A multi-purpose support plate for use with a boating accessory assembly is disclosed. The multi-purpose support plate includes a first mounting end portion having a first clamping region, a center portion having a top layer, a bottom layer, and a central bore, a second mounting end portion having a second clamping region positioned opposite said first mounting end portion, wherein the first and second clamping regions are in removable engagement with an accessory clamp operatively engaged to a boating structure. The first and second clamping regions are affixed to a boat structure by at least one accessory clamp assembly, the accessory clamp assembly being constructed to fit the mounting end portions at their respective clamping regions by frictional engagement.