results were "just as effective as if we had stormed the Rock of Gibrahar." It had become evident 

 that the small guns on the early patrol vessels were no match for the icebergs they were charged 

 with tracking. The practice of shooting at icebergs with the various weapons on the patrol vessels 

 has continued throughout Ice Patrol's history, but these efforts were undertaken in the name of 

 gunnery practice rather than serious attempts at iceberg demolition. 



Mines 



One of the little-known responsibilities of the Revenue Cutter Service in the early 1 900s 

 was the destruction of derelict vessels drifting in the ocean."* Abandoned wooden vessels could 

 drift for many years, circumnavigating the North Atlantic Ocean several times and creating a 

 great hazard to navigation. Their destruction was usually accomplished using standard Navy-type 

 wrecking mines, which had guncotton as the explosive agent and were detonated using an 

 electrical charge from a battery. The Ice Patrol vessels conducted this important Coast Guard 

 mission and carried the wrecking mines, so it was natural to see if they would fare any better than 

 the gunshots against the icebergs. 



In May 1923, USCGC Tampa tracked a particularly fast-moving iceberg in the warm 

 (>15° C) Gulf Stream waters south of the Tail of the Banks. Since this iceberg was well into the 

 busy steamer lanes and considered particularly menacing, they decided to use wrecking mines to 

 hasten its demise. The effort was done mostly in the name of experimentation, but the iceberg's 

 location imparted an operational urgency to the destruction of this iceberg. 



From 20 to 24 May, Tampa exploded four charges at depths ranging from 6 to 30 feet 

 along the underwater portion of the iceberg. The first attempt consisted of suspending the mine 

 from a float and allowing it to drift toward the iceberg with the hope of detonating it as it came up 

 against the side of the iceberg. However, the flow of the water carried the mine past the iceberg. 

 The mine was retrieved, placed over a subsurface ledge of the iceberg, and exploded. The 

 remainder of the attempts, conducted in very calm sea conditions, involved attaching the mines to 

 the iceberg using lines with grapnels. This allowed the mines to explode right alongside the 

 iceberg at various depths. The explosions produced much loose ice and calved many growlers. 

 Overall, Tampa considered the experiment a success, the crew believing that they had shortened 

 the iceberg's life by one to two days — an important achievement considering the dangerous 

 location of the iceberg. Before it completely melted on 25 May, this iceberg reached 39°08'N, 

 which at that time was the lowest latitude attained by an iceberg since the establishment of the 

 International Ice Patrol. It was clear that the effective use of wrecking mines, while successful in 

 this case, could be undertaken only in conditions calm enough for small boat operations and in 

 warm water, so natural deterioration processes and the explosives could work in concert to 

 destroy the iceberg. 



The experimental use of wrecking mines to demoUsh icebergs continued in 1924, with 

 three separate attempts, two by Tampa and one by Modoc.^ The experiments met with, at best, 

 fair success. 



On 28 May 1926, Tampa undertook the final effort to destroy icebergs using wrecking 

 mines. Tampa came upon a small to medium iceberg in the steamer lanes, again in the warm Gulf 

 Stream waters. Although natural deterioration processes were taking their toll on this dangerous 

 iceberg, Tampa used its 6-pounder gun and 238-pound wrecking mines to speed the decay. They 

 concluded: "Considerable ice was shaken down but it is questionable whether the expenditure 

 would be justifiable in continuing the practice on a greater scale." That evening Tampa remained 

 close to the iceberg, "warning all approaching ships of its locafion." 



45 



