Evictor, Anti-Piracy Water Cannon

The Knowsley SK ‘Evictor’, Anti-Piracy Water Cannon is an essential part of the multi-layered approach to ship hardening. Utilizing the ships existing fire main or high capacity water supply the Evictor nozzles provide a powerful jet of water and a water mist, to create an effective water shield with tremendous visual presence, inhospitable atmosphere and a physical force capable of deterring the most determined of pirate.

How does it work?

The Evictor was designed and developed based on the long established Knowsley SK self-oscillating monitor. Utilizing the ships fire main or any other high capacity water supply, the Evictor directs a jet of water along the ships stern and the twin nozzles oscillate in an arc to provide an effective water shield.

The powerful water jets act as a visual deterrent to any approaching vessel.  Once in close proximity, the volume of water can quickly overwhelm a small boat below and the water spray creates an unhospitable environment and a physical force capable of dissuading even the most determined pirate.



The Evictor uses a standard Knowsley SK bronze Pelton wheel, which takes firewater feed from the monitor inlet stand driving the oscillation.  The Pelton wheel is very effective using as little as 25lpm of fire water at 7 bar g. A Y-type strainer with flushing valve is fitted to prevent blockage of the Pelton wheel water feed nozzle to ensure years of service.

Material selection is of vital importance in marine environments, the Evictor is constructed from corrosion resistant materials with this in mind.

+ Monitor Body: Gunmetal to BSEN 1982 CC492K-GS
+ Pelton Wheel & Gearbox: Bronze
+ Accessories: 316 Stainless steel


The Evictor is available in two flow capacities, with the base monitor and frame common to both units.  The nozzles are interchangeable and available in either High Flow (Table 1) or Medium Flow (Table 2) options.  The nozzles are easily interchangeable providing future flexibility if the Evictor is moved to a different vessel with a higher or lower water supply.

  • Product group Special
  • Material Carbon Steel, Hot Dip Galvanized And Enamel Coated
  • Colour Yellow
  • Dimensions 1195 x 550 x 400
  • Length nozzle extension 817mm
  • Inlet Connection 2 ½” BS336 Instantaneous Male Connection
  • Oscillation speed 7 cycles per minute at 7 bar g
  • Nozzle angle 70 degrees
  • Min. operating pressure 5 bar g
  • Max. operating pressure 13,5 bar g

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