Talk:MV Viking Sky

Capacity

Capacity says 930 passengers, while number of passengers to evacuate is 1300? — Preceding unsigned comment added by 2001:4662:4FF8:0:FDB3:2423:4D67:EAB8 (talk • contribs)

2001:4662:4FF8:0:FDB3:2423:4D67:EAB8 That figure includes 400 crew. Mjroots (talk) 20:51, 23 March 2019 (UTC)

The mentions of injures from the incident make no sense in the current form of the article

The article says that the ship had an engine failure, and then all of a sudden dozens of people got to be injured. It has to be clearly stated how and why they got their injuries. Otherwise it all is just poorly edited/written. 93.185.30.66 (talk) 07:16, 24 March 2019 (UTC)

How many engines?

The article is unclear if the ship has 2 or 4 engines. I think its four generators driving two engines. Can someone who knows about these things resolve? Lyndaship (talk) 16:50, 25 March 2019 (UTC)

Four engines per Fakta om Fartyg & other sources. Mjroots (talk) 18:22, 25 March 2019 (UTC)

It's unclear if the diesel engines are physically attached to the propshafts (mechanical drive), or if the connection is purely electrical. Some ships have the diesel crankshaft go straight through to the propellers, with electric motors attached working as either generator or motor, depending on bridge commands. Other ships have no mechanical connection, instead a generator converts diesel engine torque to electricity, and through electric power conversion and cables to power electric motors for the propellers.

As for the Hagland Captain mishap, here is an overview with some details. Translation indicates that the electrical switchboard was flooded by a rogue wave. TGCP (talk) 13:09, 26 March 2019 (UTC)

I think the article pretty clearly states that the ship has four main generating sets that produce power for two electric propulsion motors driving the propellers. How should it be further clarified? Tupsumato (talk) 19:07, 26 March 2019 (UTC)

She has four MAN 32/44CR series main diesel generators: two 9-cylinder engines rated at 5,040 kW (6,760 hp) and two 12-cylinder engines producing 6,720 kW (9,010 hp) each. This power plant produces electricity for all shipboard consumers, including two 7,250-kilowatt (9,720 hp) electric propulsion motors - Four generators; 2 plus 2 engines, 2 propulsion motors confuses me, it says 4 engines but 2 motors provide the propulsion. Furthermore the cite provided does not mention generators (calling them engines) and makes no mention of the number of propulsion motors. A better source is needed and one which supports the asserted facts attributed to it Lyndaship (talk) 19:22, 26 March 2019 (UTC)

Main source for engine description is "Ship-technology.com", which seems to have credibility issues. I just searched the web filtering for before March2019, but found few useable sources. The Incident Report will likely show the precise configuration. TGCP (talk) 00:09, 27 March 2019 (UTC)

We can change the citation to IHS Sea-web which also explicitly states that the 12-cylinder engine is in vee configuration (if it was not already apparent from the engine type, 12V32/44CR). Tupsumato (talk) 06:34, 27 March 2019 (UTC)

Did some light c/e to clarify this paragraph and added the Sea-web reference. The database entry for machinery overview reads "4 diesel electric oil engines driving 2 generators each 5,040kW 6,600V a.c. 2 generators each 6,720kW 6,600V a.c. connected to 2 electric motors of (7,250kW) driving 2 FP propellers at 148 rpm" and the 9L32/44CR and 12V32/44CR engines are identified separately in another entry with some additional detail. Tupsumato (talk) 06:48, 27 March 2019 (UTC)

Open sources are generally preferred over closed sources like Sea-web, but at least it's better than dubious ones. I suggest that the engine brochure is also kept, as it likely shows info not available in Sea-web. It's not yet clear from the article that it was the diesel engines that cut out, not the electrical power, so the conversion technology may be of interest. TGCP (talk) 06:53, 27 March 2019 (UTC)

