A spar buoy is a tall, thin buoy that floats upright in the water and is characterized by a small water plane area and a large mass.
Because they tend to be stable ocean platforms, spar buoys are popular for making oceanographic measurements.
Adjustment of the water plane area and the mass allows spar buoys to be tuned so they tend to not respond to wave forcing.
[4] Spar buoys range in length from around one metre[5] to the 108-metre (354-foot) RP FLIP.
To avoid the difficulties inherent with shipboard launch and recovery, helicopter deployment of large spar buoys has been studied.