A multi-purpose support plate for use with a boating accessory assembly is disclosed including a first mounting end portion having a first strengthening rib, a center portion having a top layer and a bottom layer, and a second mounting end portion having a second strengthening rib. The first and second mounting end portions include a first or second thickened mounting area, respectively, from which the first or second strengthening rib extends to the top and bottom layers. The center portion of the support plate further includes a center bore. The center bore passes through the top layer and bottom layer to accommodate at least one boating accessory.