I generally use IHS Sea-web only when I cannot find an equally reliable open source for certain technical details. However, as per WP:RSC that's perfectly fine and difficulty of access (in this case, paid subscription) is not a reason to disregard the source. As for the MAN brochure, it provides no information whatsoever for this particular ship and thus I don't think it should be in the article (just like a link to general brochure of Rolls-Royce Promas system shouldn't be). If additional sources are needed, we could also refer to Significant Ships 2015 which has an article about Viking Sky's identical sister ship, Viking Star, and provides much of the same information. Description of the general layout of the power plant and propulsion system (in this case, four gensets and two electric-driven shaft lines) is of general interest in all ship articles regardless of whether there has been an incident or not; however, whether it was the engines that cut out or a problem in the electrical system is something that is yet to be revealed by the investigation, so we should be very careful not to speculate in Wikipedia. Tupsumato (talk) 09:40, 27 March 2019 (UTC)

I just realized the same info is available in the Fincantieri datasheet so the Sea-web citation can be dropped here. Tupsumato (talk) 09:43, 27 March 2019 (UTC)

The Fincantieri sheet is very short, and only infers the type of operation - it's unspecific. I don't think it is sufficient. I'll show the MAN brochure here for easy future reference. NMA quickly found a probably cause, but waits for confirmation. TGCP (talk) 10:33, 27 March 2019 (UTC)

The Fincantieri brochure explicitly defines what kind of main engines are installed on Viking Sky and what are their power ratings. With the exception of identifying 9L32/44CR as a 9-cylinder inline engine and 12V32/44CR as a V12 engine (which is already indicated in the engine type), what additional information in the Viking Sky article needs to be cited from the brochure? Tupsumato (talk) 10:48, 27 March 2019 (UTC)

It's great that you found the sources we couldn't. You have seen the Sea-web page, but most readers haven't. Without that reference in the engine section, the stated info is not fully covered by the attached sources. We infer that Sky's engineering is identical to its sisters, but sources don't state that. Without clarification, the above stated alternatives (direct diesel drive with e-motor attached; Parallel-hybrid) are also possible. The Series-hybrid layout may be apparent to ship enthusiasts, but an encyclopedic article should cater to uninformed people as well. I tried to find well-informed free sources, but unfortunately we are left with sources that are either dubious, lacking or closed. .. The diesel engines are probably "father&son" combined to drive two generators (not a generator for each engine) in each room. That info is likely to be relevant, but we will see shortly. When the ship went dead in the water, the backup-generator (Vadset ref) is notable because it was likely the only thing keeping the ship alive, making communication and restart possible. TGCP (talk) 14:42, 27 March 2019 (UTC)

Now the power plant description was just plain absurd. I fixed it as much I could over phone; will continue tomorrow and look for sources. Why compare the ship to a platform supply vessel without explaining why they have more redundancy than Viking Sky? Also, all ships have an EDG; we can definitely mention it but don't give it some elaborate new name when it's "just" an EDG. Tupsumato (talk) 16:34, 27 March 2019 (UTC)

Why the harsh tone? The refs support the first edit, and if better text is needed, just add it. If by "EDG" (not found in source) you mean Emergency diesel generator, it redirects to Emergency power system. A father&son is shown here as a mechanical coupling. Cruise ships are required to have a high level of redundancy (as referred to in SRtP) but not as high as for supply vessels (shown in ref) - we could add why (economy), but that's complicated and not a focus for this article (until rules change as a result of this). Source says engine rooms are fire-tight and water-tight - "sealed" is perhaps too strong a word, as outside air is blown through to the engine intake (which allowed seawater to short circuit the Hagland). TGCP (talk) 17:16, 27 March 2019 (UTC)

I will look into this tomorrow for both factual content as well as terminology; for the time being, you may revert to previous edit if you like. However, in your link, the layout example is for diesel-mechanical drivetrain; Viking Sky is fully diesel-electric and "father and son" refers simply to having both 9- and 12-cylinder engines instead of just four identical 12-cylinder units. I think comparison to PSVs is irrelevant; why not compare cruise ships to dynamically-positioned deep water drillships which have even more redundancy? Or naval ships? They are all different kinds of ships for a different mission and the reasons for their higher level of redundancy are also totally different. As for being sealed, the engine rooms are separated from each other by watertight bulkheads and they are in different main fire zones; sealed would indicate an inaccessible box whereas in reality there's probably a watertight door between them. Thus "separate(d)" is better word. That's also probably the word you'll find in the rules. Tupsumato (talk) 18:44, 27 March 2019 (UTC)

Sources say Sky uses father&son, but the cable-only diesel-electric is vaguely sourced. ShipPipedia shows both configurations, but not together. Page 165 says the MV Oriana (1995) has diesel-electric father&son engines with a 4.2 MW electric motor/generator on each shaft.

