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Post by gordon on Nov 15, 2008 11:48:23 GMT -8
This is a rather interesting issue, I would assume that the prop and shaft position would have been spec'd by BCF & their engineers when the plans were drawn up, woul this problebe quite difficult & expensive to rectify now I wonder if this erosion issue has occurred at any of the other terminals that the Coastals use?
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Post by oceaneer77 on Nov 18, 2008 20:16:10 GMT -8
aaah finally a good argument on the site again.. it was getting quiet!
A long time ago we were going to compare the cost per car.. which is the only true way of seeing if they are efficient or not. But with all the reports i hear the new ferries are less efficient. As for waiting a year to see the fuel burn figures that it totally not needed. The engines will burn the same amount this year as next year as the year after, and they will do it on an about the same rate pre trip. (small adjustment for break in.. _005%).
but still after all of this.. i find it unbelievable that we can build a new ship with new and lighter materials, new and reportedly more efficient engines, new and improved hull design and still we come out behind!! This seems to the the standard of our shipbuilding industry. Same job, more bells and whistles, less efficient.
The cavitation issue of the propellers is a major issue and is with out a doubt one of the contributing factors to the fuel burn. only 2 fixes exist, 1) reduce the diameter of the propellers 2) ballast the ship to keep the props deeper.
I have often thought that the loading of the ships is wrong as all cars/trucks go strait to the bow and leave the stern light. Resulting in very poor trim and the prop being shallow... I wonder if turning the ship 180 would result in a fuel saving? Of if they could be loaded to trim properly.
oceaneer77
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Post by yvr on Nov 18, 2008 21:17:46 GMT -8
aaah finally a good argument on the site again.. it was getting quiet! oceaneer77 "So true Oceaneer." Over in the Coastal Renaisance in service thread, Flugelhorn posted a link to "theTyee.ca". That source has an excellent story and public comment on this issue. For whatever reason Flugelhorn's story disappeard at reply#432, but my quote captured his link. YVR
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Post by herrbrinkmann on Nov 18, 2008 22:23:14 GMT -8
I stayed quit for a long time but now there is too much misunderstanding also in this awful article published yesterday: Cavitation is a word everybody can write and speak but only very few really understand what cavitation is all about. It is very dangerous just to say cavitation when you see some air bubbles in the water.
I tried to explain some month or maybe a year ago, what different types of cavitation there is. When the Coastals are in the dock, the propellers suck air- yes, no doubt. But this is not cavitation. You get cavitation when you have a vacuum bubble on the propeller blade or on the tip of the propeller and the bubble collapsed and the following water hits the propeller. This can make noise or can be erosive to the material. On the Coastals there is no cavitation. And there is also a misunderstanding about the position of the propeller. When the ship is in the dock, it looks, as if the prop is too near to the surface. Yes- it looks like. You will also see, that there is a tunnel above the propeller. At this tunnel, the hull form comes above the waterline ,which at first sight makes no sense. But by doing so, you are able to increase the diameter of the propeller and so make it more efficient. During sailing the tunnel is sucked full of water and the propeller rotates happily in water and is not able to suck air or will cavitate.
Regarding fuel consumption: I do not have figures but I again ask, if the consumption of fuel for the operation of the vessel is counted for different types of vessels: The Coastals only have four ME for generating electricity used for propulsion and cooking the meals. How is it on the other BC ferries?
Trimming of the Coastals: There is the possibility to trim the vessel for/aft. According requests from BCF trim tanks have been arranged at the fore and aft end of the vessels. So if the vessel is only loaded at the fore end, the aft trim tank should be filled.
I would not say that everything is perfect but I am disappointed the there are articles where somebody thinks he has understand extremely complex technical things and now appears as the problem is analyzed and telling what FSG has done wrong.
I hope that not all of you trust blindly everything which is in the press. If anybody has more question, ask me, I will try to answer! ( I can understand, that your only source of information is the press - not always the best source)
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Nick
Voyager
Chief Engineer - Queen of Richmond
Posts: 2,078
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Post by Nick on Nov 18, 2008 22:45:31 GMT -8
Don't worry Markus, we all take what is written in the press about BC Ferries with many grains of salt. I have yet to see an article written in any of the major newspapers on the West Coast that doesn't have at least one major error. The only articles that even come close are Jack Knox's editorials in the Times Colonist, and he doesn't get very specific so it's a little easier to write.
