Yesterday morning our mooring spot was being buffeted by the waters rushing out of the weir. Even though the battery was quite well charged, I started the diesel engine before we set off. Switching between electric drive and diesel drive is as simple as stopping or starting the engine, if the engine is warm, starting is as simple as turning the key. But starting the engine from cold requires putting high revs on in neutral, pre-warming the engine for five or ten seconds, and then starting it. Not something to do in response to realising that the current is too strong.