ABSTRACT 



A disposable telemetering wave buoy is described. Its 

 operating principles, based on measurement of the apparent 

 vertical acceleration of surface water particles, are 

 discussed. The method of reduction of acceleration records 

 to wave height spectra is given. Experiments made in the model 

 tank and at sea, for the purpose of comparing the SPLASHNIK 

 with fairly reliable systems of wave measurement, are 

 described in detail. The results are shown to indicate good 

 agreement between the measurements of the SPLASHNIK and two 

 other instruments. The SPLASHNIK is judged to be acceptable 

 as a wave measurement device, within the scope of its intended 

 use. Future plans for refining the system's accuracy and 

 extending its potential to measurement of other variables are 

 discussed. 



INTRODUCTION 



In connection with full-scale ship trials, it is often necessary to 

 have a description of the state of the sea which may be used as a scale 

 against which to measure ship performance. Visual observations of waves 

 have proven to be unreliable in the past and are, in any event, not 

 sufficiently detailed to be adequately descriptive, for many problems. 

 Hindcasting* the state of the sea depends on wind information (speed, 

 duration, area of sea covered, and rate of growth and/or decay) obtained 

 from weather maps covering a six-hour period. The wind data is used in 

 conjunction with certain empirical-theoretical formulations to produce 

 an energy spectrum of waves at the place and time of interest. The energy 

 spectrum is a good descriptive tool, because it gives information on the 



*Hindcasting is the prediction of an event after it has occurred but has 

 not been observed. 



