Regarding, perhaps, a slightly niche area of shipping, recently came across an excellent web site pertaining to vessels attached the Royal Fleet Auxiliary Service (RFA) 1905 -> : whilst not the home page : see below for that : this page is a fine example of the material included on this web site, including vessels in service prior to being taken into the RFA service : http://www.historicalrfa.org/ships-starting-with-r http://www.historicalrfa.org And, whilst probably another niche area, also including RN vessels, but also including many of the more difficult small vessels to track down, from trawlers, drifters, etc. hired by the Admiralty, along with vessels in harbour service and colliers etc. providing fleet services etc: http://www.naval-history.net/WW1NavyBritishShips-Dittmar1.htm and along with these, one shouldn't forget the Navy Lists for pre WWI and WWII and post the end of these wars, which include some vessels not even included in the Naval History Net, which are available from : https://archive.org/search.php?query=Navy%20List The Navy Lists didn't include vessels in the Navy List once the Admiralty realised the value of these books to the enemy during war time ! Paul