Page 649 EADio acoustic ranging 6845 



material used on the heads of safety matches; it is placed in contact with the end of the 

 fuse. The fuse is lighted by simply striking the end of the tube with the edge of a safety 

 match box. 



A bomb should be thrown overboard when the flame has progi'essed about 2 inches 

 into the fuse. It will then rarely be extinguished by the water. To eliminate any 

 possibility of holding the bomb too long after the fuse has been lighted, some bombers 

 press the fuse lightly between the thumb and forefinger to follow the progress of the 

 flame by its heat as it burns internally. 



6845. Throwing Bombs Overboard 



After the bomb fuse has been ignited, the bomb is held for a few seconds until 

 nothing but smoke is issuing from the end of the fuse. This indicates that the fuse 

 is burning internally and will not be extinguished when submerged. The bomb must 

 be thrown overboard within 5 seconds after ignition of the fuse regardless of external 

 or internal evidence. The bomb should be thrown overboard in such a manner that 

 it is upright when it strikes the surface of the water, in order not to dislodge the deto- 

 nator-^this is especially important in the case of cast-iron containers. This is done by 

 holding the bomb with the fuse up and giving it a slight rotary motion as it leaves the 

 hand. 



Bombs must be thrown outboard 10 or 1 5 feet beyond the ship's side so that there 

 will be no danger of their being carried into the propeller by suction. 



To ensure a secure footing when handling bombs on a wet deck, suitable matting 

 or safety treads should be used on the deck at the bombing station. 



6846. Depth of Detonation 



The rates at which bombs of various kinds and sizes wUl sink may be determined 

 by experiment. For a tin can bomb, use a lid with no hole in it, and for a cast-iron bomb, 

 plug the fuse hole with beeswax. Do not use a bomb with a detonator in it. Lash 

 light twine, such as sail twine, to bombs of various sizes and determine the rate of sink- 

 ing by measuring the amount of twine payed out in a given niunber of seconds, timed 

 with a stop watch. The twine must be coiled on deck so that it will pay out freely 

 and not retard the rate of sinking. 



When surveying in shoal water, or at other times, it may be desirable to reduce the 

 depth of detonation. A bomb may be prevented from sinking beyond a predetermined 

 depth by suspending it from an inflated paper bag used as a buoy, by a length of twine 

 equal to the desired depth of detonation. Any paper bag of sufficient size to support 

 the weight of the bomb in water may be used. Pieces of wood or other similar articles 

 must not be used for floats, because of the hazard left in case the bomb fails to explode. 

 The paper bags are safe for they will soon become watersoaked and let the unexploded 

 bomb sink to the bottom. The string should be light so that it will break if it fouls 

 anything. 



6847. Bombing at Buoy Stations 



A buoy is often located with reference to other buoys by R.A.R. distances. Where 

 this method of location is used, bombs must be exploded at one of the buoy stations. 

 The same types of bombs are used, but they must be thrown overboard at the buoy 

 when it is near enough to the bombing station, and more precise timing is requu^ed on 

 the part of the bomber. As explained in 2533, there are two general methods for 

 locating a station in this manner. 



