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marker buoy system that is proving to be more satisfactory comprises a short 

 line and a spar-type buoy. The basic idea behind this scheme is to provide a 

 buoy that holds the short line taut at all times to prevent continual working of the 

 line and to prevent failure by snapping action. One such scheme, used by the 

 Beach Erosion Board, employs a wooden spar buoy, approximately 5 feet in 

 length, which is connected to a 3/8" wire cable. The length of the cable is ad- 

 justed according to the water depth so that the buoy is exposed only at low tide. 

 A positive net buoyancy is assumed at all times, except possibly during the 

 trough of large waves at low tide. 



A second example of the short-line spar buoy scheme is provided by an 

 installation made at Point Pino, California, by the University of California. 

 This system employs a 30-foot metal spar buoy 6 inches in diameter, and a 5- 

 foot length of chain. The chain is connected between the top of a 6-foot, 1500 

 pound tripod and the buoy. The length of the chain is adjusted so that the top of 

 the buoy is exposed at low tide. A net positive buoyancy exists at all times and 

 is equal to 150 pounds at the connection between the chain and the tripod when the 

 buoy is completely submerged. This installation was checked after five months 

 service and was found to be in good condition; very little wear of the chain had 

 taken place. 



The disadvantage of the short-line spar buoy system is twofold: (1) spe- 

 cial provisons must be made to lower and lift the instrument and (2) the replace- 

 ment or cleaning of buoy requires lifting the instrument. The first difficulty is 

 easily overcome. The instrument can be lowered by a separate line attached to 

 the tripod byahook which will free itself when the instrument reaches bottom. 

 The instrument can be lifted by lowering a chain noose around the buoy to con- 

 tact the buoy chain near the top of the tripod. When the noose is pulled tight by 

 the lifting line, the two chains inter-link so that the tripod can be raised. 



The second disadvantage of the short-line spar buoy system, the incon- 

 venience of lifting the instrument for periodic cleaning of the buoy, cannot be 

 overcome simply. Periodic cleaning must be made to prevent excessive sea 

 growth on the buoy. If the growth is allowed to accumulate, the downward drag 

 force exerted by the motion of the water may be sufficient to overcome the net 

 buoyancy with the result that snapping action could take place. 



A third scheme combining the features of the short-line spar buoy type 

 marker and the Coast Guard buoy type nmarker has been developed. This sys- 

 tem utilizes (1) a median size spar buoy (15 feet long, 7 inches in diameter, 149 

 pounds total weight), (2) a small chain (3/8") connecting the buoy to a section of 

 large chain (1") which acts as a "variable anchor", (3) a lifting chain (3/8") be- 

 tween the 1" chain and the tripod, and (4) a 1200-pound tripod. The buoy size is 

 determined by the amount of chain to be supported, which includes a section of 

 the large chain. The system is designed so that at a -1-foot tide, the buoy is 

 exposed 2 feet; at a +4-foot tide, the buoy is totally submerged. The large 

 chain, therefore, acts as a "variable anchor" in that it reduces the motion of 

 the spar buoy, maintains tension in the buoy chain, and prevents snapping action 

 in the chain. 



Installation of Electrical Cables - The installation of the electrical cable bet- 

 ween the offshore tripod and the shore station is a relatively simple task under 

 favorable conditions and with proper equipment. Favorable conditions include 

 a straight, sandy beach without reefs, and a sand bottom from the beach to the 

 instrument. Under these conditions an armored cable can be laid along the bot- 

 tom without anchors or additional protection and little or no cable wear will take 

 place. The cable will quickly "sand down" so that it is not exposed to the tur- 



