An assembly for mounting components on a vessel having a boss with an adapter and a method of attaching. In one embodiment, the assembly includes an adjustable frame including a support positioned between a first end and a second end, a fixed clamping device attached to the first end of the frame and including a lower plate and pivotally attached upper plate such that at least one of the lower and upper plates has a shaped jaw formed therein to hold a first adapter. The assembly further includes a rotatable clamping device made up of a lower clamping plate along with a lower plate rotatably attached to the lower clamping plate, and an upper plate pivotally attached to the lower plate. At least one of the lower and upper plates have a jaw formed therein to hold a second adapter.