Ships that are propelled magnetically by ionizing sea-water between two electrodes in a magnetic field have been built.
However building a ship with a spiral helix barrel within what the sea-water is ionized and accelerated could contain the electric currents mostly to within the barrel.
When the magnetic field is applied to the electrically polarized sea-water it would spin the spiral helix turbine providing thrust of considerable magnitude because it's would give it a fly-wheel effect that not only would push water but draw it in from the front.
The volume of water within the barrel of the spiral helix turbine would be immense and the angular momentum of the sea-water low could be focused/harnessed to enhance the speed of the Ocean-liner/Naval-ship.
The outlet nozzle could be swiveled to permit/enable fast turning circles and powerful acceleration that isn't restricted by the so-called `forward speed of the propeller'.