pumpjetsystem

A pumpjet system, also known as a waterjet propulsion system, is a type of marine propulsion that uses a pump to draw water into an intake and expel it at high velocity through a nozzle. This expulsion of water generates thrust, propelling the vessel forward. Unlike conventional propellers, pumpjets are fully submerged within a duct or shroud, which can offer several advantages.

The primary components of a pumpjet system include an intake, a pump (often an impeller or axial flow pump), a duct or shroud, and a nozzle. The intake is positioned to efficiently draw water into the system. The pump then accelerates this water. The duct or shroud helps to direct the water flow and can also improve efficiency and reduce cavitation. Finally, the nozzle shapes the exiting water stream to maximize thrust.

Pumpjets are known for their maneuverability, especially at low speeds, as the direction of the water jet can often be controlled with steering vanes or by vectoring the nozzle. They also tend to be quieter and produce less vibration than open propellers, making them suitable for applications where stealth or comfort is important. Additionally, the submerged impeller reduces the risk of damage from debris or grounding compared to exposed propellers.

Applications for pumpjet systems range from high-speed ferries and patrol boats to yachts and some military vessels. They are particularly effective in shallow waters where propeller clearance is limited. The design of the pumpjet can be optimized for different operating conditions, balancing efficiency, speed, and maneuverability.