707 
THE MEASUREMENT OF UNDERWATER EXPLOSIONS FROM SERVICE WEAPONS 
AT THE UNDERWATER EXPLOSIVES RESEARCH LABORATORY (UERL) 
by 
J. S. Coles, March 196 
Abstract 
The instruments and methods used for measuring the effective- 
ness of and obtaining other data vertinent to underwater explo 
Sions of full-scale service weapons is described in detail, The 
theory and use of mechanical gauges, including the UERI+diaphragn, 
NOL ball—crusher, BuShips Modugno, and momentum gauges, are dis- 
eussed; the practical application of piezoelectric gauges to 
full-scale measurements is illustrated. The highly specialized 
techniques involved in handling such a combination of heavy with 
friable equipment at sea is described. 
I, INTRODUCTION 
The comparison of various explosives in full-scale service weapons was 
begun by the Underwater Explosives Research laboratory (UERL) in December 
1942 at the request of the Bureau of Ordnance of the United States Navy. 
The very early work was done under great pressure and made use of the exist- 
ing facilities at the UERL, which required the rather cumbersome coordina 
tion of several vessels, This work has been described previously [1 a 
When it became apparent after the first series of tests that there would be 
a large amount of such full-scale testing to be done, a special vessel was 
purchased for this purpose and converted into a floating laboratory, This 
vessel, Schooner RELIANCE, has been in continuous use since that time and 
is fully equipped for the recording of the signals from eight piezoelectric 
gauges, as well as servicing the mechanical=type gauges in use at UERL, 
The measurement of the underwater effectiveness of an explosive ulti- 
mately involves the determination of damage to an actual target. In prac— 
tice, this is best accomplished by measuring certain parameters of the shock 
wave resulting from an underwater explosion, and by measuring the actual 
damage to small targets such as small steel diaphragms. 
The variation of pressure with respect to time (Fig.1) may be measured 
at a given point in the water by means of a piezoelectric gauge; from this 
pressure-time curve, the peal pressure P,, momentum or impulse I, and the 
energy E of the shock wave may be obtained. For most cases, the pressure— 
time curve may be represented by 
*The list of references has been deleted. 
