There are two types of ships, submarines and targets.

studebaker hoch: devine: From the wiki on the Virginia class subs

In contrast to a traditional bladed propeller, the Virginia class uses pump-jet propulsors


Huh. Evidently they have been doing this for a while.

/just reread Hunt for Red October a couple weeks ago

Tom Clancy always seemed just a little too smart to just be making stuff up.

The Virginias use something different than what the Red October had in the book and the movie.  A pump-jet is the same kind of propulsion system jet-skis have (just really big in this case), the "caterpillar drive" in "Red October" was a magnetohydrodynamic drive (MHD).

As Clancy said, MHD's are really quiet because they don't have moving parts.  From Wiki: It "is a method for propelling vehicles using only electric and magnetic fields with no moving parts, accelerating an electrically conductive propellant (liquid or gas) with magnetohydrodynamics. The fluid is directed to the rear and as a reaction, the vehicle accelerates forward "  Pump-jets have a number of moving parts, but are quieter than propellers.

While a couple large scale MHD prototype vessels have been built, it's never been used on an operational vessel, military or civilian.  Again from Wiki:  "Few large-scale working prototypes have been built, as marine MHD propulsion remains impractical due to its low efficiency, limited by the low electrical conductivity of seawater. Increasing current density is limited by Joule heating and water electrolysis in the vicinity of electrodes, and increasing the magnetic field strength is limited by the cost, size and weight (as well as technological limitations) of electromagnets and the power available to feed them."