It makes manoeuvring easier, safer and quicker. The propeller, which is made of maintenance free synthetic material, can run in two directions, thus producing a jet flow to port or starboard. Each propeller is designed to achieve maximum thrust in a small tunnel diameter. This makes manoeuvring in tight spots against a strong current or a shifty wind much easier.
Craftsman Marine specifies the average force of the thrusters, however the starting peak force (1 second) can be easily 60% higher.