corrosion resistant metal and provides not only a ballast weight but also a wear resistant guide for therope in fig6 b a ballast weight 48 is shown which is formed in two halves which can be fitted onto the lower end of the buoy having a groove to accommodate flange 18a at this lower end the two halves are held together by an encircling ring 49 which may be clamp such as a pipe clamp or an extensible band such as a rubber band it is anticipated that the casing and reel parts will be formed in normal production by rotational moulding or blow moulding as an alternative to air inflation the reel when positioned in the casing may be inflated byinjection of a plastic foam this would become hardened in use and prevent disassembly of the buoy there may be a need to limit the axial expansion of the reel during inflation so that it does not expand axially beyond the required limits thus preventing proper rotation in the casing over extension in this manner can be prevented by providing flexible elements internally of the reel these may be formed integrally with the reel material by conducting the blow moulding when the material is in a.