Indeed, the siren on police boats has a place. How nice that it is very easy to implement, we need next actions:
- in CfgVehicles → Boat_Civil_01_base_F → Sounds add this code see Pastebin
- in CfgVehicles → Boat_Civil_01_base_F → UserActions add this code see Pastebin
Look at the result - https://youtu.be/Z3Sr42D0J1g, same as @madpat3 requested via video