The modular design allows flexibility in the scope of supply.
A compactly designed axial pump with excellent efficiency, cavitation and noise characteristics.
High performance components in stainless steel to prevent wear and corrosion.
The water lubricated bearing in the stator bowl provides an environmentally friendly solution.
Water lubricated Face type sterntube seal with an optional inflatable emergency seal.
Inboard mounted thrust bearing block, for increased life and easy maintenance.
Tailor-made inlet design based on the shape and operational profile of the vessel.
The characteristics of a waterjet make it a good propulsor for numerous applications.
Examples of such applications include:
For naval architects this creates the possibility to apply a larger power density onto narrower hulls so as to achieve top vessel performance.
Jet sizes are indicated by the front side diameter of the impeller seat ring. Unlike a non-axial design
(Figure left), the Wärtsilä axial design waterjet (Figure right) does not expand in a radial direction downstream.
Waterjet size selection
The selection graphs indicate the jet size required based on the relation between the engine power and the design speed of the vessel. For instance a ship with four 1250 kW engines and a corresponding vessel speed of 33 knots will need four 510 size waterjets. A ship with a design speed of 40 knots at 1250 kW power can use 450 size waterjets. The correct jet size is thus indicated by the line above the intersection of the power and the corresponding vessel speed (see examples in the graphs below).
We are available from the earliest design stages of the vessel to work with you on an optimised propulsion system. Please contact us for an optimised jet selection based on specific vessel design parameters, operating profile or for details of waterjets above 50 knots or 30 000 kW. DXF/DWG format general arrangement drawings of the most often used sizes are available.
Additional design information can be found in the “Waterjets Product guide”, which can be downloaded here.
During operation, water enters the waterjet through the inlet duct, which is part of the ship’s construction. After passing the pump impeller, the rotation in the flow is removed and the water is accelerated in the stator bowl. This creates the thrust necessary to propel the ship. For steerable waterjets, the jet stream is deflected by a jetavator which is mounted behind the stator bowl. The jetavator is actuated by an inboard mounted hydraulic cylinder and can be turned 30° to port and 30° to starboard.
The jetavator contains a hydraulically activated reversing plate through which part or all of the jet stream can be deflected forward. The reversing plate can be gradually moved, which makes it possible to vary the thrust from full ahead via the zero thrust position to full astern and vice versa.
The zero thrust position prevents the ship from moving when the impeller shaft is clutched in. The reverse cylinder is equipped with a counter balance valve (load holding valve). This safety device keeps the reversing plate movement controllable and prevents that, in the event of a hose failure, the reverse plate from moving to full astern without control.
In addition to the main waterjet hardware, Wärtsilä can supply other equipment that can be integrated as part of the Wärtsilä solution.
If needed, the hydraulics can be customized to include, for instance, additional functionality.
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Wärtsilä is a global leader in advanced technologies and complete lifecycle solutions for the marine and energy markets. By emphasising sustainable innovation and total efficiency, Wärtsilä maximises the environmental and economic performance of the vessels and power plants of its customers.