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bulent action of the surf zone or to currents that may exist at times parallel to 

 the beach. After a few months the cables usually will be covered by sand to 

 such depths that they cannot be recovered. 



The sanding down takes place for two reasons: first, the fluidity of the 

 sand (especially in the surf zone) will allow the cable to settle until it is covered 

 to a depth of a few inches or more; and second, the movement of sand bars, the 

 movement of sand onshore and offshore, and the movement of sand along the 

 shore will alternately undercut and bury the cable until it may be covered to a 

 depth of several feet. During the summer when the sand moves toward the 

 beach, the offshore cable may be very near the sand surface, or actually ex- 

 posed. Directly under the summer berm on the beach the cable may be buried 

 as much as 10 feet. Conversely, during the winter the cable may be near the 

 sand surface in the surf zone while offshore it may be buried several feet. The 

 cable seldom, if ever, will be exposed along its entire length. 



The greatest danger to the cable exists during storms when the waves ap- 

 proach the shore at a sharp angle. The waves may cut a scarp several feet 

 deep which will expose the cable to the turbulence and littoral currents of the 

 surf zone during the storm. 



Under favorable conditions the armored cable need be used only to cross 

 the surf zone. Unarmored cable can then be spliced to the armored cable and 

 laid along the bottom to the instrument site. The splice normally does not have 

 the full strength of the cable and care must be taken to prevent tension at this 

 point. Anchoring the cable near the splice will reduce the tension in the splice. 

 An installation of this type was made at Oceanside, California (Wiegel, 1949). 



When reefs exist along the beach or the bottom offshore is covered with 

 rock, the cable cannot sand-down and special anchoring of the cable is necessary 

 to hold the cable in place. Anchoring prevents wear of the cable on sharp edges 

 of rocks and prevents excessive tension in the cable due to long lengths of cable 

 being exposed to underwater currents. The problem of rocky bottoms offshore 

 can be dealt with effectively by having a deep-sea diver walk the cable, laying it 

 around and between the rocks and perhaps anchoring the cable periodically with 

 concrete blocks set on top of the cable. No satisfactory technique has been de- 

 veloped for installing cables over reefs in the surf zone. 



Installation of Electrical Cables by Small Craft - The length of cable usually 

 installed for a wave recorder varies between 1000 and 5000 feet, depending upon 

 how far offshore the desired depth of water can be found. Cable-laying ships 

 cannot be used economically to install these short lengths of cable. It is, there- 

 fore, necessary to use small boats, landing craft or amphibious vehicles to per- 

 form this operation. The DUKW is used more often than the other craft since it 

 can be loaded with the cable, driven to the shore site and used to lay the cable in 

 one operation. The remarks which follow apply directly to the use of a DUKW 

 to install the cable, but should also apply in general to the use of any small craft. 



Cable-spool holders have been designed to mount 2500 -foot spools of 

 armored cable in the cargo compartment of a DUFCW. The design includes a 

 foot brake which acts on the rims of the spool to hold tension in the cable as it is 

 being laid. Without the foot brake the spool will spin, due to the weight of the 

 cable hanging in the water, and cable will be unreeled faster than the craft prog- 

 esses. 



By faking the cable (coiling the cable to form a "figure eight"), the cable 

 can be played out without twisting. A full spool of armored cable (2500 feet) can 



