ProPublica is going with flawed Stopgap:
Capable addition or flawed stopgap?
I vote for both. Flawed, yes apparently. But if the US wanted a stopgap where the money spent would go to US company then Aiviq was only option. I wonder how much uscg talked with the Australia Antarctica Program about the Aiviqs nearly 2 years breaking ice down there?
China has four active icebreakers and two more in construction. russia has 40 Arctic class icebreakers, 8 of them nuclear powered. Yeah, it’s about time for US to do something.
While Aiviq certainly has its flaws, using its non-compliance with the Polar Code seems rather petty since the same can be said about USCG’s existing medium and heavy icebreakers.
Didn’t know about the detail of the non-compliance of the CG breakers.
I didn’t think the article did a very good job of explaining why the CG thought the Aiviq is unsuitable.
The Aiviq is essentially an ice capable AHTS is it not? I can imagine why that’s a poor match for the CG but I’d like to see it spelled out.
Well, it’s the lowest of the low-hanging fruits: fuel oil in double bottom.
While Aiviq is an icebreaking AHTS by design, it is also classified as an icebreaker by the ABS. It’s certainly not as good as a purpose-built USCG icebreaker, but with Polar Star limited to Operation Deep Freeze and Healy being just one ship, it could still be “good enough” and enable the USCG to do “something” in ice-covered waters even as it is now, let alone after further conversion work.
I look forward to the USCG letting us know what they think of Storis once they come back from their first deployment in ice-covered waters.
The below article gives a description of the Aiviqs 2 years of exploits in Antarctica for the Australian Antarctica Program. It’s the only ice capable ship mentioned in the article that didn’t have an accident or mechanical failure. Good for the USCG that the Aiviq visited all 3 of Australians Antarctica bases including remote Mawson. If the USCG didn’t have anyone on board during any of those trips to check her ice breaking abilities hopefully they went over the logs with a fine toothed comb before purchasing to know what to fix during the long shipyard period.
I wonder how soft the ice was in the middle of the Austral summer. Aiviq has some inherent problems that will only manifest themselves in more challenging ice conditions. For example, its nozzles are susceptible to clogging.
Regarding @Alex63’s earlier post, here’s a good summary of China’s icebreaking fleet:
Couldn’t agree more, better something than nothing.
Few more comments on the ProPublica article:
Its direct-drive propulsion system was both less efficient and more likely to get jammed up in ice than the diesel-electric systems the Coast Guard used.
While Aiviq’s geared diesel-mechanical propulsion is certainly less suitable for icebreaking, one thing that it isn’t compared to diesel-electric drive is “less efficient”. Mechanical losses are much lower than electrical ones.
“I mean, on paper it’s an icebreaker,” Adm. Paul Zukunft, the then-commandant of the Coast Guard, told Congress in 2017. “But it hasn’t demonstrated an ability to break ice.”
Wait until they find out the same applies to the future Polar Security Cutters…
Even then, it wouldn’t be able to move forward through ice thicker than about 4.5 feet.
Given that the USCG acquired Aiviq specifically as a medium icebreaker, which by their own definition refers to an ability to break 4.5 ft ice in a continuous motion, the statement feels a bit… odd. They were not shopping for a heavy polar icebreaker this time.
In case I didn’t mention it earlier, I’d like to emphasize that I’m not a fan of Aiviq. I saw it in Alaska in 2012, didn’t really like it then and don’t really like it now. However, I also don’t like the way they try to come up with additional flaws in the article as if the ones Aiviq has previously demonstrated are not enough…
Can you explain that? Wouldn’t diesel-electric be more efficient due to the ability to add and remove engines as load dictates? Versus direct drive where you necessarily have to run the engine coupled to the shaft needed no matter the load?
By default, mechanical drivetrain certainly has fewer “sweet spots” in terms of optimal main engine load; in case of Aiviq there must be either two or four engines running when operating in ice as you have to keep both shafts turning.
However, you have to push the engines pretty far off their optimal load level to offset the ~10% conversion losses of a typical diesel-electric drivetrain. For example, the specific fuel consumption curve of a Wärtsilä 31 series medium-speed engine tuned for mechanical propulsion with controllable pitch propeller is so flat that the relative difference to the optimal loading point is less than that through most of the load range.
Some of those conversion losses can be recovered by using azimuthing propulsion which may provide somewhat higher hydrodynamic efficiency. However, the main reason why diesel-electric propulsion has been favored in icebreakers since the 1930s is the torque capability of the electric propulsion motors. In fact, the only prime movers that have similar characteristics are the ones they replaced: reciprocating steam engines.
Of course, over the years a small number of icebreakers have been built with geared mechanical propulsion. In case of Aiviq, the reason was that it was built firstly as an AHTS and secondly as an icebreaker. It’s biggest Achilles’ heel is the lack of specialized systems to offset the negative aspects of mechanical propulsion, namely “ice flywheels” to increase shaftline inertia to resist propeller-ice interaction and enable quick flushing of clogged nozzles.
2 posts were split to a new topic: Uncharted rock reef off the coast of Mawson
That’s a very interesting post.
Along with the Aiviq’s less-capable ice-breaking the CG apparently also had other, more general objections.
This is from Wikipeida:
USCG repeatedly turned down Hunter’s continued proposals, citing the vessel’s unsuitability for military operations and being less-capable than USCGC Healy ,
The position of the helo deck (fwd rather then aft) is mentioned but I was wondering specifically what other issues there were.
It makes little difference what the issues were. The USCG was told to buy it money talks no matter any faults.
Canadian Coast Guard has three converted AHTS that is classed as Medium Icebreakers:
They have has been in used as icebreakers in Canada for some years. Although not identical to Aiviq there may be some lessons to be learnt from how these three were converted and have performed.
Specifications as AHTS: MS «Balder Viking»
As converted: https://inter-l03.dfo-mpo.gc.ca/fdat/vessels/2424
Fantastic photo of “CCGS Jean Goodwill”
Photo: Vernon Buckle
Not sure what’s there to learn. Different ships, different extent of conversion, different operator.
Some of these icebreakers were chartered for icebreaking in the Baltic Sea. Here’s a video of two of them stuck with the ships they were supposed to assist, waiting for a more a capable icebreaker to arrive in the area:
However, from what I have heard, the Canadians have been quite content with them.
The icebreaking capability of Tor Viking II is 1.2 m thick level ice. I believe she is supposed to handle 1.0 m ice at 3.0 knots. Back when Shell chartered it for their Alaskan drilling hopes I spent a little time on her…Nice ship and very capable crew.
I also did a short transit on the Aiviq on their way to Alaska. As I recall her design parameters were similar.
The attached POAC paper about the ship’s ice trials has additional information about the Viking trio. The oversized flywheels and the fast pitch control mechanism enable quick flushing of the propeller nozzles if they are clogged by ice.
POAC01_V2_p849.pdf (1.7 MB)