ren0312
-
Posts
116 -
Joined
Content Type
Forums
Store
Blogs
Downloads
Events
Gallery
Posts posted by ren0312
-
-
1 hour ago, chengkp75 said:
Uh, the France was a steamship, hence the "SS". Steamships are even less efficient than diesels or diesel electric, which is why they have been relegated to service where fuel efficiency doesn't matter, like nuclear power, and LNG tankers that burn the boil off cargo. The acceleration of a ship has absolutely nothing to do with which type of power plant is has, but is determined by a couple of factors; the mass of the ship that needs to accelerate, the waterplane area of the hull, the block coefficient of the hull, the power available to drive the ship, the torque limitations on the shafting and propeller, the diameter of the propeller, and the pitch of the propeller.
As noted above, the USCG had some CODOG power plants (note the second "O" in the acronym) which had diesel engines and gas turbines geared to the same propeller. They were not only difficult to maintain, but it was found that the fuel requirement of the gas turbine was such that it was rarely used, and therefore the capital investment was not justified.
As discussed above, the QM2 has CODAG power plant, where both the diesel engines and gas turbines generate electricity which then drives electric motors in the podded propulsion units (they are not ABB, so not azipods). Diesel electric propulsion has been found to be the most efficient power source for cruise ships, given their large hotel load requirements. Multiple generators (several diesel generators, or diesel generators with gas turbines) allow for close tailoring of the generating capacity to power demand, in order to keep the prime movers (diesels or GT) in their most efficient operating range.
As noted, gas turbines have better emissions than diesels, but they are less fuel efficient than diesels, especially at lower loads, so they are better suited for applications where they can be utilized exclusively at maximum load. While many of the cruise ships that have gas turbines installed, and they go beyond Princess and Cunard to RCI, Celebrity, and HAL, were supposed to use the gas turbines while in port in Alaska to reduce emissions, it was found that using them at the low load required by the hotel load on the large turbines installed was not fuel efficient, and those ships that strictly had gas turbines were refitted with diesels to take hotel load when in port. The gas turbines do provide the benefit of being able to "throttle back" in Alaska (i.e. less propulsion power needed, so lower generating capacity needed) with no change in emissions (diesels have more emissions at lower loads) which is a benefit in environmentally sensitive areas like Alaska.
I would say that the QM2 style plant is about the most efficient for a ship that has a requirement for that amount of power (117Mw). The gas turbines are only needed for the last few knots, so they are always used at full load, and their low weight and small size justifies their inclusion for "occasional" power usage.
As for building a new ship to replace the QM2, first off, regardless of what the price of oil is, the cruise lines realize there is a very limited demand for a ship that could do in excess of 24 knots, with it's attendant capital cost in power and propulsion equipment, and in operating cost for fuel. Secondly, the QM2 engines meet the lowest of the IMO's emissions requirements (tier 1) since she was built before 2011, and any ship that would be built to replace her would need to meet the current tier 3 requirements, with the attendant cost of these improvements in emissions control.
So why are a lot of US Navy ships like the Arleigh Burke, OHP, and Ticonderoga classes COGAG? They do not do 30 knots all day and more often cruise at a slower 15 knots or so, from what I know.
-
What are the advantages and disadvantages of each setup, say if you want to build a 35 knot ocean liner that can cruise at 30 knots all day long, like the QE2 or SS France? Diesel engines are bigger than gas turbines but use less fuel, and take forever to accelerate to 30 knots, gas turbines are smaller but use a lot more fuel. Did the QE2 cost less to run at 30 knots cruising speed using her diesels compared to the QM2 at 26 knots cruising speed? Because if the price of crude oil stays near 30 dollars a barrel for the long term, that might open up some possibilities towards say, Cunard, building a new ocean liner again, since the QM2 is nearing 20 years old.
-
2 hours ago, chengkp75 said:
Overseas Shipholding Group paid $37 million back in 2006. Largest ever at that time.
OOCL?
-
11 hours ago, rkacruiser said:
The definitions for all of the cruise lines' advertising is going to be needed to be revised when we get on the other side of this virus.
Free coronavirus vaccination packages? Free PPE packages?
