d) Squared peak wave height . 



e) Linear integrated wave height. 



f) Squared integrated wave height. 



These values are presented on the vertical axis of the spectral 

 plot with the corresponding wave period presented on the horizontal 

 axis of the plot. 



The magnetic tape recorder usually records wave conditions continu- 

 ously using a tape speed of 1/2 inch per minute. One roll of 1/4 inch 

 wide magnetic tape 1,250 feet long, records continuously for approximately 

 3 weeks. 



The magnetic tape recorder has a built-in calibration generator (sine 

 wave) with a period of 4 seconds. The calibration signal is adjusted to 

 provide an amplitude equal to that produced by the wave gage for full- 

 scale recording on the strip chart and magnetic tape. This calibration 

 signal is recorded for 30 minutes every 12 hours to provide a standard- 

 ization signal to compensate for changes found in magnetic tape from roll 

 to roll, and to calibrate the entire spectrum analyzer in the laboratory. 

 The calibration signal is timed by a program clock connected with the 

 tape recorder. 



3. Types of Wave Gages 



The staff type step-resistance wave gage is available for three 

 different applications: 



a) Series step-resistance type for use in fresh water. 



b) Parallel step-resistance type for use in salt water loca- 

 tions where little or no change occurs in salinity. 



c) Relay-operated step-resistance type that will operate in 



either fresh water or salt water and where wide changes 

 in salinity occur. 



The accuracy of the recording taken with the fresh-water, series, 



step-resistance gage and the salt-water, parallel, step-resistance gage 



is about plus or minus 5 percent, plus the spacing of one staff-sensing 

 point. 



The accuracy of the recording taken with the relay-operated step- 

 resistance gage is about plus or minus 2 percent plus the spacing of one 

 staff sensing point. Due to the increased accuracy expected of this gage, 

 servicing and cleaning of the sensing elements may have to be performed 

 more often than on the other two step-resistance gages. This service 

 will depend on local conditions of sea growth at the gage site. 



The sensing units for the staff type step-resistance wave gages are 

 molded from epoxy resin in 5-foot lengths, and are stacked in a steel or 



