standards of Training, Certification and Watch keeping for Seafarers (STCW) and all records of employment on board of a merchant ship (sea service) is recorded in the Seaman Service Book.
The Seaman's Book also provides a travel document that can be used with a passport and, in some cases, in lieu of a passport. But the big advantage point of having a Seaman's Book, comes when it is presented by an individual who would ordinarily require a visa to enter in a foreign country. If the Seaman can show that he is joining or leaving a vessel, then the border official can waive the visa requirement to enter that country. This would work in the countries that are signatory to the International Labour Organization (ILO) Convention 108, and in limited circumstances, to the ILO No. 185.