Surviving the Arctic: Polar Class Icebreakers

1.0 Introduction

Of the 93 major icebreakers in the world, only 13 traveled to the North Pole. Less than 14%! Breaking the ice is easy enough. But to reach the most hostile and remote regions of our planet, it takes more than a strong hull. We need ships specially adapted for these remote regions. A polar class ship holds extra surprises.

2.0 Old Ice

The average person rates strength of ice based on its thickness. But with polar regions, you also consider the age of the ice. In the majority of the world, ice forms each winter and completely melts by summer. But in the polar regions, ice endures multiple years. (Figure 2‑1) This multi-year ice gets stronger.

Figure 2‑1: Multi Year Ice [1]

Conventional sea ice forms from salt water, and the salt weakens the ice. But if that ice lasts multiple years, the cycle of partial melting and refreezing flushes the salt out of the ice. We now get solid, fresh water ice. Much stronger and harder for an icebreaker. Traveling to polar regions, you need to consider the thickness and age of the ice.

3.0 Extra Power

Extra ice demands extra power. The icebreaker needs a larger size to break through thicker and stronger ice. And it needs more space for extra facilities. This all adds to extra power. A LOT of extra power. The Mackinaw (WAGB-83) was a 1944 icebreaker that served on Lake Michigan. It only required 7.5 MW (10,000 hp) to continuously break 0.75 m (2.5 ft) of ice. [2] Compare that to the Healy (WAGB-20), which continuously breaks 1.4 m (4.5 ft) of ice, with 34.5 MW (46,350 hp) of power. [3] Over four times the power needed for operation in polar regions.

And the Healy isn’t the largest. Russia created an entire fleet of nuclear powered icebreakers! The Project 22220 class of icebreakers come with two nuclear reactors, producing a total of 350 MW of thermal power, with 60 MW delivered to the propulsion shafts! [5] That provides plenty of power to spare.

Figure 3‑2: Project 22220 Icebreaker [6]

4.0 Heating

All that power goes to more than just propulsion. We also need it for heating. With polar temperatures dropping down to -60C, heating is no trivial task. [7] And it goes beyond heating the vessel interior. Remember, these ships are made of steel, which is very good at conducting heat (or in this case, the lack of heat). People might simply rest their hand on a steel handrail and get stuck. Your hand instantly freezes to the steel. To prevent this, we run heated steam through the handrails, under the decks, around any exterior machinery. Considering external heating, ask yourself: do I want this device to ever move again? If so, we probably need to heat it on a polar class icebreaker.

Heating also ties into ship safety. During a storm, waves break over the bow, spraying the deck and quickly freezing. This builds up, forming thick layers of ice. Across the entire surface of the ship, only a few centimeters of ice add up to over 100 MT of extra weight. Frequently, this builds on just one side, heeling the ship over. Left unchecked, the ice buildup may capsize the vessel within mere hours. We need an option to quickly break up the ice and remove it. Hence the heated exterior. It’s much harder for ice to build up against metal constantly melting it.

4.1 Nuclear Heating

Considering the heating, nuclear icebreakers make a lot of sense. Only a small portion of the heat generated by a nuclear reactor converts into rotating shaft power. The steam cycle that drives this is not very efficient, resulting in megawatts of left-over heat that we need to remove. Easiest option, dump the extra steam straight into the ocean. (This steam is free from radiation and never enters the reactor.) But if we already have the steam, no need to be stingy with it. Pipe it throughout the vessel and use it everywhere. Steam turns into unlimited fresh water. Heated swimming pool. Steam sauna. Steam nozzles to clear away the deck. I bet the crew enjoy endless hot showers on those nuclear icebreakers.

5.0 Remote Operation

One of the biggest challenges for polar operations: the remote location. You find yourself far away from ANYTHING. Beyond normal radio communication (VHF). Beyond the operating range of regular coast guard. Traveling into waters that search and rescue can’t enter. As a polar class icebreaker, you are already the biggest, baddest ship in the region.

If you get in trouble, we can’t find anyone better equipped. You’re it. A polar vessel needs facilities for self-rescue. This includes extended machine shops to build any component on the ship. Storage rooms packed with spare components. Even spare propeller blades. Most polar class icebreakers include a full set of spare propeller blades, sufficient to replace an entire propeller. And a crane to move those blades and lower them over the side. Plus divers trained to replace the blades in freezing cold water. If I look long enough, I can even find a spare piston head somewhere in the storage closet. Polar icebreakers prepare to fix anything. When trouble calls, a polar icebreaker provides its own rescue.

Remote operation also includes less dependence on communication. A typical cargo ship checks their position from GPS satellites every few minutes; they receive daily updates on weather predictions for the region; and a daily check in with home base concerning resupply and coordination. All those features become less reliable in polar waters. GPS and satellite communication experience sparse reception, since fewer satellites orbit our poles. No more daily weather updates. Hence, many polar icebreakers include helicopter support. This provides the ability to fly around and scout out the best ice route. Without satellite assistance, we provide our own navigation guidance.

Traditional navigation also encounters challenges. Outside of GPS, a ship may have magnetic and gyro compasses to detect their direction. But magnetic compasses depend on the alignment of the Earth’s magnetic field. Near the North and South poles, that magnetic field isn’t always consistent. And the gyro compass uses a rotating gyroscope to align with the Earth’s rotation axis. Except, at the poles, you land on top of the axis of rotation. Makes it a lot harder to determine direction. Clearly, we found methods to compensate. It just shows that at the Polar regions, the simplest things become unexpectedly challenging.