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Post by Scott (Former Account) on Nov 18, 2008 22:58:10 GMT -8
Regarding fuel consumption: I do not have figures but I again ask, if the consumption of fuel for the operation of the vessel is counted for different types of vessels: The Coastals only have four ME for generating electricity used for propulsion and cooking the meals. How is it on the other BC ferries? EXACTLY, Markus! The Coastal's have four MaK 8M32C's solely for generating electricity. This powers the motor to drive the propellor, as well as all electricity needed for the operation ship. The C's use two MaK 12M551AK's as prime movers, as well as seperate Mitsubishi generators for generating electricity for the operation of the ship. I doubt that has been factored in to any of these so-called 'reports'........
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Post by Hardy on Nov 19, 2008 3:28:35 GMT -8
Interesting (as always) description Markus regarding the effect that is created by the props when moving slowly or in port; your explanation makes perfect sense now that I have heard it. As for comparing apples to apples and not to eggplants (ie: hotel load off of auxillaries), this is the same argument that I have been advancing in regards to the displacement figures that are posted by BCFS and registered in the database at TC (by BCFS).
Before you can draw comparison between two un-equally described/quantified objects, the playing field must be somewhat level...
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Post by Low Light Mike on Nov 19, 2008 6:10:40 GMT -8
aaah finally a good argument on the site again.. it was getting quiet! oceaneer77 "So true Oceaneer." Over in the Coastal Renaisance in service thread, Flugelhorn posted a link to "theTyee.ca". That source has an excellent story and public comment on this issue. For whatever reason Flugelhorn's story disappeard at reply#432, but my quote captured his link. YVR Another member posted the exact same Tyee link (10 minutes after I did) in the "Flensburger general yard thread" on the new ferries page. So to avoid duplication, I deleted my post that you referred to above. Good story, very interesting reading, and interesting readers' comments at the bottom of the story. Not that all this makes the story true in every way, but it is an interesting read for us interested stakeholders, with our usual grain-of-salt filter. re the possible misinformation being circulated in these stories: - maybe this is a good example of how a story can cascade when it keeps progressing without adequate response from the authority (ie. BCFS). - If BCFS were to respond specifically to the various allegations in stories such as in Thetyee.ca, would this put an end to the speculation? Or would it just feed more cascading of rumours? - Just wondering if BCFS is being smart in giving only corporate-speak short-responses to these reporters? www.thetyee.ca
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Post by herrbrinkmann on Nov 19, 2008 6:23:40 GMT -8
Good story, very interesting reading, and interesting readers' comments at the bottom of the story. www.thetyee.caThe most interesting thing for me is, that there are SO MANY experts in marine engineering knowing close to everything about shipbuilding and having solutions. Yes, we used thinner plates, as the prices were so high??? Hmm, there are certain rules which require a certain thickness. Deck 5 is closed because it is too dangerous weight-wise? OK- then please use one deck higher. We forgot to adjust the position of the propeller? Ah-sh*t, the whole time I thought we forgot something- now I know what it was. to be continued (sorry for that sarcasm)
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Post by EGfleet on Nov 19, 2008 9:47:46 GMT -8
Another article from the Tyee: German academic paper warned BC Ferries' needs were hard to meetBy Andrew MacLeod November 18, 2008 04:49 pm 2 comments B.C. Ferries set “very hard to fulfill” design requirements for the new Super C-class ferries, according to an academic paper whose authors include a Hamburg University of Technology engineering professor and an employee of the German shipyard that built the vessels. The paper also says that much of the Flensburger Schiffbau-Gesellschaft design was tested through numerical models, rather than actual physical models. The Tyee reported today that the new ships are having serious cavitation and fuel consumption problems. B.C. Ferries spent $542 million to have FSG build the Coastal Renaissance, Coastal Celebration and Coastal Inspiration. “Some of the Design requirements put forward by BCF had been very hard to fulfill in the final concept,” said the paper by professor Stefan Krüger, FSG employee Heike Billerbeck and Tobias Haack. “Most challenging was the demand for extremely low fuel consumption, low wake wash, and very good steering performance that had to be combined with the requirement for a diesel electric power plant.” B.C. Ferries also needed the ships to accelerate quickly from zero to the “quite high” speed of 21 knots, it said. To meet the requirements, FSG came up with “an unconventional propulsion concept” for the propellers and “a completely new hull form.” Alternative