 <unk> buoys are round and moored in deep ocean locations , with a diameter of 10 metres ( 33 ft ) to 12 metres ( 39 ft ) . The aluminum 3 @-@ metre ( 10 ft ) buoy is a very rugged meteorological ocean platform that has long term <unk> . The expected service life of the 3 @-@ metre ( 10 ft ) platform is in excess of 20 years and properly maintained , these buoys have not been retired due to corrosion . The NOMAD is a unique moored aluminum environmental monitoring buoy designed for deployments in extreme conditions near the coast and across the Great Lakes . <unk> moored off the Atlantic Canadian coast commonly experience winter storms with maximum wave heights approaching 20 metres ( 66 ft ) into the Gulf of Maine . 
