5237 



HYDROGRAPHIC MANUAL 



Page 470 



nipple and a 90° brass elbow are screwed into each of the tees, which are connected 

 horizontiilly by a short length of l)^-inch brass pipe screwv^d into the elbows. 



The horizontal members that arc; secured to the deck support most of the weight of 

 the assembly. These members are made of 2- by 3-inch angle iron; they are fastened 

 to two K- by 3- by 26-inch iron plates which are secured to the deck by lag screws. The 

 outer ends of the angle irons project slightly beyond the side of the launch and secured 

 to them is a %- by 6- by 22-inch iron plate. The vertical pipes supporting the fish pass 

 through two 1%-inch holes, 15 inches between centers, in this plate. Each pipe passes 

 through two loose brass collars, one above and one below the iron plate. The support 

 of the fish is secured in place by means of set screws through the brass collars. This 

 arrangement provides for a vertical adjustment of the position of the fish. 



Just above the waterline is another hori- 

 zontal support to secure the vertical structure 

 to the side of the launch and prevent lateral 

 movement of the fish. This support consists 

 of two l}4-inch brass side-outlet tees, three 

 short lengths of l^-inch brass pipe, and two 

 brass deck flanges with closed nipples. The 

 tees are drilled so they will slide freely over 

 the vertical pipes. Two setscrews in each tee 

 are used to clamp the pipes in place. The 

 deck flanges are secured to the side of the 

 launch so that their nipples are horizontal. 

 The outer ends of the horizontal pipes screw 

 into the tees, and the inner ends slide over 

 the nipples of the flanges to which they are secured by pins through holes drilled 

 through the pipes and nipples, 



Guys leading forward and aft are secured to the vertical pipes by means of clamps 

 located just above the fish. The guys are }^-inch stranded wire. A safety line attached 

 to a %-inch bronze eyebolt in the top of the fish is fastened to a cleat on deck. The 

 electric cables from the transmitting and receiving units pass through the vertical pipes 

 and pass out of the upper tee openings. 



To install the fish, the assembly is lowered over the side and the angle irons are 

 bolted to the deck plates. The lower horizontal pipes are then slipped over the deck 

 flange nipples and pinned. If th*e draft of the fish is not suitable it may be adjusted by 

 loosening the setscrews in the upper clamps and the lower side-outlet tees, and raising 

 or lowering the fish. The fore-and-aft guys are then fastened on deck and made taut 

 by means of tm-nbuckles. The safety line is fastened and finally the electric cables are 

 connected to the recorder cabinet. 



Where the 808 Fathometer is installed permanently in a vessel, the magneto- 

 strictive elements are removed from the fish and installed in tanks located against 

 the inside skin of the vessel. 



5237. Operation 



In actual field operations, depths from a half -foot below the fish to 160 fathoms have 

 been recorded. For launch hydrography it is used principally in depths less than 100 

 fathoms. Wliere somiding in shoal or moderate depths over comparatively even 

 bottom, a record in greater detail may be obtained by using the fast speed and the scale 



Figure 103.— Support for fish of 808 Fathometer. 



