We've spotted the pirate vessel and positively confirmed its identity. You could use the 7.62mm machine guns on your RHIBs to engage the pirate vessel, however weapons of this caliber are unlikely to cause significant damage to a ship and their short range exposes your units to return fire.

Select your patrol boat, press F1 to order an automatic attack and then click on the pirate vessel. Your patrol boat will automatically move towards the pirate vessel and engage when it comes into weapons range.

You can leave your helicopter or boats in the vicinity of the pirate vessel to track their position while waiting for the patrol boat to close, or order them to return to the patrol boat by pressing the B key. If you lose sensor contact with the pirate vessel you will need to re-locate it before engaging.