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“All ice is brittle, especially that in bergs, and it is won-derful how little it takes to accomplish their destruction.A blow of an ax will at times split them, and the report ofa gun, by concussion, will accomplish the same end. ” 1

-–ENSIGN H. RODMAN

Seek and Destroy?The history of iceberg

demolition experiments.

by DR. DONALD L. MURPHYOceanographer, U.S. Coast Guard International Ice Patrol

by DUYANE ALEXANDERMarine Science Technician First Class (ret.), U.S. Coast Guard International Ice Patrol

The shocking sinking of the Titanic made the men-ace icebergs pose to shipping horribly evident.Icebergs are a clear and present danger to marinerstraversing the North Atlantic Ocean. They are theenemy. Why not just destroy them? In the early 20thcentury it was unlikely that very many people

shared EnsignRodman’s optimismon how easy thiswould be, especiallyin the light ofTitanic’s fateful col-lision, but destroy-ing threateningicebergs seemed tobe a reasonablething to try. Fornearly half a cen-tury the CoastGuard InternationalIce Patrol did justthat. The followingsections describe theattempts, sometimesspur-of-the-momentand sometimes withextensive planning.

GunfireIn April 1913, U.S.Revenue CuttersSeneca and Miami

Figure 1: Seneca's crew conducts target practice with the type of gun used in iceberg demolitionattempts in the early 1900s.

IIP History

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many years, circumnavigat-ing the North Atlantic Oceanseveral times and creating agreat hazard to navigation.4

Their destruction was usu-ally accomplished usingstandard Navy-type wreck-ing mines, which had gun-cotton as the explosive agentand were detonated using anelectrical charge from a bat-tery. The Ice Patrol vesselsconducted this importantCoast Guard mission andcarried the wrecking mines,so it was natural to see ifthey would fare any betterthan the gunshots againstthe icebergs.

In May 1923 USCG CutterTampa tracked a particularlyfast-moving iceberg in thewarm (>15° C) Gulf Stream

waters south of the Tail of theGrand Banks. Since this iceberg was well into thebusy steamer lanes and considered particularlymenacing, they decided to use wrecking mines tohasten its demise. The effort was done mostly in thename of experimentation, but the iceberg’s locationimparted an operational urgency to the destructionof this iceberg.5

From May 20–24, Tampa exploded four chargesalongside the underwater portion of the iceberg atdepths ranging from six to 30 feet. Several of theattempts involved attaching the mines to the ice-berg using lines with grapnels. This allowed themines to explode right alongside the iceberg at var-ious depths. Overall, the experiment was consid-ered a success, with the belief that the life of theiceberg was shortened by one to two days, animportant achievement, considering the dangerouslocation of the iceberg. It was clear that the effectiveuse of wrecking mines, while successful in this case,could only be undertaken in calm conditions thatpermitted small boat operations and in warm water,so natural deterioration processes and the explo-sives could work in concert to destroy the iceberg.

The final effort at destroying icebergs using wreck-ing mines was undertaken by Tampa on May 28,1926. It came upon a small to medium iceberg in thesteamer lanes, again in the warm Gulf Streamwaters. Although natural deterioration processes

began taking turns conducting iceberg-scoutingpatrols in the vicinity of the Grand Banks. On April26, less than three weeks after beginning these reg-ular patrols, Miami fired a shot from its 6-poundergun against the vertical wall of an iceberg. Theresult was far less dramatic than Ensign Rodmanwould have predicted since the shot “… had noother effect than to shake down a barrelful of snow-like dust.” While this was hardly a concerted oreven mildly promising effort at iceberg demolition,it marks the beginning of the International IcePatrol’s experimentation with iceberg destruction.2

In the years that followed, Miami and Seneca firedtheir 6-pounder guns at icebergs sporadically,partly for diversion and partly for experimentation(Figure 1). Miami’s efforts on May 26, 1914, involvedfiring 12 6-pounder shots at an iceberg southeast ofthe Tail of the Grand Banks. The results were “…justas effective as if we had stormed the Rock ofGibraltar.” It had become evident that the smallguns on the early patrol vessels were no match forthe icebergs they were charged with tracking.3

MinesOne of the little-known responsibilities of theRevenue Cutter Service in the early part of the 1900swas the destruction of derelict vessels drifting in theocean. Abandoned wooden vessels could drift for

Figure 2: Photo taken minutes after a strike by a 1,000-pound bomb during the1960 tests.

