ginning, the Ice Patrol has attempted many means by which it was hoped 

 to shorten the life of a berg. These have included gunfire, demolition 

 charges, land mines, depth charges, fire hoses and an intrepid Ice Patrol 

 cutter even has been observed to ram an iceberg. In all cases, except 

 perhaps the last, there were little relative effects to be noted. 1 



In a more modern approach to the problem, including thoughts of air- 

 craft operations, a group of officers from the International Ice Patrol and 

 U.S. Coast Guard Headquarters visited the Snow, Ice and Permafrost 

 Research Establishment at its main offices in Wilmette, 111., during 

 November 1958. That organization, a branch of the U.S. Army Corps of 

 Engineers, has had much experience with the properties of glacial ice and 

 its demolition. Results of discussions at those offices revealed many 

 interesting and progressive treatments in the use of explosives in ice. 

 These included employment of "shaped" charges and special bomb and 

 rocket designs. A disappointing note, however, in the use of conventional 

 explosives is illustrated by the following principle: 



The optimum depth that an explosive charge is detonated for com- 

 plete utilization of the explosion in demolishing the substance within 

 the crater produced theoretically is given by the equation : 



dc — ( 1 \/ut 

 where: 



dc = depth of the crater produced in ft. 

 iv = weight of the explosive in pounds 

 c = a constant which is approximately 4 for glacial ice 



Thus a 1,000 lb. charge must be detonated at a depth of 40 ft. for 

 the maximum effect, producing a crater also 40 ft. deep and about 

 80 ft. in diameter. 



This formulation reveals that the maximum theoretical effect that a 

 1,000 charge of modern conventional explosive would have is the breakup 

 of about 70,000 cu. ft. of ice. This is 1,900 tons and means that a hundred 

 such charges would be required for the destruction of an average-sized 

 berg. Such a practice is physically, as well as economically, unsound. 



Melting by heat is equally impractical. By simple physics it can be 

 seen that since the heat of fusion of ice is about 144 Btu/lb, it would re- 

 quire 28 billion (10 9 ) Btu's of heat energy to melt a medium berg of 

 100,000 tons. This represents the complete conversion of the heat energy 

 contained in 2.4 million gallons of gasoline. 



Ice Patrol officers have long been aware of the experiments of the late 

 Prof. II. T. Barnes of McGill University who, in 1926, conducted experi- 

 ments on grounded icebergs off Newfoundland using thermite explosive 

 charges. The report of Professor Barnes' work 2 showed profound results. 



1 Previous iceberg demolition tests conducted by the Ice Patrol are described in Coast Guard Bulletins 

 of this series for the Ice Patrol Seasons of 1916, 192:1, 1924, 1926 and Bulletin No. 19 — Part ::. 



- Marine Observer, Vol. V, No. 59, Nov. 1928, Proceedings of the Royal Society, London, Vol. 1 14A. 



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