3-5 AMP DPST 

 FUSE SWITCH 



ISOLATION 



TRANSFORMER 



1 TO 1 



90-135 V. PRIMARY 

 117 V. SECONDARY 

 CONSTANT VOLTAGE 

 TRANSFORMER 



I RELAY ~ ~ 



T • I "^ Ir^fd FILTER |7^fd 



|4^fd 



VARIABLE VOLTAGE 

 TRANSFORMER 



RELAY CONTACTS NORMALLY CLOSED TO 

 RECORDER TERMINALS. OPEN FOR '/. 

 SECOND PER ONE MINUTE 



Figure 10-3. Schematic diagram of electrical circuit of electric wave staff. 



36 CONTACT POINTS 



STEP RESISTANCE GAGE SECTION 



jure 10~4- 



Electrical circuit of step-resistance gage 

 of electric wave staff. 



6. All the required information is properly 

 recorded on the chart paper for each observa- 

 tion. 



10-26 ANALYSIS OF WAVE TRACES.— 



The analysis of wave traces made by the electric 

 wave staff are usually carried out ashore. 

 However, there are times when special studies 

 require that analyses be carried out aboard ship 



108 



during the course of a survey. This may be 

 done in the following manner: 



1. From the chart record of the observation 

 pick out the dominant wave train. 



2. Find the average period (T) in seconds. 

 This can be done quickly by dividing the total 

 time in seconds (excluding hauling in, etc.) by 

 the total number of dominant waves, if the 

 dominant waves, which are the ones to be 

 measured, are continuous throughout the record. 

 If they are not continuous, the individual 

 periods will have to be averaged. 



3. Divide the total time in seconds, of actual 

 wave recording (excluding any time on record 

 which represents hauling in, etc.) by T (average 

 period) to obtain the total number of possible 

 waves of this period. 



4. Divide this total by 3. 



. ., ,. , /total number\ 



5. Measure this number I ^ I 



of highest waves starting with the highest wave 

 and working down, using the calibration scale 

 drawn up on the side of the calibration card. 

 This card is calibrated and provided for each 

 wave staff. 



6. Take the average height of these n 

 highest waves. This gives tTie apparent sig- 

 nificant height. 



7. Using the dynamic calibration curve for 

 the 50-foot systern, shown in figure 10-5, pick 

 off the true significant height using the appa- 

 rent significant height and average period. It 

 should be noted in interpolating values from 

 the curves in figure 10-5, that because the con- 



H. O. 607 



