Arctic Ice Navigation: Ice Types and Phenomena (Part 2 of 3)

Photos from "Illustrated Glossary of Snow and Ice."
Photos from “Illustrated Glossary of Snow and Ice.”

For 19th century Arctic explorers, ice in various forms was a potential hazard to navigation and to life. For this reason, identification, interpretation, and avoidance of ship-damaging ice were important skills. Because of his firsthand encounters with threatening ice, Isaac Israel Hayes, M.D. dedicated a ten-page chapter on “Melville Bay pack” ice navigation in The Land of Desolation. [1]

Well before reaching the Greenland coast, 19th century explorers potentially encountered storms, fog, icebergs on the Grand Banks of Newfoundland or the comparatively shallow underwater plateaus off the Avalon Peninsula. Mariners leaving Boston via Nova Scotia routinely followed established sea routes off Cape Race, Newfoundland. This was the most direct route to Cape Farewell, Greenland and to so-called areas of “middle ice” and iceberg-cluttered “North Waters” traversed by whalers and Arctic explorers.

Inside cover of "Illustrated Glossary of Snow and Ice," signed by W.F. Weeks, renowned ice scientist and author of "On Sea Ice."
Inside cover of “Illustrated Glossary of Snow and Ice,” signed by W.F. Weeks, renowned ice scientist and author of “On Sea Ice.”

Icebergs
Calved from glaciers, icebergs are extremely hard ice and are historically ship killers. Melting or disintegrating fragments are often of a greater danger since they are not readily visible during watchstanding and/or in heavy seas. Two primary types of hazardous iceberg remnants are described as follows [2]:

Growlers – are transparent, green to dirty black ice fragments that extend about three feet above the ocean surface and are roughly 15 feet in diameter. They are of adequate mass to cause ship damage, especially to small craft, such as wooden sailing vessels. At times, the presence of a growler can be detected when an ocean wave breaks over the bobbing ice, causing a plume of windblown sea spray.

Bergy Bits – are larger ice fragments that can be seen visually to avoid impact. They are often smooth or rounded from continual wave action. [3] They extend about 10 to 20 feet above the ocean surface, with an overall length of 20 to 45 feet. Unseen dangers are hull-tearing underwater projections that can extend several times the apparent height, and for this reason, they should be given a wide berth.

Beyond these two categories, icebergs can be described as small, medium, and massively large, and by their apparent shape: pinnacled, tabular, wedge, or block. They are guided by prevailing ocean currents. Growlers and bergy bits, however, are driven by wind and waves, potentially complicating the transit of ice-strewn waters. Because of their immense size and keel depth, icebergs can run aground, roll, and break apart with tremendous noise, hissing spray, and with surging ice fragment-filled waves, an event best witnessed at distance. Near Upernavik, Greenland, Hayes described a large fracturing iceberg:

A loud report first startled us; another and another followed in quick succession, until the noise grew deafening, and the whole air seemed a reservoir of frightful sound. The opposite side of the berg had split off, piece after piece, tumbling a vast volume of ice into the sea, and sending the berg revolving back upon us. This time the movement was quicker; fragments began again to fall; and, already sufficiently by the alarming dissolution which had taken place… [4]

Sea Ice
Sea ice is frozen seawater and can vary from matte-like grease ice, young ice, pack ice to tumultuous ice hummocks and ridges. Ice can open to form floes and transient leads, some miles in length that can close or “nip” unexpectedly from far-reaching action of wind, tide, and waves. Sea ice can be mixed with ice originating from icebergs. Because of comparatively smaller size, growlers and bergy bits can originate from massive sections of sea ice (a “floeberg”) and/or hummocked ice. [5]

Sea ice is neither passive nor quiet even amidst deep Arctic winters. The movement of sea ice can exert tremendous pressure force and upheaval against other ice, inflicting significant damage to 19th century ships and boats. Once beset in ice, the ship will go – and oft times destructively – where the ice goes. Coupled with heavy winds and freezing spray, Arctic gales can strengthen the destructive force of sea ice. At the northern reaches of Greenland, near Northumberland Island, Hayes described the damaging “nipping” pressure of sea ice in An Arctic Boat Journey:

With the temperature at 22º, and falling…time after time were the boats thrust into the leads, — into the very jaws of the grinding ice, and as often were they forced back. Tired and defeated, our boats badly battered, the Ironsides deeply dented along her water-line, the [whaleboat] Hope nearly crushed, and leaking badly, we could only avail ourselves of the change of tide, and work slowly down the shore through the lead which it opened. [6]

Water Sky
This phenomenon is essentially the counter finding to an ice blink. The darkness reflected on bases of white clouds can indicate presence of open water or large floes adjacent to at or the terminus of an icepack. Through his observations, Hayes provided an explanation for this cloud-darkening reflection:

A broad crack, starting from the middle of the bay, stretched over the sea, and uniting with other cracks as it meandered to the eastward, it expanded as the delta of some mighty river discharging into the ocean, and under a water-sky, which hung upon the northern and eastern horizon, it was lost in the open sea. [7] 

Ice Blink
The reflection of white ice on the bases of dark clouds indicates an approaching icepack. This phenomenon was observed and utilized by 19th century Arctic explorers. In The Open Polar Sea, Hayes made several references to an “ice-blink,” to include: “Sure enough the pack was there, as was soon evidenced by an ‘ice-blink,’ and in a little while we were close upon it.” [8]

During the 19th century, ice navigation in Arctic regions presented numerous challenges and dangers, including the loss of ships and lives. These explorers navigated changing ice conditions in retrofitted sailing vessels and developed skills from daunting experiences that enabled them to avoid and/or negotiate potentially damaging ice. By persevering harsh weather and sea conditions, they returned from High Arctic expeditions, recording their rich experiences and expanding scientific knowledge of the era. The final segment, “Part 3” will discuss over-wintering ship preparations.

Notes:
1. The Land of Desolation, Isaac Israel Hayes, M.D., Sampson Low, Marston, Low, and Searle, 1871, 222-231.

2. Ice Navigation in Canadian Waters, Chapter 3: “Ice Climatology and Environmental Conditions,” 2012, 43-47.

3. Illustrated Glossary of Snow and Ice, Terence Armstrong, et al, Scott Polar Research Institute, Cambridge, 1966, Fig. 34.

4. The Open Polar Sea, Isaac Israel Hayes, M.D., Hurd and Hourghton, 1867, 49.

5. Glossary of Oceanographic Terms, 2nd ed., B. B. Baker, Jr., et al, U.S. Naval Oceanographic Office, 1966, 21.

6. An Arctic Boat Journey, Isaac Israel Hayes, M.D., James R. Osgood and Co., 1871, 133.

7. Hayes, 1867, 348-349.

8. Hayes, 1867, 441.

Social profiles