Names of the parts on board sea going tugs used for fire fighting . Specially the nozzles on the mondey deck?

Question

Explain the fire fighting nozzle fitted on the monkey deck on sea going tugs which can move vertically and horizantally with a hydraulic motor.

Answer 1

Water cannons, sometimes known as monitors.  No, I've no idea why:-)

Mostly found on specialist salvage or rescue vessels, for obvious reasons

Answer 2

What is there to explain, they pump sea water through the nozzles for fighting fires, plain and siimple.