[QUOTE=Tups;177816]tugsailor, most “offshore icebreakers” have nozzles. Even the Swedish icebreaking phenomenon Oden features a similar propulsion system as Aiviq. However, nozzles are known to cause problems (clogging) even in diesel-electric Z-drive ships like Fennica and Nordica, so there’s a definite loss of overall operational capability in difficult ice conditions especially for conventional shaftline ships that cannot “blow” the nozzles open. This is apparent with Oden when she’s being used for escort operations in the Baltic Sea - despite her fame as one of the best icebreakers in the world, she’s better off in operations such as the McMurdo break-in and scientific stuff in the Arctic than cutting icebound ships free on the Swedish coast.
As we all know, the advantage of nozzles is that the vessel has much higher bollard pull in open water for towing and anchor-handling operations. Unless you expect to do a lot of ice management and other challenging operations in difficult ice conditions, you’re better off with ducted propellers. However, in my opinion azimuth thrusters are something you can’t really do without if you want to do serious icebreaking. Perhaps that’s why ECO chose them for the two icebreaking AHTS vessels that it was (is?) building…
As for the icebreaking performance, it’s possible to calculate a rough estimate based on publicly available technical data and a few drawings from Shell’s ice management plan. I might actually have my students use Aiviq in their weekly exercises later this spring. Also, being a new design, it has probably been tested in an ice tank. I would expect that Shell has asked to see the model test report before paying for the vessel.
I, for one, would have wanted to see Aiviq break some ice. When I was up there in 2012, the ice around Kulluk was barely thick enough to walk on.[/QUOTE]
I stand corrected and certainly defer to your expertise on icebreakers.
AIVIQ was so thoroughly discredited by its becoming disabled due to basic design and construction deficiencies during the KULLUK tow, and it’s role in putting KULLUK on the rocks — which became the total constructive loss of the only proven ice capable oil rig available — that it became difficult to say anything good about AIVIQ.
To be fair to AIVIQ — KULLUK on the rocks — occurred most because AIVIQ was incompetently crewed, handled, and managed by Chouest, Shell, and the USCG Incident Command team.
This not only destroyed KULLUK, it also ushered in a U.S. Arctic drilling regulatory regime that was designed to strangle Arctic drilling for the foreseeable future.
It appears that Shell permanently lost confidence in AIVIQ after the loss of KULLUK, but could not admit it. Instead of dispatching AIVIQ to other tasks somewhere in the world where it could prove it’s worth, they kept her tied to the dock for two years where she could not get into any trouble. When Shell returned to the Arctic in 2015, they did not trust AIVIQ to tow the rigs.
As Drillbill pointed out, it appears that Shell was too afraid of another AIVIQ incident to really try her out, and to let her prove herself.
Now she sits at the dock in Seattle again with nothing to do, except to be disposed of.
If Shell had been smart, which it clearly wasn’t, they would have found a way to prove AIVIQ’s capabilities somewhere else in the world under competent management, with a new name and paint job, and they would have washed off most of the taint of the KULUK on the rocks incident before the 2015 drilling season.
