Thanks to all the suggestions
Glad you found it but Dang, would sure like to know how it was wired to cause the problem
Had to trace the siren wires back pretty much undo clamps on massiveblock wires behind the dash. Was looped into the fuse panel with an extra fuse inline. Then trace wires back to the rear of boat.
Which was connected to float switch
Cut wires there siren stopped
Bilge float switch replaced and worked perfect.
was just coincidence that i had all work done on motor the same time the switch decided to give up
Lucky I had a great elect troubleshooter stay for a few days and sorted the issue