Proceedings Spring 200552

were taking their toll on this dangerous iceberg,Tampa used its 6-pounder gun and 238-poundwrecking mines to speed the decay. The conclusion:“Considerable ice was shaken down, but it is ques-tionable whether the expenditure would be justifi-able in continuing the practice on a greater scale.”That evening, Tampa remained close to the iceberg,warning all approaching ships of its location.6

HeatProfessor H.T. Barnes, a professor of physics atMcGill University andone of the earliest pro-ponents of using ther-mite, a mixture ofaluminum and ironoxide, to destroy ice,was a self-described“ice fighter” whoregarded ice as anenemy to mankind.7

During Modoc’s patrolin June of 1924, he hadseen Ice Patrol’s use ofwrecking mines andrealized that it would bebetter to create anintense thermal shockby igniting thermiteinside an iceberg. Whenignited, thermite createsa violent reaction thatburns at very high tem-peratures, as hot as3,500° C, which is hotenough to melt steel.

In the summer of 1926 inNotre Dame Bay, Newfoundland, Barnes conductedseveral iceberg-destruction experiments using ther-mite and Bermite, a high explosive. In one of thetests, 500 pounds of thermite were placed aboutfour feet into the iceberg and:

“…fired at sundown in order to allow the people ofTwillingate an opportunity to see the spectacle ofthe burning and disrupting ice. The whole thingwas a most wonderful sight when the mightycharge fired and roared, lighting up the iceberg andsurrounding hills like Vesuvius in eruption. Flamesand molten thermite and ice were shot upwards 100feet or more by the explosion which followed. Muchof this berg was disrupted but the full effect of thebig charge was lost to into the air.”8

He concluded that the charge would be much moreeffective if it could be placed 50 to 100 feet into theiceberg using a rock drill, a process, he declared,that could be accomplished from a boat withoutboarding the iceberg.

After the results of Barnes’ 1926 experimentsbecame widely known, the following optimisticassessment appeared in the March 1927 issue ofNautical Magazine:

“…it would appearthat as soon as an iceberg is reportedapproaching the trans-Atlantic steamer routesall that is necessary isfor a handful of men toapproach the berg andwith the judicious useof thermite completelydestroy it in a fewhours.”9

Bombs, Thermite, andCarbon BlackWhile Ice Patrol recog-nized the promise ofBarnes ’ thermiteexper iments , theprospect of takingexplosive charges andboarding or evenapproaching an ice-berg tossing in the seaconditions that aretypical of the NorthAtlantic seemed fool-

hardy. Ice Patrol sought a better way to deliver therequired thermal shock: bombing.

During and after World War II there weretremendous advances in the manufacture of“shaped” charges and special bomb and rocketdesigns. In 1959 Ice Patrol obtained 20 aircraftincendiary bomb clusters and conducted a series ofbombing experiments against several icebergs nearNewfoundland. Two types of incendiary bombswere tested, each consisting of many bomblets con-taining material, including thermite, thatburned at very high temperatures. The airplanedelivering the bombs was the USCG UF2GAlbatross, a twin-engine amphibious airplane.While there was some modest evidence of success

Figure 3: Drilling a hole in the iceberg with a power augerwas a 45-minute procedure during the 1960 tests.

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authorities, including personal approval fromNewfoundland’s Premier.

For each detonation, a team boarded the icebergfrom a rubber raft, drilled holes in the iceberg witha power auger, and planted the charges. Drillingeach hole took about 45 minutes, during which timeloud cracking noises could be heard from within

the ice. After planting the charges, the party ran adetonation cable to USCG Cutter Evergreen, whichignited the thermite. The first detonation, consist-ing of 196 pounds of thermite, scattered a shower ofmolten iron over a radius of 100 yards but, otherthan producing a few growlers, had no significantimpact on the size of the iceberg. The second deto-nation, on a different iceberg, used 364 pounds ofthermite, with the same results as the first. A thirddetonation, a 560-pound thermite charge plantednear the base of the iceberg’s pinnacle, had the fol-lowing result:

against one of the icebergs that had beenstruck eight times, the bomb clusters werenot able to deliver the concentrated heatsource required by Barnes’ thermal stresstheory of ice demolition.10

The following year, 1960, brought threeseparate demolition tests: bombing withexplosive charges, igniting thermite insidean iceberg, and coating an iceberg with car-bon black to accelerate natural, solar deterioration(Figures 2–5).

The bombing tests were a direct follow-on to thoseconducted in 1959, except that high-explosivebombs were used. Ice Patrol obtained 20 1,000-pound bombs from the U.S. Navy, 10 general-pur-pose bombs and 10 semi-armor-piercing bombs.Over an eight-day period(May 23–30), an Albatrossdropped all 20 bombs on asingle large iceberg usingthe same bombsight designfrom the previous year andwith the same outstandingsuccess. Of the 20 bombsdropped, 18 struck the ice-berg, of which three wereunderwater bursts and threefailed to detonate. Some ofthe bomb strikes resulted ina spray of ice fragments thatrose to over 500 ft. Otherscaused minor changes to theiceberg’s waterline orienta-tion due to a loss of icemass. At the conclusion ofthe bombing, Ice Patrol esti-mated that the iceberg’s sizehad been reduced by aquarter to a third but couldnot say for certain howmuch of the disintegration was due to bombing andhow much was due to natural deteriorationprocesses.11

The second phase of the 1960 tests was essentially arepeat of Barnes’ thermal shock experiments usingthermite. Led by project officer Lt. Cmdr. BobDinsmore, an Ice Patrol field party conducted threethermite detonations on June 8 on two icebergs inthe protected waters of Bonavista Bay. Because thetest was conducted in Canadian territorial waters,Ice Patrol obtained the full support of Canadian

Figure 4: Shortly after the detonation of 560 pounds of thermite during the 1960tests, a large plume of smoke and steam rose hundreds of feet into the air.

