The following is a news release quoted in full. Frankly I think it is a good thing that we are reporting the problems rather than just happy news. The public and our law makers in particular need to understand that we are putting people, and the mission, in danger because we are making do with overage systems that should have been replaced long ago. Incidentally, USAP is apparently U.S. Antarctic Program.
This additional note was attached to the release, “Editor’s Note: All dates and times are in New Zealand Daylight Time, which is 21 hours ahead of Pacific Standard Time and 24 hours ahead of Eastern Standard Time. Video of the Cutter Polar Star’s operations are available by clicking the thumbnails above or clicking here and here. Photos from the cutter’s operations by clicking the thumbnails above or clicking here. ”
MCMURDO STATION, Antarctica – The crew of U.S. Coast Guard Cutter Polar Star completed their mission Tuesday in support of National Science Foundation (NSF) after cutting a resupply channel through 15 miles of Antarctic ice in the Ross Sea and escorting supply vessels to the continent.
The Polar Star sailed from Seattle to assist in the annual delivery of operating supplies and fuel for NSF research stations in Antarctica during Operation Deep Freeze by carving a navigable path through seasonal and multi-year ice sometimes as much as 10-feet thick. Operation Deep Freeze is the logistical support provided by the U.S. Armed Forces to the U.S. Antarctic Program.
“Although we had less ice this year than last year, we had several engineering challenges to overcome to get to the point where we could position ourselves to moor in McMurdo,” said Capt. Michael Davanzo, the commanding officer of the Polar Star. “Our arrival was delayed due to these challenges, but the crew and I are certainly excited to be here. It’s a unique opportunity for our crewmembers to visit the most remote continent in the world, and in many respects it makes the hard work worth it.”
On Jan. 16, Polar Star’s shaft seal failed causing flooding in the cutter’s engine room at a rate of approximately 20-gallons per minute. The crew responded quickly, using an emergency shaft seal to stop the flow of freezing, Antarctic water into the vessel. The crew was able dewater the engineering space and effect more permanent repairs to the seal to ensure the watertight integrity of the vessel. There were no injuries as a result of the malfunction.
Flooding was not the only engineering challenge the crew of Polar Star faced during their trek through the thick ice. On Jan. 11, their progress was slowed after the one of the cutter’s three main gas turbines failed. The crew uses the cutter’s main gas turbine power to breakup thick multi-year ice using its propellers. The crew was able to troubleshoot the turbine finding a programing issue between the engine and the cutter’s 1970s-era electrical system. The crew was able to continue their mission in the current ice conditions without the turbine.
“If the Polar Star were to suffer a catastrophic mechanical failure, the Nation would not be able to support heavy icebreaker missions like Operation Deep Freeze, and our Nation has no vessel capable of rescuing the crew if the icebreakers were to fail in the ice,” said Vice Adm. Fred Midgette, commander, U.S. Coast Guard Pacific Area in Alameda, California. “The crewmembers aboard Polar Star not only accomplished their mission, but they did so despite extreme weather and numerous engineering challenges. This is a testament to their dedication and devotion to duty.”
The cutter refueled at McMurdo Station Jan. 18 and continued to develop and maintain the ice channel in preparation for two resupply ships from U.S. Military Sealift Command, Ocean Giant and Maersk Peary. The crew of Polar Star escorted the vessels to the ice pier at McMurdo Station, an evolution that requires the cutter to travel about 300 yards in front of the supply ships to ensure they safely make it through the narrow ice channel. The crew escorted the Ocean Giant to the ice pier at McMurdo Jan. 27 and conducted their final escort of the Maersk Peary to Antarctica Feb. 2. The crew escorted Maersk Peary safely out of the ice Feb. 6 after supply vessel’s crew transferred their cargo.
The Polar Star departed their homeport in Seattle Nov. 30, 2017, and are expected to return to the U.S. in March 2018. The 399-foot Polar Star is the only operational heavy icebreaker in the U.S. fleet. The cutter, which was built more than 40 years ago, has a crew of nearly 150 people. It weighs (displaces–Chuck) 13,500 tons and uses 75,000 horsepower to break ice up to 21 feet thick.
The U.S. military is uniquely equipped to assist the National Science Foundation in accomplishing its USAP mission. This includes the coordination of strategic inter-theater airlift, tactical intra-theater airlift and airdrop, aeromedical evacuation support, search and rescue response, sealift, seaport access, bulk fuel supply, port cargo handling, and transportation requirements supporting the NSF, the lead agency for the USAP.
Chuck Hill's CG Blog 
RFP is expected later this month:
https://news.usni.org/2018/02/08/31241
Hopefully this time the Coast Guard will design an icebreaker with shaft bearings that don’t repeatedly fail, as they have done on the Polar Star and Polar Sea. The Russians and the Canadians, seem to know how to design this critical feature – maybe we should ask them for help.
How about Healy?
It does seem it exceeds our expectations for a “medium” icebreaker.
Healy is a good ship. Finns were deeply involved in the hull and propulsion design. For example, the shaftline design is based on that of the Russian nuclear-powered icebreaker Taymyr so I was wondering if they have had problems with the seals etc.
Given that the Healy has successfully performed Operation Deep Freeze, the CG should make sure that they use that shaft design – or another proven design – instead of trying to do it in house.
Or just not use shafts…
You are suggesting azimuth pod drives, correct? Have they ever been used on a heavy icebreaker, and if so, what is the reliability?
