New Scientist The Pursuit Marine Drive produces thrust by using the energy from high-pressure steam to draw in water through an intake at the front and expel it at high speed through the rear. The steam emerges at high speed from a rearward-facing ring-shaped nozzle into a cone-shaped chamber, where it mixes with the water (see graphic). Shock waves created as the steam condenses are focused by the chamber to blast water out of the back.