A flow extender is a hydrodynamic improvement to increase the propulsive efficiency of a vessel. This is done by placing a nozzle around the propeller which extends the outflow of the water. The flow extender causes the radial water flows to be directed towards the back of the vessel. The higher outflow velocity of the propeller that is obtained leads to more effective propulsion as higher thrust is delivered at the same level of engine power. This technology increases the propulsive efficiency to increase up to 15%, which reduces fuel costs and emissions.