The model tank tests were quite successful but they were made in 

 long-crested waves of relatively high frequency. It was necessary to 

 test under actual sea conditions, in order to establish any real 

 confidence in the system. 



Preliminary tests in Chesapeake Bay indicated that the SPLASHNIK 

 had a life in excess of 8 hours and a range of about 11 miles over flat 

 water. Since transmission of the signal is on a line-of-sight basis, 

 one expects trouble in high seas as separation of SPLASHNIK and ship 

 increases . 



In a recent full-scale trial, the SPLASHNIK system was tested in 

 conjunction with a shipborne wave recorder in moderate states of sea 

 (4-5) . Several buoys were used in this experiment with varying degrees 

 of success. One SPLASHNIK turned over, which was quite unexpected. A 

 few SPLASHNIKS ceased transmitting after 5 or 10 minutes because their 

 batteries were shaken loose. (Batteries are now firmly secured.) 

 Several, however, transmitted successfully for periods ranging from 

 half an hour to in excess of 3 hours. It is believed that lengthening 

 the transmitting antenna by 1 foot and the SPLASHNIK float by 1 foot 

 on each side will increase chances of successful transmission and 

 reception of the signal. 



Several simultaneous wave recordings were made with SPLASHNIKS and 

 the shipborne wave recorder. Two of these events, each 20 minutes long, 

 have been selected for analysis. Case I is depicted in Figure 8. The 

 acceleration spectrum is computed on the Taylor Model Basin analog spectrum 

 analyzer. As expected, energy appears at the low frequencies where it 

 is known not to exist. The arbitrary cutoff is made at oi = 0.342 and then 

 the wave spectrum is computed by Equation [4] (Figure 8b) . In order to 

 compare the SPLASHNIK with the shipborne wave recorder, it must be recalled 

 that the ship was advancing into the waves at about 3.5 knots (to maintain 

 heading) while the SPLASHNIK drifted in the opposite direction at about 



12 



