The Mercantile Marine Act of 1850 (13 & 14 Vic c 93) transferred all functions relating to seamen and apprentices who were not in the Royal Navy, including the General Register and Record Office of Seamen, which registered merchant seamen by means of a register ticket system, from the Admiralty to the Board of Trade, which thereby inherited the office of Registrar General of Seamen.
The same act established local Shipping Offices, later called Mercantile Marine Offices, where all crews of foreign-going vessels were to be engaged and discharged under formal articles of agreement, a measure that was intended to combat exploitation, and provided for the issue of certificates of competency to masters and mates.
The Merchant Shipping Act of 1854 (17 Vic c 104), which gave 'general superintendence of all matters relating to Merchant Ships' to the Board of Trade and required all British ships to be registered, also gave the General Register Office the duties of keeping 'a Register of all persons who serve in ships subject to the provisions of this act' and preserving the ships' official logs.
In 1857 the registration of seamen was abandoned, as being too expensive and no longer necessary. The development of a professional navy, with the introduction of continuous service for ratings after 1853, and the formation of a Royal Naval Reserve after 1859 meant that the Admiralty no longer required a separate register of merchant seamen, although the Registrar General did co-ordinate the enrolment and payment of training allowances to reservists. From 1857 until 1913, the crew lists, to which no index of names was kept, became the only central record of serving merchant seamen.
The Registrar General of Shipping and Seamen (abbreviated to RSS, below) was formally established by the Merchant Shipping Act of 1872 (35 & 36 Vic c 73), when the Registrar General of Seamen took over responsibility for returns relating to the registration of ships from the Board of Customs' Chief Registrar of Shipping.
Customs officers in each port of registry continued to register ships, issue certificates of registration and record subsequent transactions, sending duplicate entries to the Registrar General. By 1888 RSS had five divisions: Registration of Shipping; Royal Naval Reserve; Masters Mates Engineers and Skippers; Ships Employment and Records.
The Merchant Shipping Act of 1894 reinforced previous legislation and required all British sea fishing boats, irrespective of size, to be registered.
In 1910, the Advisory Committee on Merchant Shipping proposed to the Board of Trade that a Central Index Register of merchant seamen should again be created. A Central Index Register was started in October 1913 and maintained until 1941.
Registration was made compulsory by the Registration of Merchant Seamen Order of September 1918, under the Defence of the Realm Act.
RSS was transferred from the Board of Trade to the Ministry of Shipping in 1939 and to the Ministry's successor, the Ministry of War Transport in 1941. In the same year it moved from London to Cardiff. The Essential Work (Merchant Navy) Order 1941 created a Merchant Navy Reserve Pool. To ensure that seamen would always be available to man vessels, the Government paid them to remain in the Reserve Pool when they were ashore.
Now that continuous paid employment instead of casual employment was available to all seamen, comprehensive and effective registration became possible. All those who had served at sea during the previous five years were required to register with the Registrar General and a new Central Register of Seamen was started. The Central Register of Seamen was maintained until 1972, after which registration effectively ceased.
After 1946, the Merchant Navy Reserve Pool was disbanded. The Royal Naval Reserve was combined with the Royal Naval Volunteer Reserve in 1957. RSS became part of the Marine Crews Division of the Ministry of Transport, moved back to the Board of Trade in 1965 and was absorbed into the Department of Trade and Industry in 1970. In 1975 it moved to the Department of Trade and then in 1984 returned to the Department of Transport.
The simpler Small Ships Register, for craft less than 24 meters length, was introduced in 1983. The register was first run by the Royal Yachting Association; then by the Driver and Vehicle Licencing Centre Swansea and then from 1997 by RSS
In 1992 RSS became part of the Marine Safety Agency; and in 1998 the Marine Safety and Coastguard agencies merged to form the Maritime and Coastguard Agency.
In 1994 a new system of registration for ships was introduced including the requirement to renew every five years, and this was followed in 1997 by computerisation of all vessel registration on the Fleet Management System (FMS).