What was the last warship laid down that served with vertical triple-expansion propulsion?
Short answerProbably a Second World War frigate such as a River-class ship, although the precise ship and expansion-engine terminology remain qualified.
NotesA Second World War frigate, possibly a River-class ship, is the tentative candidate for the last warship laid down with reciprocating expansion machinery. The precise identification remains uncertain. The machinery terminology also needs qualification: late quadruple or multistage expansion engines differ from VTE, meaning vertical triple expansion.