Abstract: A separation and guidance structure comprises an arm having an inner end with a crosspiece secured in use to a pontoon or the like, and an outer end provided with fenders extending above and beyond the end of the arm. Flotation is provided to support the outer end of the arm, and may be in the form of a flotation member or be provided by the fenders. In use a number of such structures are secured in parallel to a pontoon or dock to form a berthing system.