“VT Halter releases more details of winning Polar Security Cutter design” –Marine Log

Marine Log provides some additional details on the specifications for the Polar Security Cutter (Heavy Polar Icebreaker) construction project, recently contracted to VT Halter.

Projected delivery dates, 2024, 2025, 2027.

  • Displacement, Full Load: 33,000 tons (later corrected to 22,900 tons–Chuck)
  • Length: 460 ft (140 meters)
  • Beam: 88 ft (26.8 meters)
  • HP: 45,200
  • Accommodations: 186
  • Endurance: 90 days

For comparison, USCGC Polar Star is:

  • Displacement: 13,623 long tons (13,842 t) (full)
  • Length: 399 ft (122 m)
  • Beam: 83 ft 6 in (25.45 m)
  • HP: (3 × 25,000 hp (19,000 kW))
  • Accommodations: 187

Thanks to Secundius for bringing this to my attention

32 thoughts on ““VT Halter releases more details of winning Polar Security Cutter design” –Marine Log

  1. It’s interesting how the article claims that “the ship design is an evolution from the mature Polar Stern II, currently in design and construction in Germany” while the Germans have yet to even select a shipyard to build their long-awaited polar research vessel.

    45,200 hp, assuming that’s the shaft power, would nearly tie the PSC with Canada’s proposed polar icebreaker for the title of the most powerful diesel-electric icebreaker in the world.

    • This was also both interesting and a little surprising. “The ship’s combat system will be derived from the Aegis Combat System, and the Coast Guard is still mulling over the weapons loadout, Schultz told reporters on Wednesday.”

  2. Unless my math is wrong USCGC Healy is already 34500 KW (46500 HP) and it is only rated as a medium breaker. Wondering if this is a “heavy icebreaker” in name only.

    • Your math is right but Healey does not have that much shaft horsepower because that is provided by two electric motors of 11.2 MW each for 22.4 MW total or 30,039 HP. The Coast Guard break point for classification as a heavy icebreaker is 40,000 shaft HP.

  3. I see that you’re quoted USCGC Polar Star as having 75,000 shp whereas other sources claim that the gas turbines are rated at “only” 60,000 shp in continuous operation. When I visited one of the ships a few years ago, I asked about this discrepancy because I thought there’s a switch that allows the operator to activate some kind of “afterburner” for a limited amount of time. How I understood their explanation is that this is an inherent feature of a gas turbine: if the shaft slows down for example due to propeller ice contact, the gas turbine will automatically increase fuel supply and, consequently, shaft torque to maintain constant rpm (and as power = rpm x torque, there you have that extra power). However, this can only be sustained for a limited amount of time before the temperature alarm cuts off the fuel.

    USCGC Glacier had a similar “limited-time maximum power” – it could maintain 22,000 shp for four hours at a time while the continuous rating was 16,900 shp. I would suspect this relates to the cooling of the electric propulsion motors. This is somewhat uncommon in the icebreaker world – typically only the maximum continuous rating is quoted, and the cooling system is dimensioned to meet the maximum rated power of the propulsion motors.

  4. Not sure who is proofreading the article, but this sentence:

    “With the propulsors, with one fixed and two steerable, we were able to optimize the seakeeping capability so when you’re going on long transits from Washington to Antarctica the crew is not beat to a pulp or heavily fatigued because of the stability characteristics in open water.”

    Two observations;
    A – The bow thruster will have limited effect on seakeeping at a cruise bell in any seas over 3 feet. B – Is there an implication of negative stability or neutral stability? if so, this is a design that probably shouldn’t be proposed.

    If Halter is going to publish specifics on an upcoming production, they should ensure the published details are well written. Just my .63 cents.

    • This is not about the bow thrusters, the propulsors referred to are the two steerable azipods and a non-steerable central prop shaft.

      I also do not see those as making the ship any more stable than it might have been otherwise.

      It does seem they wanted to say this ship will not roll as badly as Polar Star

      • It appears that it would be more comfortable than a Polar simply as a function of the hull design. There are retractable fin stabilizer systems but I can’t imagine they would use them in this ship. There also isn’t a mention that this ship would be able to break ice in an oblique configuration (as in use in the Baltic on some newer ships) or that it would be configures as Double Acting (such at the Double Acting Tankers that break their own ice by driving “backwards”.

      • Thank you, Chuck, I didn’t look closely at the picture and didn’t see the center prop.

        And your last sentence is also part of my view, if this proves out during sea trials, good. If not, we should ask for a refund. 😉

    • You’re not the only one puzzled about Halter’s description of the PSC’s technical features and how the vessel would be somehow “slicing the ice”. To me, the hull form looks fairly normal, albeit perhaps a bit more emphasis on improving seakeeping and reducing slamming with a smaller waterline opening angle. Otherwise, it’s the same old breaking by bending the ice downwards…

      When it comes to seakeeping, modern icebreakers tend to be somewhat better than their bathtub-shaped predecessors due to sharper bilge strakes, but it’s unlikely that a specific propulsion configuration would make the ship more stable in rough seas. While the PSC definitely won’t have bilge keels and likely there’s probably no retractable fin stabilizers either, there may be an anti-rolling tank within the ship. Those have been found to work just fine.

      • Rereading this it occurred to me that I have seen instances of the rudder being used as a stabilizer and perhaps the Azipods might be used in the same way to include a thrust component in opposition to the roll. Still have my doubts.

      • While that may be possible in theory, I’m not sure if it can be achieved in practice as the Azipods produce so much steering force.

  5. Pingback: Does Atlantic Fleet Need an Icebreaker Capability? | Chuck Hill's CG Blog

  6. Have you seen this video yet? I’d take the claim about a 17-megawatt thruster with a grain of salt, though, unless the ship is intentionally designed with excessive propulsion power redundancy.

    [video src="http://www.navalarchitects.us/images/HPIB%20video_05-09-2019_EM.mp4" /]

    • Thanks for the link. For those who may not recognize it the actual link is just the part between the quotation marks, copy and paste.

      [video src="http://www.navalarchitects.us/images/HPIB%20video_05-09-2019_EM.mp4" /]

      Re the propulsors. 17 MW (22797 HP) does seem unusually high considering there will be three (51 MW or over 68,000 HP) and the total generator capacity is reported to be 45,200 HP. This would only make sense if (1) the motors were made in discrete steps and the next smaller would not be large enough, or (2) the thinking was that if there was a casualty to one of the thrusters, full generator power could be diverted to the remaining two thrusters.

      • I guess WordPress attempts to embed the video but it doesn’t work for some reason. Oh well, the URL can be copy-pasted easily. The video is worth watching for everyone interesting in this project as it shows some model test footage for VT Halter’s design.

        As for the propulsion units, ABB’s Azipod range indeed comes with discrete steps, but within each propulsion motor frame size the power rating can be adjusted freely – for example, the largest unit (VI2300L) is available for power levels ranging from 13 to 17 megawatts. There are a number of valid engineering reasons for derating the propulsion motor instead of having “power redundancy”, but then again in a USCG cutter it could make sense to have the possibility of diverting full power plant output to 2/3 of the propulsion system in case of unit casualty. I guess we just have to wait until they release more details.

      • I have no idea why wordpress added text around the link, but it made it impossible to just click on the link. Still possible to copy and paste the part between the quotation marks, but I have never seen it do this before and it is an inconvenience.

    • Yes really the only news seems to be that the project is not being delayed by the COVID-19 outbreak.

      We know Polar Stern II is not under construction and was never even funded.

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