Get to know the basics

Bow thrusters and stern thrusters are a type of propeller-driven system, similar to a boat motor’s propeller, but smaller in size, and placed in the bow or stern to help the captain manoeuvre the vessel at slower speeds. Thrusters come in handy, particularly when docking and moving in tight spaces. Having both a bow and stern thruster allows the boat to move independently of its normal motor(s) and move in a sideways motion without moving in reverse or a forward direction under power at the same time. 

Bow thrusters and stern thruster are both placed in through-and-through tunnels, in other words, both sides of the tunnel are open allowing one side to create suction and throw it out the other, depending on which direction the captain is wanting the boat to move in. When the boat is under power an air pocket forms around the bow thruster tunnel opening. When cruising at higher speeds the thruster and tunnel are out of the water. This design ensures no power is lost when travelling at any speed.