TM Noo 377 



desirable to monitor every few minutes, preferably at the time of each wave 

 observation,, Unfortunately,, only spot observations were made., since equip- 

 ment was not available to record the wind velocity continuously. 



The wind speed and direction were recorded for B3ELS series k s 7 3 8* 3> 

 10, 11, 12 and 1.3 from an anemometer system owned by the Weather Bureau 

 (model FteO) and permanently mounted on the light station » The instrument 

 (manufactured by the Electric Speed Indicator Co 0j> Cleveland., Ohio) is pro- 

 vided with a pair of visual readout dials mounted in the tower communications 

 room The speed is registered in knots, and the direction in degrees true. 

 The unit is mounted off the northeast comer of the helicopter landing deck 

 as shown in figure IV-4o The anemometer is fastened about 1 meter above a 

 rail on the catwalk that extends out from the top deck of the tower at a 

 height of 22 meters above the water. Unfortunately., the position of mounting 

 is about 25 meters directly north-northeast of the beacon coltunxu The 

 column is about 2c 5 meters in diameter at the base., but widens to about 

 5 meters above to provide for the beacon housing section The tover must 

 certainly affect the anemometer measurement when the wind is from the SSW 

 and southo Fortunately, winds were from the vest ;r southwest during most 

 of the wave observations. 



The BBELS wind measuring sysxem was checked out by a Weather Bureau 

 technician in August, of 19&4 and was found to be working properly « However, 

 during the winter and spring of 196^-1965 it was suspected that system accuracy 

 was becoming degraded, probably due to bearing wear,. This was indicated by 

 a loud squeaking of the cup mounting shaft as it whirled in the wind,, During 

 the series BBELS Ik on 9~1^ June 19^5,, a comparison check was made of the 

 BBELS anemometer system with a newly acquired portable anemometer system (Type 

 C, 1^00, built by the Belfort Instrument Co . Baltimore, Maryland}* The out- 

 put of this portable system provides a continuous analog voltage of wind speed; 

 but, in contrast to the BBELS system, the wind direction is indicated by an 

 array of eight wind direction lights whereby, at best,, one can estimate the 

 wind direction to within 22c 5° The portable unit, having an indicated error 

 (for wind speed} stated by the manufacturer to be within + 0.4- m sec" 1 ^ was 

 sensitive and accurate enough tc evaluate any gross speed error in the BBELS 

 system,, 



This study, using the portable anemometer system, was made for two reasons; 

 (l) to detect any gross biasing of the BBELS anemometer speed sensor observable 

 within the limits of the accuracy of the nortable unit; and (2) to determine 

 any difference in the observed wind speed when measured from the upwind side 

 of the tower deck as compared to measurements from the northeast, side of the 

 tower decko 



During period?, of westerly winds, it was found that wher the portable sys- 

 tem was mounted at the same ^evei as the BBELS system (2 meters above the upper 

 deck), first at the windward and then a'o the leeward side,, there was negligible 

 difference in the indicated mean wind speed,, Hence , for practical purposes, 

 it was assumed that, for westerly winds at least, the BBELS anemometer was 

 capable of measuring accurately the approximate wind, speed and direction at 



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