Why did the Royal Fleet Auxiliary build so few dedicated colliers before the First World War?
Short answerMost coal moved from base to base in hired merchant ships and was loaded in harbor; dedicated auxiliaries were chiefly needed for forward or high-risk supply.
NotesRoyal Navy ships normally took on coal in harbor or at a base, so much of the supply task was moving bulk fuel between established facilities. Britain's large merchant marine could provide hired ships for this work. Dedicated RFA colliers were chiefly useful for forward positions or places where the risk made an ordinary charter less suitable. The smaller American merchant marine made hiring equivalent transport harder, and the US Navy sometimes hired British merchant ships.