Level of redundancy is a critical point for the sources, so it should also be an essential point in this article. This source's experts view the failure as a level of redundancy lower than required. This source compares it to offshore vessels of which PSV was the closest I could find.

"Separate" is not a strong enough word to describe the containment of water and fire, but "sealed" is probably too strong. A better word was needed. TGCP (talk) 20:19, 27 March 2019 (UTC)

Oriana is not a diesel-electric ship; the 6- and 9-cylinder MAN diesel engines are driving controllable-pitch propellers via double-input-single-output gearboxes in a father-and-son configuration (as indicated in the source you provided). You're confusing shaft generators with propulsion motors; those are typically used to produce electricity for e.g. electrically-driven transverse bow and stern thrusters without disturbing the ship's main electrical network, but can also be used instead of auxiliary diesel generators (Oriana has four of these) to provide electricity for hotel functions during transit. Recently, particularly in ice class applications, shaft generators have been used both as an alternator to produce electricity (power take-off; PTO) and a propulsion motor (power take-in; PTI) to provide power and torque boost when the vessel is operating in ice-covered waters, but that's a topic outside of this discussion.

Regarding redundancy, I agree that it's an important topic and should be covered either in the general characteristics or in the incident chapter as it's not an unique feature for this particular ship (we shouldn't put too much emphasis in the wrong chapter to give an impression that Viking Sky is somehow special in this respect than other modern cruise ships). However, I'd steer clear from making comparisons to vessel types that a casual reader may be even less familiar with than cruise ships; we would have to start off by explaining what exactly is a platform supply ship and why it has more redundancy than a cruise ship. Whereas cruise ship's redundancy ensures "safe return to port", a PSV needs redundancy so that dynamic positioning capability is retained even if any single propulsion unit (DP level 2) or any single compartment (DP level 3) is lost. As for your source, it's natural that a Norwegian source would compare the cruise ship to an offshore vessel as many Norwegians are familiar with that particular type of ship.

I agree that "separate" alone is not sufficient; we need to further specify that the separation is sufficient to withstand flooding of or fire in the adjacent engine room as per SRtP requirements.

I will open a separate heading for the reference issue. Tupsumato (talk) 05:50, 28 March 2019 (UTC)

Source says Oriana's propeller (each) is driven by (among others) a 4.2 MW electric motor fed by diesel gensets. It may be a special case (the e-motor is smaller than the propshaft diesels), but it is an example that categories have overlap; they are not sharply divided.

The redundancy discussion involves whether the SRtP is sufficient for cruise ships. Either that, or SRtP may not have been fulfilled in practice (port was not reached unaided). In any case, it's a notable point. TGCP (talk) 13:09, 28 March 2019 (UTC)

I stand corrected. The source states that "each father-and-son pair drives a highly skewed Lips CP propeller via a Renk Tacke low-noise gearbox which also serves a 4200kW shaft alternators operating as propulsion motors", meaning that it has exactly the kind of PTI/PTO system I described above for ice class applications. The propulsion system could be described as "combined diesel-electric and diesel", meaning that the propellers are driven in part mechanically by diesel engines, in part electrically by the shaft generator/motor. Interesting (and worth including in the Oriana article)!

