BGA...if you have to find a new place to mount your antenna (s), may I suggest...if it will fit there, mount it just outside where the Bimini's main rail mounts to the top of the gunwale...that way you are not ADDING a new obstruction point as you would if say it was mounted in front or behind the top.
Does your Bimini mount top of the gunwale or inside?...there may not be enough room for this if it is top mounted...good luck whatever route you decide to take...and of course PICTURES
