D. G. Gryazin
Saint-Petersburg State Institute of Fine Mechanics and Optics (Technical University)
The most wide-spread facilities
of sea chop features measurement are the wave-tracking buoys. These instruments
are installed on water areas of seas and oceans and send data by the radio.
Measurement results obtained with these instruments contain not only instrumental
errors but truncation errors as well. One of such errors is an error caused
by the buoy vertical rolling. By the vertical rolling we mean buoy fluctuations
in vertical direction with regard to the wave surface.
For amplitude-frequency characteristic calculation
of vertical rolling the differential equation of the second order is used.
One component of this equation is the joined mass of water at buoy vertical
fluctuations.
The value of joined mass can be taken from hydrodynamics
reference books but it should be refined. To make the reference data more
precise an experiment in the pool was conducted on the definition of joined
mass value of different buoy types. Obtained values were compared with
data from the reference books and this has allowed us to correct the reference
data.
On the base of obtained values of joined masses
the calculation of buoy vertical rolling was made. Calculation results
were compared with the experimental characteristic of vertical rolling
obtained in the pool.
The comparison of experimental and calculated
curves gives good results. Based on the results of the work it is possible
to recommend the obtained values of joined masses for using in calculations.