I revised the SRtP part of the article to further describe what is it about; could you kindly check it. We can include why it failed in the incident section. I retain my opinion that a comparison to PSVs is not relevant; we are taking about passenger ships here and the only relevant comparison would be to pre-SRtP cruise ships. Tupsumato (talk) 13:46, 28 March 2019 (UTC)

Rudder and propeller is Rolls-Royce Promas. It seems to be unrelated to the engine troubles. TGCP (talk) 00:27, 27 March 2019 (UTC)

Yeah, Promas is just a proprietary propeller-rudder configuration and is not relevant to this indicent. However, it may be incorporated to the general description of the propulsion system. Tupsumato (talk) 09:40, 27 March 2019 (UTC)

Minor point - the 14:29-edits are more detailed about each section, but have also made the power flow (from diesel to propeller wake) less easy to follow, which is what I believe is part of what Lyndaship was requesting. TGCP (talk) 14:10, 28 March 2019 (UTC)

I can try to revise the text again tomorrow morning. We have so much text on the technical side that splitting power plant and propulsion to separate paragraphs makes sense, as well as adding something that puts things into perspective (those electrical sockets in the cabin). Perhaps the propulsion paragraph could remind that the electricity from the drives comes from the main switchboard. I also now agree that the order should follow "flow" of energy; will revise once I'm back at desktop. Let's just avoid getting too technical and make the information useful also to casual readers. Tupsumato (talk) 15:46, 28 March 2019 (UTC)

Y Done; please review. Tupsumato (talk) 05:36, 29 March 2019 (UTC)

I was confused by mentions of generators, engines and motors. I now understand that the engines act as the generators to produce the electric power some of which the motors consume to propel the ship. I really appreciate the way you guys have gone about clarifying the article and providing sources for it all. So often some wrong "fact" gets into an article and by the time its challenged its been copied by some lazy journalist into his RS publication and that is then used as a source to prove the wrong fact on wiki. As to the question about open and closed sources I prefer open but if the info is only available in a closed that's better than no information or if the open is wrong information then I prefer to see the closed used. Lyndaship (talk) 18:51, 28 March 2019 (UTC)

Oil pressure system

Secondary cause is loss of oil pressure, resulting in alarms that shut down all diesel engines to protect them from damage. Root cause is unknown, as oil level was within specification. Engine manual: Lubrication system begins on page 153. Notable sections are
p154 "The engine frame tank has the function of the lube oil service tank. The mainpurpose is to separate air and particles from the lube oil, before being pum-ped back to the engine. Even a low oil level should still permit the lube oil tobe drawn in free of air if the ship is pitching"
p155 (prelube, postlube) "The volt-age for automatic control must be supplied from the emergency switchboardin order to secure post- and prelubrication in case of a critical situation. In case of unintended engine stop (e.g. blackout) the postlubrication must bestarted as soon as possible (latest within 20 min) after the engine has stop-ped and must persist for minimum 15 min."
p161-164 diagrams. .. TGCP (talk) 17:38, 27 March 2019 (UTC)

There is some speculation about the root cause in the press release and I believe it can be included in the article as a probable cause. While the terminology has been used in the above link, I would prefer not using the words "engine failure" repeatedly as they give an impression that the engines suffered some mechanical damage (they apparently shut off as a precaution against damage due to low oil pressure). However, we should have good sources on the topic by tomorrow; the one linked is probably the best for the time being. Tupsumato (talk) 19:23, 27 March 2019 (UTC)

Sdir added. Engine guide page 286 says 5° pitch is max for continued lubrication. 2.4.7 says max 22° roll. TGCP (talk) 20:31, 27 March 2019 (UTC)

Those are SOLAS minimum requirements (Chapter II-1 Part C Regulation 26.1) unless deviation is permitted by administration. Tupsumato (talk) 07:55, 28 March 2019 (UTC)

Regarding importance of no-lube shutdown, SOLAS CHAPTER II-1 PART C Machinery installations, Reg. 27.5, Page 87 says "propulsion machinery .. shall be provided with automatic shutoff arrangements in the case of failures such as lubricating oil supply failure which could lead rapidly to complete breakdown, serious damage or explosion. The Administration may permit provisions for overriding automatic shutoff devices." Perhaps enhanced with explaining that a permanent loss of engine likely means loss of ship. TGCP (talk) 12:10, 29 March 2019 (UTC)

Other engine problems occur for ships. In 2016, at least 18 cruise ships suffered engine problems, some requiring tow to port ("Cruiselawnews" is probably not reliable, but they link to reliable sources). TGCP (talk) 15:01, 30 March 2019 (UTC)

Closed sources and lead ship issues

In the discussion regarding the power plant, the following issues were brought up:

• the use of closed sources such as IHS Sea-web database which require paid subscription (see also WP:RSC); and
• the use of sources about the lead ship of the class (Viking Star) to describe the technical details of the third vessel of the class.

