in Reference 11. However, the basic hydrodynamic stabilization of the fixed 

 vertical accelerometer can be understood from Figure 3. The rigid tripod tail of 

 the buoy (length L-^) has a weight G attached to it by a wire rope of length L^. A 

 wave induced moment M would result in a buoy tilt of 6 degrees. In this condition, 

 an erecting moment of F-, times L-i would be obtained, where F-^ is the perpendicular 

 component of the wire tension to the tail. During this trial, a wire length of ^+0 

 meters was used such that Lg can be assumed to be much greater than L^ and thus the 

 angle a approaches zero. Therefore, the erecting moment can be expressed as 



F 1 • L x = G • sing • L^ (l) 



This rather simple method for vertical stabilization of the accelerometer seemed to 

 function very well with no tilting of the sensor observable. 



DTNSRDC deployed an ENDECO Corporation Wave-Track Directional Buoy during the 

 trial. This buoy is the result of development work at the University of Rhode 

 Island as well as ENDECO Corporation and has been the subject of several 

 papers. The Wave-Track buoy was also deployed during the ARSLOE experiment as 

 reported in Reference 15. The configuration of the buoy is shown in Figure k. The 

 sphere of the buoy (fiberglass) houses the electronics, transmitter, and batteries 

 for the buoy, while the lower pendulum assembly (PVC and stainless steel hardware) 

 houses the pitch-roll sensors, flux gate compass, and accelerometer. The pendulum 

 assembly acts as a moment arm to tilt the buoy in response to the orbital motion of 

 the incident wave field. This buoy has thus been classified as an orbital 

 following buoy. Because of its inherently stable design the Wave-Track buoy is not 

 subject to the capsizing problems associated with the discus slope following buoys. 



The signals from the buoys were recorded in analog form each using a Honeywell 

 Model 5600 recorder. These recorders provided backup to the computer systems and 

 digital recording of the data. Delft University and Datawell Corporation employed 

 Hewlett-Packard microcomputer systems, while DTNSRDC used a Digital Equipment 

 Corporation microcomputer system for the purpose of digital data collection and 

 analysis. 



TRIAL DESCRIPTION 

 TYDEMAN is a 90 meter open ocean research ship equipped with various cranes 

 and winches necessary for general oceanographic research. The design of the ship 



