Those CG RIB boats with the 50 caliber guns mounted on the bow seem to be all over the NYC waterways. Another spot to be especially careful is in the East River near the UN. I was once 'escorted' through that area by a CG RIB. They did not want to speak on the VHF
either but they left us alone once we had cleared whatever perimeter they were maintaining. I'm not sure who was visiting the UN that day.
Did you leave your Bimini up on your boat?