The IHS Sea-web database entry supports not only the technical details I have included in the article, but also the fact that Viking Sky is a sister ship to Viking Star and its main features are identical to those of the lead ship, meaning that when it comes to facts and figures, we could also cite e.g. Significant Ships 2016. The sister ship-ism is also confirmed in e.g. this Rolls-Royce article.

While we can reasonably expect some good "open" sources to appear in the future as last weekend's incident is discussed in the media and the final incident report is eventually released, for the time being there is a danger that in particular technical information in the news articles can be incorrect or unclear. For example, certain details regarding the basic layout of the power plant may be omitted, leading to a situation where User:TGCP is proposing some rather unlikely plant configuration alternatives. Furthermore, I have already seen some rather ridiculous articles about the ship — how to avoid having those ending up as cited sources. As many people will come to Wikipedia to look for information about the incident in the coming weeks, we should avoid a situation where they will get misleading or incorrect information.

Anyway, I'm open for discussion and apologize my harsh tone in yesterday's discussion (above). I have also invited other editors from WP:SHIPS to participate in the discussion. Tupsumato (talk) 06:29, 28 March 2019 (UTC)

While a good open reference has now been included in the article to clarify many issues, I'd still like to see some kind of discussion on this issue. Tupsumato (talk) 13:30, 28 March 2019 (UTC)

I also want the article to reflect reality, but the best sources are outside common reach - thank you for sticking to them. We try to find a reasonably verifiable compromise between reliability and access. The way to avoid wrong sources is to compare them with reliable sources, so we can find the 'truth'. Comparison requires open access, preferably to more than the few editors with access to closed sources. I was content (although not satisfied) with closed sources.

I have seen several instances of comments describing Sky as having Azipods, which is unlikely, given the RR Promas and Star's Thordon seawater bearings. The Waertsilae and RR sources are from early Star days, before Sea and Sky were completed, but a significant change is unlikely. Small changes were made, mostly to passenger facilities. Star is still described merely as a "hybrid". TGCP (talk) 13:54, 28 March 2019 (UTC)

As a side note, "hybrid" is one of those buzzwords you can slap on pretty much anything... Tupsumato (talk) 15:37, 28 March 2019 (UTC)

There is absolutely nothing wrong with subscription-services, as long as they can be verified by someone with the subscription. Sources do not have to be free - after all there is nothing unusual about using books and magazines which the editor has to buy as sources.Nigel Ish (talk) 19:02, 28 March 2019 (UTC)

Nothing wrong with subscription services. As long as there is editorial oversight and it meets RS requirements, then by all means its acceptable. Llammakey (talk) 11:47, 29 March 2019 (UTC)

Per above, but with the proviso that if a fact referenced to a subscription only reliable source can also be verified by an open access reliable source, then that reference should be changed. There is a descending pecking order - open access, free subscription, paid subscription. Mjroots (talk) 13:28, 29 March 2019 (UTC)

That depends on the sources being equal quality - we should prefer best quality sources, whether subscription or free - also we may want to think about whether sources are likely to be persistent - we want to use sources that can still be found and verified in the future.Nigel Ish (talk) 13:31, 29 March 2019 (UTC)

If "free subscription" is the same as "registration required", then they are usually effectively open access - Equasis, for example, or some Class Societies' ship data (eg RINA). But we should probably differentiate in the pecking order between subscription sites that only exist in that form (eg SeaWeb) and those that we may use for convenience, for example the British Library's historical newspaper collection, or current online versions of newspapers like the The Times. Printed copies of this latter type can be read in some libraries, usually without payment. Some pay-sites, like "Miramar" are a hybrid (sorry, Tupsomato!) - most of the information is from open sources, though they are not identified in relation to specific data. Davidships (talk) 10:08, 1 April 2019 (UTC)