The study of joined water mass values of a wave-tracking heaving buoy

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.