f. Submarine wave recorder 



One of the most recent developments in the field of oceano- 

 graphic instrumentation is the use of a submarine as a hovering, 

 submerged, stable platform from which to measure oceanographic 

 variables. The Hydrographic Office has recently conducted tests with 

 the Westinghouse sonic surface scanner which is essentially an 

 inverted echo sounder mounted on the deck of a hovering submerged 

 submarine.. The travel time required for the vertical sound beam to 

 go from the submarine to the sea surface and return (in a 3°-cone) 

 is proportional to the height of the water above the submarine. Thus, 

 changes in water height above the submarine are recorded as changing 

 wave height. 



The manufacturer claims the surface sonic scanner can detect 

 changes in surface wave height to the nearest foot when the submarine 

 is submerged at a depth of about 100 feet. This assumes that the 

 amplitude of the submarine roll is small at a depth of 100 feet, which 

 is usually the case, except when extremely rough conditions occur at 

 the surface. The Hydrographic Office currently is analyzing and 

 evaluating data taken with the sonic scanner by computing power 

 spectra with a high speed digital computer 



3. Fixed wave gauges 



a. Beach Erosion Board step-resistance gauge (abstract) 



This gauge (the prototype of the resistance wire wave staff) 

 utilizes a 25-foot length of sealed pipe which houses a series of 

 electrical contact points spaced at intervals of 0.2 foot. The contact 

 points (made from spark plugs) are connected to a resistance circuit 

 within the pipe. The gauge is mounted vertically on a supporting 

 structure, such as a pier, and the bottom of gauge is set below the 

 lowest expected wave trough; the top of the gauge must be above the 

 highest expected wave crest. The exposed tips of the plugs are covered 

 with lead to reduce corrosion effects. In order to overcome the short- 

 circuiting effects of the sea water film which adheres after a wave 

 passes, the gauge pipe and the bases of the spark plugs are covered 

 with neoprene. 



A constant voltage, 115- volt, a.c. transformer supplies power to 

 the gauge; its primary is connected through a timing switch to provide 

 automatic programming. Alternating current is supplied to prevent 

 polarization and is converted (through a selenium bridge rectifier) 

 to a proportional d.c. current, which in turn drives the recording unit 



VII- 1 2 



