direct signal and the echoes are quite distinct 

 and may be distinguished from the background 

 noise. The echoes aid in verifying the implo- 

 sion, and further, from the spacing of the 

 echoes, the relative depth of the implosion can 

 be determined. Should the glass ball break 

 before reaching the bottom, paired echoes are 

 received, whereas only single equally spaced 

 echoes are received when the glass ball is 

 broken on the bottom. 



6-60 Recording Ball Breaker Data.— Graph 

 traces of direct signal and echoes obtained with 

 a Brush recorder are forwarded along with the 

 M-sheet. The ship's name, cruise number, 

 core number, station number, date, and time 

 should be noted on the graph. 



6-61 Maintenance of the Ball Breaker. — 

 After each lowering, the ball breaker should 

 be washed to remove any sediment that might 

 hinder its action. When necessary, it should 

 be wire brushed and painted to prevent cor- 

 rosion. 



6-62 SMALL BOTTOM SAMPLERS.— 

 Various bottom samplers are used to obtain 

 small samples of the superficial layers of bottom 

 sediments (fig. 6-13). They are particularly 

 useful where it is desired to gather rapidly large 

 numbers of small samples in a particular area. 

 The samples are stored in canvas sample bags 

 or mason jars and properly labeled. All sample 

 data are recorded on the Al-sheet. 



6-63 Clamshell Snappers.— There are 2 

 general types of clamshell snappers currently 

 used on Navy survey ships. One is about 30 

 inches long and weighs about 60 pounds. It 

 is ruggedly constructed of stainless steel. The 

 cast stainless steel snapper jaws are closed by 

 heavy arms actuated by a strong spring and 

 lead weight. There is a foot device which 

 triggers the jaws. In the open position, the 

 foot extends below the jaws so that it strikes 

 the bottom first. The impact moves the arms 

 up releasing the jaws which snap shut with 

 considerable force. The jaws trap about a 

 pint of bottom material. This snapper is 

 equipped with tailfins and is lowered from the 

 oceanographic winch. 



A smaller type of clamshell snapper, called 

 a mud snapper, is about 11 inches long and 

 weighs 3 pounds. It is attached to the 

 bottom of a sounding lead by means of a hole 

 drilled in the lead. The jaws are cast bronze 

 and are actuated by a spring. The tension 

 on the spring may be adjusted by tightening 

 or loosening a screw cap. The jaws are held 

 open by engaging two trigger pins within the 

 jaws. Care should be observed when handling 

 the snapper in the open position as a slight 



H. O. 807 



350«76 O — 5« 6 



jar may accidently snap the jaws causing injury 

 to the fingers or hands. The mud snapper 

 and sounding lead may be operated in shallow 

 waters by hand lowering or it may be lowered 

 from a bathythermograph or oceanographic 

 winch. 



6-64 Orange Peel Bucket Sampler. — Orange 

 peel bucket samplers are used to obtain 

 bottom samples in shallow waters. Those used 

 on Navy survey ships weigh 45 pounds and 

 hold about 300 cubic inches of sediment when 

 full. They are operated from the oceanographic 

 winch. A small hook attached to the end of 

 the lowering wire supports the sampler as it is 

 lowered and also holds the jaws in the open 

 position. When contact is made with the bot- 

 tom, the sampler jaws sink into the sediment 

 and the wire tension is released, allowing the 

 hook to swing free of the sampler. Upon 

 hoisting, the wire takes a strain on the closing 

 line which closes the jaws and traps a sample. 

 One end of the closing line is attached to the 

 wire and the other end is fixed to the handle 

 which activates a ratchet chain and sheave 

 that close the jaws. The closing line supports 

 the sampler as it is being hoisted. To prevent 

 washing out of the sample from the top, it is 

 recommended that a canvas cover be used. 

 Once on deck, the sample is discharged by 

 slacking off the closing line. The sample is 

 placed in a mason jar and properly labeled. 



Owing to its sturdy construction, the sampler 

 requires very little maintenance. After each 

 lowering, the sampler must be washed to 

 remove all sediment. All moving parts should 

 be lubricated with light machine oil. When 

 necessary, the sampler should be wire brushed 

 and painted to prevent corrosion. 



6-65 Underway Bottom Sampler, The 

 Scoopfish (fig. 6-13). — The underway bottom 

 sampler, or scoopfish, is designed to sample 

 rapidly without stopping the ship. It is lowered 

 from the bathythermograph winch in depths 

 less than 100 fathoms from a ship underway 

 at speeds not over 15 knots. The sampler 

 weighs 1 1 pounds and is 15 inches long. Samples 

 ranging from mud to coral have been obtained. 

 Mud samples weigh up to about 50 grams, but 

 gravel and coral samples may contain only a 

 few fragments. The instrmnent is made of 

 stainless steel and is quite rugged. When 

 lowering, care must be taken that the nose lid 

 is not prematurely released as the sampler 

 enters the water. The scoopfish is allowed to 

 fall freely in the same manner as the bathyther- 

 mograph. During its descent, the towing arm 

 is engaged toward the rear, and the nose lid is 

 hooked back in open position. Upon striking 



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