washboard: protective covering consisting of a broad plank along a gunwale to keep water from splashing over the side
protective covering: a covering that is intend to protect from damage or injury
rosidae: a group of trees and shrubs and herbs mostly with polypetalous flowers; contains 108 families including Rosaceae; Crassulaceae; Myrtaceae; Melastomaceae; Euphorbiaceae; Umbelliferae