The gage will operate in salt-water locations that have little or no 



change in salinity. If the gage is placed in locations having significant 



salinity changes, the wave record will vary in accuracy with the changes 

 in salinity. 



2. Fabrication of a Parallel Step-Resistance Gage 



Fabricate the required number of S-foot epoxy gage sections as 

 outlined in Figure 18. The top gage section will have the lower value 

 resistor connected to the top five sensing plugs, and the resistors will 

 progressively go higher in value until the highest value of resistors are 

 connected to the five sensing plugs, and the resistors will progressively 

 go higher in value until the highest value of resistors are connected to 

 the five sensing plugs on the bottom gage section. The cable from each 

 wave gage section (molded as part of the section) should not extend more 

 than 10 feet from the top of the gage mount. The resistance in the gage 

 cables and leads from the transformer unit connected to the gage cables 

 and leads from the transformer unit connected to the gage cables are part 

 of a low- voltage, current-sensitive circuit. The resistance of these 

 connections must therefore be low; long leads or high resistance con- 

 nections in this circuit must be avoided in order to provide best gage 

 linearity. Wire size in the cables molded into the gage sections should 

 not be smaller than 2-conductor No. 20 AWG in parallel. 



Fabricate the transformer unit as shown on Figure 19. Wire the 

 transformer unit as shown on Figure 20. Be sure that all connections in 

 this unit are well made and well soldered. This unit may be filled with 

 a clear potting compound available from Dow Corning Company, their No. 182. 

 If this unit is not filled, care should be taken to ensure that it is 

 watertight . 



Fabricate the voltage control, rectifier-filter unit, and programmer 

 as shown on Figures 10 and 21 and wire as shown on Figures 10 and 22. 



Strip-chart recorder chart speed may be modified, if desired, as 

 outlined in Section VIII. Fabricate the signal connecting cable for 

 the strip-chart recorder to the desired length using 2-conductor No. 18 

 AWG cable as shown on Figure 11. 



Fabricate the metal gage holder to the required length shown in 

 Figure 12. Suitable mounting brackets for the gage holder should meet 

 local installation requirements. Mounting brackets must be strong enough 

 to withstand the forces of wave action expected at the gage site. A 

 bracket design that has been used on vertical piling is shown on Figure 

 13 which may serve as a guide. 



Paint the gage holder with two coats of primer and two coats of any 

 good commercial anti-fouling paint. Government agencies may use Government 

 Services Administration GSA Stock No. GS8010-550-8305 and GS8010-290-6651, 

 respectively. DO NOT PAINT THE GROUND ROD. Paint the gage sections that 

 are below and at the water line with three coats of anti-fouling paint. 

 Clean the sections of mold release prior to painting. DO NOT PAINT THE 

 LEAD SENSING TIPS. 



Text resumes on page 40 

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