A riser centralizer for transferring lateral loads from the riser to a platform hull includes a keel centralizer mounted on a keel joint. The keel centralizer is received within a keel guide sleeve secured in a support mounted at the lower end of the platform hull. The keel centralizer includes a nonmetallic composite bearing ring having a radiused peripheral profile for minimizing contact stresses between the keel centralizer and the keel guide sleeve in extremes of riser and platform motion. The internal surface of the keel guide sleeve is clad with a corrosion resistant alloy and coated with a wear resistant ceramic rich coating.