6.0 Getting Stuck

One unexpected challenge: getting stuck. It’s possible. The ice constantly shifts and moves, closing the channel behind you. In the frigid heart of winter, the ice may build behind you; gaining thickness until the icebreaker can’t crack it.

First, make sure the ice doesn’t crush you. Figure 6‑1 shows a cross section of the Mackinaw (WAGB-83) hull. Notice there are no vertical surfaces on the hull. Every section has a slope and curve to it. If the ice pushes in from the side, that force gets redirected to push upwards on the hull. This is how icebreakers ride up on top of the ice. It’s unlikely the ice would completely push the icebreaker out of the water, but this hull shape acts like a safety valve. It limits the maximum pressure on the hull.

Figure 6‑1: Ship Section View [8]

Now it turns into a waiting game. Nothing to do but hold position until spring thins out the ice. Polar class icebreakers deploy with huge fuel and food reserves. In the case of nuclear icebreakers, they can go years without refueling. Depending on distance, the helicopter also serves to evacuate nonessential personnel to a rescue ship waiting outside the ice field. And, of course, entertainment to stay sane during the endless waiting. Polar icebreakers don’t survive when trapped in an ice field; they thrive.

7.0 Conclusion

The Polar regions of our planet are not pleasant. They demand uncompromising strength, vast reserves of energy, and flexibility to adapt with each challenge. To meet these demand, Polar class icebreakers go beyond anything we expect for a normal ship. These miracles of endurance share more kinship with a spacecraft than a cargo ship. They voyage into vast desolate regions, meet the harshest fury on our planet, and return the crew home safe.

8.0 References

[1]	Frontier Scientists, “First Year or Multi Year Ice,” YouTube, 25 Nov 2015. [Online]. Available: https://youtu.be/pDuSk8G0GkU. [Accessed 14 Mar 2023].
[2]	US Coast Guard, “Mackinaw, 1944 (WAG-83),” United States Coast Guard, 10 Feb 2021. [Online]. Available: https://www.history.uscg.mil/Browse-by-Topic/Assets/Water/All/Article/2500580/mackinaw-1944-wag-83/. [Accessed 14 Mar 2023].
[3]	Wikipedia Authors, “USCGC Healy (WAGB-20),” Wikipedia, 25 Feb 2023. [Online]. Available: https://en.wikipedia.org/wiki/USCGC_Healy_(WAGB-20). [Accessed 14 Mar 2023].
[4]	US Coast Guard, “USCGC Healy (WAGB-20) north of Alaska,” Wikimedia Commons, 2 Jul 2007. [Online]. Available: https://commons.wikimedia.org/wiki/File:USCGC_Healy_(WAGB-20)_north_of_Alaska.jpg. [Accessed 14 Mar 2023].
[5]	Wikipedia Authors, “Project 22220 icebreaker,” Wikipedia, [Online]. Available: https://en.wikipedia.org/wiki/Project_22220_icebreaker. [Accessed 17 Feb 2023].
[6]	Naval News, “Russian Project 22220 icebreaker Arktika starts trials after repairs,” Naval News November 2021 Navy Forces Maritime Defense Industry, 26 Nov 2021. [Online]. Available: https://www.navyrecognition.com/index.php/naval-news/naval-news-archive/2021/november/11061-russian-project-22220-icebreaker-arktika-starts-trials-after-repairs.html. [Accessed 17 Feb 2023].
[7]	Poseidon Expeditions, “Temperature in the Arctic Circle,” Poseidon Expeditions, [Online]. Available: https://poseidonexpeditions.com/about/articles/temperature-in-arctic-circle/. [Accessed 14 Mar 2023].
[8]	J. G. German, “Design and Construction of Icebreakers,” Transactions of SNAME, pp. 26-69, 1959.
[9]	S. L. Planisek, Icebreaker Mackinaw, 2nd. Edition, Mackinaw City, MI: Great Lakes Lighthouse Keepers Association, 2008.
[10]	US Coast Guard, “Major Icebreakers of the World, Explanatory Piece,” USCG office of Waterways and Ocean Policy, Washgington, D.C., USA, 2017.
[11]	D. Klimensky, “Instant vapor – Boiling water freezes instantly in Siberia,” YouTube, 13 Dec 2012. [Online]. Available: https://youtu.be/jKMNSvpB9dY. [Accessed 14 Mar 2023].
[12]	Wikipedia Authors, “Crocus-p1020491,” Wikimedia Commons, 9 Nov 2005. [Online]. Available: https://commons.wikimedia.org/wiki/File:Crocus-p1020491.jpg. [Accessed 14 Mar 2023].
[13]	Our Fair, “Think Arctic! – A Very Special Award for 2015,” Connecticut Science & Engineering Fair, 4 Oct 2014. [Online]. Available: https://ctsciencefair.org/2014/think-arctic-a-very-special-award-for-2015. [Accessed 14 Mar 2023].

Surviving the Arctic: Polar Class Icebreakers

1.0 Introduction

2.0 Old Ice

3.0 Extra Power

4.0 Heating

4.1 Nuclear Heating

5.0 Remote Operation

6.0 Getting Stuck

7.0 Conclusion

8.0 References

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