The T.I.D. class tug was designed to quickly and cheaply replace tugs
lost through enemy action during World War II. Suitable vessels were also
needed to support the preparations for the invasion of France.
The origin of the 'TID' abbreviation remains uncertain with interpretations varying from; 'Tug Invasion Duty' to 'Tug in Dock' to 'Tug Intermediate Design' to 'Tiddler'.
Specification and design started in 1941 and the first TID was launched in 1943.
Richard Dunston Ltd of Thorne and Hessle - Yorkshire produced a design
with dimensions of:
Dunston's design was for an all welded hull with a hard chine so that flat plates could be used to speed production and for ease of manufacture.
The hull was designed to be made in sections by engineering firms away from the coast and transported to a shipyard for assembly. The sections were eight in number to allow for road transportation. The sections were a maximum 10 ft long by 17 ft wide by 13 ft deep and weighed a maximum of 6 tons.
The coal burning T.I.D's had a bunker capacity of about eight tons and the oil burning ones about nine tons. Approximately 120 coal fired vessels were built and 60 oil fired units.