After cutting his clothing free from the propeller, he pulled Charlie back into the boat and performed mouth-to-mouth resuscitation.

BBC: Charlie Hutton's propeller death accidental

Unlike the blades on old-fashioned propeller engines, these blades spin around at the back of the engine.

ECONOMIST: Monitor

But the Rolls-Royce Azipull has the propeller at the front of the pod rather than the back.

ECONOMIST: Marine technology: A voyage of discovery | The