Question

how do ocean currents facilitate the movement of ships?

Answer 1

Ocean currents facilitate the movement of ship as the waves goes up and down due to gravitational pull , when that happens a push is given to the down part of the ship which helps it move forward.

Answer 2

The rare instances where ocean currents helps the ship is when there is strong current pushing the vessel from aft in the direction the vessel is proceeding. This means there is an external force pushing the vessel ahead apart from the propelling force exerted by the engine through the propellers. So this added extra force increases the speed of the vessel, thus helping the vessel cover more distance than usual. Thus the average fuel consumed for covering the given distance gets reduced. In this condition, the vessel has acquired negative slip.