designs were tested numerically, it said, in part because the designers were in a hurry. “It was found that the majority of the design tasks could only be handled with numerical simulations, where the simulation models had to be generated on time during the hot product development phase.” The models helped FSG develop a “competitive product” that B.C. Ferries chose through its selection process, the paper said. A commenter on The Tyee story found a PDF of the academic paper. The PDF is no longer available, though a cached copy can still be found. FSG's head of design, Broder Hinrichsen, said in an interview the three new ferries met all of the specifications set by B.C. Ferries, including for fuel consumption. B.C. Ferries spokesperson Deborah Marshall did not respond to the Tyee's requests for comment today. Andrew MacLeod is The Tyee’s Legislative Bureau Chief in Victoria. Reach him here. www.thetyee.ca/Blogs/TheHook/Transportation/2008/11/18/FerrySpecs/
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Post by boardsailor on Nov 19, 2008 15:20:14 GMT -8
OK, I used therm "cavitation" in broad meaning not going scientific here. Mr Brinkmann, you are absolutely right if comes to describing cavitation on prop surface. But this is not naval architecture exam so if I may, I use that therm in broader meaning. I still am of the opinion that the good thing could be improved. Like at the start up instead rapid ramping up of speed on propulsion motor which overloads generators, use Variable Frequency Drives. That would facilitate adjusting speed incrementally. And as a side benefit would allow to reduce rpm while in dock on shore end of the ship. That in turn would reduce famous by now vibrations. I do understand that your design is a compromise to meet BC Ferries specifications. Ship is performing well at the speed when aft end squats due to thrust of the driving prop. The enjoyable ride ends when on approach to dock mode 2 is engaged. With single speed forward prop working in astern direction is shaking whole ship in spectacular fashion. While docked, mode 2 is still engaged to the detriment of the traveling public. According to Ferries advertisements, new vessels suppose to be fast, quite, fuel efficient and vibration free due to mounting engines on insulated from the hull platforms. What we got is somewhat different from expectations. On top of that design of the extended loading platform at the bow end will be problematic at high wind conditions to maintain speed(slapping against waves). By the way fuel consumption is on ships calculated on daily basis using dips in fuel tanks. It is provision to monitor fuel consumption of main engines, specially on ship like Super C with 2000 parameters monitored continuously. But if comes to fuel consumption is one figure recorded on daily basis.
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Post by Northern Exploration on Nov 19, 2008 19:26:50 GMT -8
Good story, very interesting reading, and interesting readers' comments at the bottom of the story. www.thetyee.caThe most interesting thing for me is, that there are SO MANY experts in marine engineering knowing close to everything about shipbuilding and having solutions. Yes, we used thinner plates, as the prices were so high??? Hmm, there are certain rules which require a certain thickness. Deck 5 is closed because it is too dangerous weight-wise? OK- then please use one deck higher. We forgot to adjust the position of the propeller? Ah-sh*t, the whole time I thought we forgot something- now I know what it was. to be continued (sorry for that sarcasm) No need to apologize for the sarcasm Markus. It was deserved and gave me a laugh. Thanks. Feel free to employ sarcasm as required again in the future.
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Post by Ferryman on Nov 19, 2008 19:29:58 GMT -8
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Post by Northern Exploration on Nov 19, 2008 19:59:34 GMT -8
Thanks Chris. I had forgotten all about the Spirit broohaha. It was short lived. I sailed 6 months or so after she went back in service and loved it.
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Neil
Voyager
Posts: 7,151
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Post by Neil on Nov 19, 2008 20:08:14 GMT -8
Chris, I don't think that's a 'reality check'. It's just the most right wing newspaper in Canada (which is about two steps away from death's door, by the way) engaging in some anti-left, anti-union rhetoric.
This is a pretty intriguing story, and not being an engineer, I'm just following with interest the input from Flensburger, and the countering arguments from some engineering types here. Maybe the truth is somewhere in the middle. In any case, the National Post really has nothing worthwhile to contribute.
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Post by Canucks on Nov 19, 2008 21:37:23 GMT -8
I would have to agree with Neil about this article. The tyee is on one end of the pole and this article is on the other. To really find out we would need an independent source to conduct test that take all the variables into consideration, which is unlikely to happen. For now we are stuck with the media's usual taking a piece of information and running with it.