“…a magnificent display took place assmoke and molten iron was hurledhundreds of feet into the air, but theberg remained virtually unchanged.This concluded the thermite tests.”

Proceedings Spring 200554

“…a magnificent display took place as smoke andmolten iron was hurled hundreds of feet into the air,but the berg remained virtually unchanged. Thisconcluded the thermite tests.”12

These tests showed that thermite detonationswould not necessarily cause the disintegration seenin Barnes’ experiments in 1926.

The intent of the final phase of the 1960 tests was tocover an iceberg with carbon black and other darksubstances to speed its solar-induced deterioration.Three persons boarded the iceberg and in 30 minutes

spread 25 pounds of carbon black with fiberbrooms. They covered 6,500 square feet,which was approximately half the iceberg’ssurface. Five hours after the carbon blackwas placed on the iceberg, it broke apart,and by the next day it was reduced to lessthan a third its previous size. As with thebombing and wrecking mine tests, it is notpossible to say how much of the observedbreakup was due to natural causes andhow much to Ice Patrol’s intervention.

The tests in 1959 and 1960 can be best besummarized as follows:

“Although some damage to the bergsresulted, it must be admitted that all of themeans tried were unsuccessful in destroy-ing the icebergs.”13

ConclusionThe 1960 tests ended Ice Patrol’s attempts at icebergdemolition. Rather than destroying icebergs, IcePatrol adopted Tampa’s May 1926 approach, moni-toring the dangerous icebergs and warningmariners of their location. There are several reasonswhy this practice makes good sense. The demoli-tion process is expensive and dangerous. Even if aniceberg could be broken into smaller pieces, theresult would be an increase in the number of ice-bergs. They would be smaller than the parent ice-berg and, thus, harder for mariners to detect withtheir surface radars.

Endnotes1 Rodman, H. Report of Ice and Ice Movements in the North Atlantic Ocean. U. S. Hydrographic Office, Rpt No. 93, 26 p.

1890.2 International Ice Patrol, Reports of Vessels on Ice Patrol in the North Atlantic Ocean, April, May, June 1913, Revenue

Cutter Service Bulletin No. 1, 25 p. 1913.3 International Ice Patrol, International Ice Observation and Ice Patrol Service in the North Atlantic Ocean, From February

to August 1914, Bulletin No. 3, 78 p. 1914.4 Alexander, D., Indestructible Icebergs. Mariners Weather Log. Vol. 45 (3): 4-7, December 2001.5 International Ice Patrol, International Ice Observation and Ice Patrol Service in the North Atlantic Ocean, Season of 1923,

Bulletin No. 11, 166 p. 1923.6 International Ice Patrol, International Ice Observation and Ice Patrol Service in the North Atlantic Ocean, Season of 1926,

Bulletin No. 5, 127 p. 1926.7 Barnes, H. T., Some Physical Properties of Icebergs and a Method for their Destruction. In: Proceedings of the Royal Society

of London, Series A, Vol. 114, May 1927, pp. 161-168. 1927.8 Ibid.9 Anonymous, Nautical Magazine, Vol. 117, Volume 8, p. 196. 1927.10 Budinger, T. F., R. P. Dinsmore, P. A. Morrill, and F. M. Soule, International Ice Observation and Ice Patrol Service in the

North Atlantic Ocean, Season of 1959, Bulletin No. 45. 154 p.1959.11 Bullard, R. P., R. P. Dinsmore, A. P. Franceschetti, P. A. Morrill, F. M. Soule, International Ice Observation and Ice Patrol

Service in the North Atlantic Ocean, Season of 1960, Bulletin No. 46. 114 p.1960. 12 Bullard, R. P., R. P. Dinsmore, A. P. Franceschetti, P. A. Morrill, F. M. Soule, International Ice Observation and Ice Patrol

Service in the North Atlantic Ocean, Season of 1960, Bulletin No. 46. 114 p.1960.13 Bullard, R. P., R. P. Dinsmore, A. P. Franceschetti, P. A. Morrill, F. M. Soule, International Ice Observation and Ice Patrol

Service in the North Atlantic Ocean, Season of 1960, Bulletin No. 46. 114 p.1960.

Figure 5: During the 1960 tests, it took three men using fiberbrooms about 30 minutes to cover half the iceberg's surface withcarbon black.