I don’t have the availability figures at hand, but when it comes to the VI series Azipods (the ice class ones), I’m fairly sure that even the prototype units have a better track record than the CP shaftlines on the Polars. The oldest pods from 1993 and 1994 (which have power equivalent to Healy’s shafts) are still in service in the Russian Arctic and I bet it’s the ships around them (1970s tankers) that expire first.
As for heaviness, the biggest icebreaking ship with Azipod propulsion is about 980 ft long, has about the same power as the Polars (45,000 kW), and breaks about 7 ft of ice when moving backwards with the pods facing the ice. Chuck posted about them a while back.
We do have some experience with Azipods on the Great Lakes icebreaker Mackinaw.
True, but the Mackinaw displaces 3500 tons and its pod is rated just over 9000 SHP. Are you really going to extrapolate that to a ship with 3 times the displacement and just under 3 times the SHP?
That’s the kind of thinking that produced the Polar Star and Polar Sea’s CPP design. I seem to remember someone saying this about this design:
“The Polar Class have always been “maintenance intensive” and a good part of the reason is the complexity of her nine engine propulsion system and her controlable pitch propellers (CPP).”
😉
Anonymouse, Always nice to know people actually read my stuff.
Its not like Mackinaw is the only icebreaker to have used Azipods. I am sure Tups has a better handle on the actual installations, but from what I have read it appears that they are now the norm for icebreakers.
Azipods look like a simpler system to me. If you just count the number of bearings exposed to direct impacts of the ice, the system appears more robust.
If you look at Polar Star, she has, I believe, two rudders (two bearings), three shafts (three bearings, total five), each shaft has a propeller with at least three variable pitch blades (I don’t really remember). Each blade has a bearing at its base, subject to shock of the ice acting through the lever of the propeller blade (nine bearings, total 14). Plus there are three sets of reduction gears that are also subject to shock.
By comparison, using azipods, the props are fixed pitch. There are only two primary bearing in each unit, a very large one that turns the entire unit, and the propeller bearing. If you use two Azipods there are four bearings and if you use three there are six.
Its a bit of a simplification, but that looks more reliable to me.
(See below for a correction on this count.)
Indeed, hardly anyone builds icebreakers with shaft lines in these days. The few exceptions are Russian nuclear-powered icebreakers and some research vessels with special requirements regarding underwater noise. Podded propusion is also excessively used in ships that operate stern-first, meaning that the propulsors are facing the incoming ice – this is something the shaft lines cannot do for a number of reasons, including increased risk of propeller blade damage. However, as always, the decision to use podded propulsion should be done on case-by-case basis: icebreakers are tailor-designed for the specific task they are intended to complete. However, if I were to start icebreaker design from scratch, I’d probably start from twin pods as that’s the most common configuration in these days.
As for the Polar Star, the vessel has three four-bladed propellers and a single centerline rudder. This used to be the standard configuration for large icebreakers, but many recent large icebreaking vessels (e.g. Healy and the new Australian research vessel) have twin shaft/twin rudder configuration. The only triple-shaft icebreakers built in recent years or under construction are, again, the largest Russian nuclear-powered icebreakers.
Azipod has had its fair share of teething problems, but it’s still the propulsion system of choice particularly in the eastern hemisphere. The largest icebreaking vessels ever built, the YamalMax LNG carriers, each have three 15-megawatt (20,000 hp) Azipod VI2300L propulsors.
New Russian Icebreaking Offshore Support Vessel. Relatively small but almost 20,000 HP. A medium icebreaker in terms of capability. Azipods. https://www.marinelink.com/news/sovcomflots-icebreaker433656
Few benchmarks:
– the most powerful icebreaker with azimuthing propulsion in service by total power: Polaris (3 pods, 19 MW/25,500 shp)
– the most powerful icebreaker with azimuthing propulsion in service by power per unit: Project 21900M, 3 ships in service (2 Steerprop thrusters, 18 MW/24,100 shp)
– the most powerful icebreaker with all-azimuthing propulsion under construction: Aker ARC 130 A (3 pods, 21.5 MW/29,000 shp)
– the most powerful icebreaker with hybrid propulsion under construction: Viktor Chernomyrdin (2 pods + 1 shaftline, 25 MW/33,500 shp)
So correcting my count of bearing subject to direct impact by the ice, The Polar Star has 16, one for the rudder, three for the shafts, and twelve for the controllable pitch propeller blades.
Gents, you missing the salient point about ship acquisiton:
The more detailed specs one puts into a rqmt, the MORE THE COST of the resultant ship.
And if the USCG specs a propulsion system which does NOT work, the taxpayers write the check to fix it?
OTOH, if the USCG requires a system which is in service and has a good record, there is much better chance of a reliable power plant.
I do note that there are more and more Axipods being put on ice ships. And if you break a pod, it is Much quicker to replace once the breaker RTBs that is~
I don’t know how the USCG is specifying things, but I’d expect that if profit-oriented commercial companies trust a COTS product ship after ship, its reliability should be on an acceptable level. It’s true that Azipods have baan around only for 25 years or so, but they have probably accumulated more running hours than USCG has on any of its icebreaker designs…
Soon!
https://www.fbo.gov/index?s=opportunity&mode=form&id=cbf44eb03381a0a9179e08bc15b40e25&tab=core&tabmode=list&=