13.1.1 Dredgers
                                 designed to work in conjunction with hopper barges are to be fitted
                                 with permanent rubbing strakes or fenders extending down to their
                                 lowest normal operating waterline. On transversely framed vessels
                                 it is recommended that the side structure in way of the lower edge
                                 of the fender be reinforced by a stringer and/or cross-ties. It is
                                 recommended that, where wooden fenders are fitted to dredgers operating
                                 in tropical sea-water, the fenders be cut just above the deepest working
                                 waterline and a gap be left sufficient to prevent water soaking up
                                 into the fenders.