Spar buoy
Encyclopedia
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. This characteristic differentiates them from large water plane area buoys such as discus buoys that tend to be wave followers. Spar buoys are often used as stable platforms for wave measurement devices (c) and air sea interaction measurements (d), Spar buoys range in length from a few feet (e) to over 100 feet long. To avoid the difficulties inherent with shipboard launch and recovery large spar buoys may be deployed by helicopter
(f).
A Woods Hole Oceanographic Institution
report ( http://hdl.handle.net/1912/1552 ) describes a computer solution to help predict the heave and roll response of free floating bodies of cylindrical shape when excited by random seas with known spectra. The analysis presented in this report may be used to predict the motion of spar buoys. The basic concepts of harmonic analysis
and statistics used in the method are first briefly reviewed. The report then presents a detailed derivation of the linear heave and roll response amplitude operators, that is the expressions of the vertical and angular displacements produced by a simple harmonic wave of one foot amplitude. The second part of the report reviews the computation procedure and the program's logic. The report presents a method to make linear the non linear ( velocity squared) drag forces by equating the energy dissipated over one cycle by non linear drag to a linearized drag term. For the linear solution superposition is valid and the heave and roll amplitude operators may be computed for various sea states.
Buoy
A buoy is a floating device that can have many different purposes. It can be anchored or allowed to drift. The word, of Old French or Middle Dutch origin, is now most commonly in UK English, although some orthoepists have traditionally prescribed the pronunciation...
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
Oceanography
Oceanography , also called oceanology or marine science, is the branch of Earth science that studies the ocean...
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. This characteristic differentiates them from large water plane area buoys such as discus buoys that tend to be wave followers. Spar buoys are often used as stable platforms for wave measurement devices (c) and air sea interaction measurements (d), Spar buoys range in length from a few feet (e) to over 100 feet long. To avoid the difficulties inherent with shipboard launch and recovery large spar buoys may be deployed by helicopter
Helicopter
A helicopter is a type of rotorcraft in which lift and thrust are supplied by one or more engine-driven rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forwards, backwards, and laterally...
(f).
A Woods Hole Oceanographic Institution
Woods Hole Oceanographic Institution
The Woods Hole Oceanographic Institution is a private, nonprofit research and higher education facility dedicated to the study of all aspects of marine science and engineering and to the education of marine researchers. Established in 1930, it is the largest independent oceanographic research...
report ( http://hdl.handle.net/1912/1552 ) describes a computer solution to help predict the heave and roll response of free floating bodies of cylindrical shape when excited by random seas with known spectra. The analysis presented in this report may be used to predict the motion of spar buoys. The basic concepts of harmonic analysis
Harmonic analysis
Harmonic analysis is the branch of mathematics that studies the representation of functions or signals as the superposition of basic waves. It investigates and generalizes the notions of Fourier series and Fourier transforms...
and statistics used in the method are first briefly reviewed. The report then presents a detailed derivation of the linear heave and roll response amplitude operators, that is the expressions of the vertical and angular displacements produced by a simple harmonic wave of one foot amplitude. The second part of the report reviews the computation procedure and the program's logic. The report presents a method to make linear the non linear ( velocity squared) drag forces by equating the energy dissipated over one cycle by non linear drag to a linearized drag term. For the linear solution superposition is valid and the heave and roll amplitude operators may be computed for various sea states.