102 



HYDROGRAPHIC MANUAL 



Figure 40. — Scoopfish bottom sampler. 



and the procedure can be repeated. After 

 lowerings have been completed, the instru- 

 ment should be washed with fresh water and 

 all moving parts given a coat of light ma- 

 chine oil. 



3-130 Phleger corer. — The Phleger corer 

 (Fig. 41) is used to obtain cores about 12 

 inches in length, and may be used to obtain 

 cores 36 inches long. The corer consists of 

 a cylindrical core barrel with a cutting bit 

 and core catcher, an upper tube with spring, 

 check valve, and tail fin assembly, and about 

 40 pounds of lead around the barrel to pro- 

 vide driving thrust. Plastic liners, 1 >/i inches 

 outside diameter, are used to hold the cores. 



The Phleger corer is used with the oceano- 

 graphic winch. It may be used with the BT 

 winch in depths less than 50 fathoms. In 

 medium soft bottom and depths less than 30 

 fathoms, full length cores can be obtained 

 without using the detaching device. In great- 

 er depths, this mechanism should be used. 

 When the detaching device is used, it is at- 

 tached to the hoisting cable and carries the 

 weight of the corer during descent. A trip- 

 ping line about 18 feet long is attached to 

 the arm, and a 14-pound sounding lead is 

 attached at the other end of the line. The 

 corer is secured to the detaching mechanism 

 by a 20-foot section of y, g-inch chain. 



The instrument is prepared for use by in- 

 serting a section of plastic tube of proper 

 length in the coring tube, then the core 

 catcher and cutting bit are inserted and se- 

 cured. The corer is then attached to the 

 release mechanism and lowered away. The 



Figure 41. — Phleger corer in position for lowering. 



cores should be preserved intact in the plas- 

 tic tubes, each end of the tube being corked 

 or covered by a plastic cap, or by extruding 

 the sample into ball-mason jars. Each sam- 

 ple must be properly logged and identified. 

 Various other devices have been used to 

 obtain bottom cores at all depths. The Kul- 

 lenburg piston corer is capable of taking 

 cores 12 feet long, and the Ewing piston 

 corer can take a core from 20 to 75 feet in 

 length. The Kullenburg corer can be used 

 with •"'■j^-inch wire in limited depths and 

 without using the free fall feature. The 

 Ewing corer requires much heavier equip- 

 ment. 



3-131 Dredges. — Dredging is generally 

 confined to the continental shelf because of 

 the weight of gear required. A sturdy winch 

 and cable of at least -Vjj-inch diameter is 

 required. Dredging must be done at slow 

 speed, and can be done by drifting with the 

 wind or current. The dredge samples the 

 surface layer and will trap large stones 