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Post by Hardy on Nov 20, 2008 0:11:04 GMT -8
No no no no no -- please DO NOT apologize -- and keep up the sarcasm ... it is RIGHT up MY alley, and I had a hard time typing this as I was chuckling so hard my keyboard ran away .... lol Sometimes it is just best to turn OFF the "politically correct" filter and say EXACTLY what you are feeling at the moment! Good on you Markus!!
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Post by gordon on Nov 20, 2008 8:12:00 GMT -8
Boardsailer mentioned the issue of significat vibrations while approaching the terminal and in dock(using mode2)
Will this be a problem transiting Active Pass in Mode 2?
How difficult wuld a problem like this be to rectify?
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Nick
Voyager
Chief Engineer - Queen of Richmond
Posts: 2,078
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Post by Nick on Nov 20, 2008 8:53:03 GMT -8
The Coastals do not have to use mode 2 to transit Active Pass. That requirement is only for the current C-class, and came about after the Queen of Alberni incident in 1979. The Coastals were designed specifically to transit active pass in normal operating conditions. On her delivery voyage, the Celebration went through the pass at 21 knots, according to her captain.
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Post by Northern Exploration on Nov 20, 2008 9:14:55 GMT -8
Aircraft, the advanced examples of engineering and technology they are, have issues when they are new off the line. No amount of flying in the test phases and FAA certification gets all the bugs out. I can give numerous examples of this. This is normal, to be expected, and yes aviation boards are full of people having a cow (maybe a bird of somesort would be a better analogy?). The internet gives us a detailed look at so many things we never heard about or frankly cared about before, because it usually was so far after the fact when it was reported. I have never looked but I am sure there are websites to discuss belly button lint and I am sure someone can cook up some controversy there . The Spirits got a lot of coverage by the media but the hyper microscopic gaze of the internet didn't come to play in almost real time. Time will tell if the Coastals settle into the same reliable years of service. I suspect this controversy will go away because it will all be solved and a new one will take its place. By then it should be the NorDisco whoever, or whatever she will be, taking the heat. As an asside, I laughed out loud at Starbucks when I read the Tyee call the Save Our Ferries site as a consumer watchdog site. Consumer watchdog brings to mind Ralph Nader, Consumer Reports or "Protegez-Vous" in Quebec. Not a Union/Employee lobby and information site.
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Post by DENelson83 on Nov 20, 2008 11:23:53 GMT -8
Consumer watchdog brings to mind Ralph Nader, Consumer Reports or "Protegez-Vous" in Quebec. And there's also The Consumerist.
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Neil
Voyager
Posts: 7,151
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Post by Neil on Nov 20, 2008 12:28:45 GMT -8
The internet gives us a detailed look at so many things we never heard about or frankly cared about before, because it usually was so far after the fact when it was reported. I have never looked but I am sure there are websites to discuss belly button lint and I am sure someone can cook up some controversy there . NE, you must be the only person on here who's never looked up belly button lint. Aren't you Torontonians curious about anything? I found a forum, or at least a thread, discussing BBL, but I won't post the link, because there were some naughty words. Sorry for the extreme thread diversion. Back to the propeller argument.... although I fail to see how we can solve anything without good ol' Cascade weighing in. *Sigh*... the good old days....
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Post by Hardy on Nov 20, 2008 21:43:36 GMT -8
As far as Mode-2 vibrations in-dock and arriving/departing, I was onboard the CR out of Duke last night and the Cafeteria end was stern. I was having dinner as it was 2015. The vibration when docked is noticeable, but not too bad. HOWEVER, once she is away, my food was running away from me on the table!! Harsh vibrations, and a real froth of churning water being forced hard at the pilings and dock structure at Duke; very very noticeable in the dark from the Cafeteria with the bright lights shining out of the stern.
I can see how foreshore erosion has become a concern with the churn that the Coastal props send out.
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Post by gordon on Nov 21, 2008 7:26:41 GMT -8
How long after departre does the significant vibration stop?
If the props have to be run at that speed while in dock, what steps can BCF take so as this shore erosion probelm doesn't become a major one?
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Post by kerryssi on Nov 22, 2008 14:46:03 GMT -8
Economy....it seems to me that the only measurement that makes sense is....how many passengers/vehicles are moved and at what total cost/profit. For answers you have to wait until after the break in period and after the summer/winter loads are totaled. Give it a year and you will know. It even costs to tie them up.
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