Question

what are the different ways to increase and decrease friction in ships,aeroplanes and trains

Answer 1

For ships: injecting air bubbles in the boundary layer, the use of air films along the bottom
plating, and using air cavities in the ship's bottom.

For aircrafts: The shape of the aircraft is build in such order to reduce drag so that fluid can flow past easily and smoothly, without any swirls This tends to mean using long, pointed, "streamlined" shapes.

For trains: use of ball bearings, lubricants, electromagnets