How to search the records
The National Archives hold microfiche copies of the registration cards for merchant seamen issued by the Board of Trade and falling into three types of record cards called CR1, CR2 and CR10.”CR” stood for central registry. BT350 is equivalent to CR10 refers to seamen in the period 1918 to 1921 and is alphabetical and has photographs. BT349 is an index equivalent to CR1 and is an alphabetical index for the period 1921 to 1941. Take note of the discharge number and use this to search the numeric index BT348 which will give you further information. There is also an additional series, BT 364 which is an index available in microform at the National Archives and appears to refer to seamen who went on to serve in World War Two amongst others. Their card will have been removed from the earlier BT 348, 349 and 350 series so look here if they cannot be found in the main series. Fortunately you can search the combined BT 348, BT 349 and BT 350 series at findmypast.com: http://www.findmypast.co.uk/search/merchant-navy-seamen12 June 2024 Finding Merchant Seamen Ancestors
What are the Merchant Seamen Registration cards?
In 1910 the Government’s Advisory Committee on Merchant Shipping recommended that a new Central Register of Seamen should be created and so the Fourth Register of merchant seamen was started in 1913. These records are in effect a resumption of the records of the Third Register which was discontinued in 1857. Although begun in 1913, the registry cards for first few years of this record series were destroyed and they were discontinued in 1941, so the actual run of records is for those seamen engaged between 1918 and 1940.
There are very nearly 1 million cards representing around 400, 000 individuals who served on British Merchant vessels between the two World Wars. The originals are held by the Southampton City Archives. They represent a relatively recent, but important group of mariners for the period 1918 to 1940. They have become part of the National Archives collection and are in the main held as series BT 348, 349, and 350.