Final answer:
A jet-driven watercraft without power becomes unmaneuverable and would stop due to the absence of propulsion. Alternative methods of propulsion, although theorized, face practical challenges and drawbacks in actual marine environments.
Step-by-step explanation:
Without power, a jet-driven watercraft would become unmaneuverable and eventually come to a stop due to the lack of thrust provided by the jet propulsion system. Jet watercraft operate by expelling water through a jet propulsion system, and without a source of power, this system cannot function. Comparable to the fictional Red October's magnetohydrodynamic drive, which requires high magnetic fields or electric currents, a jet-driven watercraft requires its engines to generate thrust. Without power, the natural resistance of the water combined with other forces such as drag and gravity would bring the watercraft to a halt.
In naval engineering, alternative propulsion systems, like the magnetohydrodynamic drive, face significant challenges, including high noise levels due to electrolysis bubbles, detectable chemical trails, and corrosion of metal parts. These issues make such systems impractical compared to more conventional methods like nuclear-powered turbines or electric generators as depicted in conventional marine transportation.