Breaking Ice—Like A Hot Knife Through Butter

Over the past couple days, there have been several cancellations and delays in helicopter flights between ships due to surrounding fog and potential for ice to build up on the helicopter blades. Also, both Louis and Healy have had a couple moments caught in the ice, but both ships have been working together to keep things moving and data rolling in. While I am enjoying the company onboard, I don’t think anyone wants to be stuck in the Arctic Ocean!

For both ships to collect accurate data, we have been alternating positions with Louis in leading and breaking through the ice. Seismic data needs to be collected at a slow speed, but for the ship to break ice, it needs to move at a faster pace. Therefore it is beneficial for one ship to lead at a slightly faster pace when going through ice while the other ship follows at a slower speed to collect accurate data. In addition, both ships use sound systems and energy waves for data collection and the sound of ice breaking can interfere and alter the data. When Louis leads the path, that interference is reduced for Healy and vice versa. As I mentioned in a previous blog, Louis is using streamers and buoys that trail behind their ship to collect data, so using Healy’s guided path helps prevent them from getting caught in the ice.

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Audio description: As Louis and Healy pass each other one foggy afternoon, they discuss the weather conditions and request the activation of deck lights so they can have a clear visual of each other. This conversation is between Captain Frederick Sommer, who is the commanding officer of U.S. Coast Guard Cutter Healy, and Captain Mark Rothwell, who is the commanding officer of Canadian Coast Guard Ship Louis S. Saint Laurent.

When I first heard of an ice breaking ship, I thought they plowed through the ice by ramming straightforward into it. My assumption was wrong.

The ship’s weight and generated momentum are essential characteristics that make it an effective icebreaker. Healy generates a maximum of 30,000 horsepower with two shafts and Louis produces 27,000 horsepower with three shafts. The bows on both Healy and Louis are designed with an arch, much like a spoon, so they can ride up on top of the ice, pushing it down and out the sides of the ship. Both ships also have what is called an ice knife. This isn’t the type of knife you might immediately imagine. It is basically a projection of solid steel (or wedge) located below the bow that helps prevent the ship from riding too far up onto heavy ice and effectively beaching itself or having ice travel under the hull to the propellers.

Low friction inertia paint, which provides a slick surface, is used to coat the entire underwater portion of ice breaking ships up to a few feet above the waterline. This allows for a smoother transition through the ice, helps keep buildup such as seaweed off the ship, and allows the ship to use less energy and fuel. In addition, ice breaking ships are constructed with thicker hull plating and heavier “web” frames in the bow area. The distance between the frames is reduced in the bow and stern areas for added strength. There is also an ice horn, which is basically a block of steel under the stern and behind the rudders and is there to protect the rudder when the ship is backing up in ice.

Some differences do exist between Louis and Healy. For example, Healy has a bow wash system that draws water from under the ship and distributes it onto the ice through nozzles along the ship’s hull. As a result, the ice is flooded and it is easy for the ship to move forward. This is especially helpful when snow, which offers greater friction on the hull, is present. The water helps reduce the friction that would otherwise slow down the ship and its momentum.

Louis also has a unique feature known as a bubbler system. High pressure air is discharged through underwater nozzles, thus providing a lubricating film of water and air between the ice and the ship’s hull. Louis also has a water ballast heeling system. Water in the vessel’s port (left) and/or starboard (right) ballast tanks can be quickly transferred from tank to tank to make the ship rock and break free if it becomes stuck in the ice. It is used only occasionally, and, so far, not at all this trip.

More from the beautiful Arctic Ocean soon!

Jessica Robertson

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