Were early petrol or diesel engines advanced enough for proper Royal Marine landing craft?
Short answerProbably, but the 1916 generation is more convincing than 1912; power was available, while reliability and noise were the main practical drawbacks.
NotesEngine power is only one part of amphibious design. Early petrol and diesel units could probably move a purpose-built landing craft, so raw power was not the decisive obstacle. Reliability and the extraordinary noise of the machinery would shape how safely and effectively the craft could approach a shore. The more mature engines available by 1916, including developments driven by aviation, make the concept more credible than the technology of 1912.