-
Why is there no mid-market intermediate cruise line that I am aware of? Basically a cruise line that slots between Carnival/Royal Carribean/Norweigian and Crystal/Regent Seven Seas/Seabourne? Basically a cruise line that will deliver a higher standard of service and food compared to the mass market cruise lines, while being below the luxury cruise lines. Basically a Buick or Acura or the cruise industry, in that Buick or Acura are near luxury brands that slot between Cadillac and Chevrolet. Is there a market for a mid-market cruise line, with prices between say, Crystal/Regent Seven Seas and Carnival? Basically there seems to be a large gap in terms of the market between Regent and Norweigian that you can slot another brand. Maybe you can say that Holland America and Cunard used to fill this gap but it seems that they have also really moved downmarket.
-
Will some countries or places like Taiwan, HK, Korea, and NZ that pursued stamp out the virus strategies instead if herd immunity, or have simply acted very early and effectively to contain and eradicate the virus from their population, and appear have managed to almost eliminate coronavirus from their countries, enact travel bans against people from countries like Sweden that have pursued herd immunity strategies with respect to coronavirus, that is the strategy of deliberately exposing their population to the virus in the hopes that their population will gain herd immunity? Or even if a vaccine is made, suppose it is not completely effective, will we see places like NZ and Australia basically ban people from countries where coronavirus has already been very widespread among the population like the US, UK, and Canada for the foreseeable future, even for those who have already been been vaccinated, such as cruise ship passengers, due to doubts about the vaccines effectiveness? Also there is the possibility that coronavirus seems to be like herpes, that once you get it, you can never really flush it totally out of your body, and some virus will always remain in your body waiting to be reactivated and infect people again, so you will always be like a ticking time bomb waiting to reinfect unaware people.
-
From my inexpert point of view, it seems like the Titanic could have taken the same sort of damage as Costa Concordia without sinking or worse, capsizing?
-
Or to simplify the question, let us just say if Carnival Liberty, which is a reasonably new cruise ship, sustained the same amount of damage as the Titanic in the same way, would she be able to stay afloat for at least 24 to 48 hours, unlike Titanic which sunk in only a few hours? Basically would a reasonably modern cruise ship, like the Costa Atlantica, be able to take the same amount of damage that the Titanic did in 1912 and not sink until all of the passengers are rescued, unlike Titanic?
http://www.titanicology.com/Modifications_To_Olympic.html
-
Technical question, do cruise ships have better watertight bulkheads compared to the Titanic's days? I would define this as, basically, the Titanic was designed to have four watertight bulkheads fill up at the front, and not sink, and have 2 watertight bulkheads fill up at the middle, and not sink. Now after what happened to Titanic, the Olympic was modified, in that the top of the watertight compartments were made higher, so that now 6 bulkheads at the front could fill up (and the Olympic had seventeen watertight bulkheads after these modifications), and the ship would still not sink, now the question is whether a modern cruise ship like the Liberty of the Seas or MSC Meraviglia has as good or better protection than the Olympic post-Titanic modifications? So that the front third of MSC Meraviglia's watertight bulkheads could fill up, and the ship would still float, assuming that the bulkheads hold for at least 24 to 48 hours? Or 2 bulkheads in the middle of MSC Meraviglia could be holed and she still would float, which was what the Titanic was originally designed for.
https://en.wikipedia.org/wiki/RMS_Olympic#Post-Titanic_refit
Post-Titanic refit[edit]
Olympic as she appeared after her refit following the Titanic disaster, with an increased complement of lifeboatsOn 9 October 1912, White Star withdrew Olympic from service and returned her to her builders at Belfast to have modifications added to incorporate lessons learned from the Titanic disaster six months prior, and improve safety.[77] The number of lifeboats carried by Olympic was increased from twenty to sixty-eight, and extra davits were installed along the boat deck to accommodate them. An inner watertight skin was also constructed in the boiler and engine rooms, to create a double hull.[78] Five of the watertight bulkheads were extended up to B-Deck, extending to the entire height of the hull. This corrected a flaw in the original design, in which the bulkheads only rose up as far as E or D-Deck, a short distance above the waterline.[79] This flaw had been exposed during Titanic's sinking, where water spilled over the top of the bulkheads as the ship sank and flooded subsequent compartments. In addition, an extra bulkhead was added to subdivide the electrical dynamo room, bringing the total number of watertight compartments to seventeen. Improvements were also made to the ship's pumping apparatus. These modifications meant that Olympic could survive a collision similar to that of Titanic, in that her first six compartments could be breached and the ship could remain afloat.[80][81]
At the same time, Olympic's B Deck underwent a refit, which included extra cabins (the parlour suites which proved popular on Titanic were added to Olympic), more cabins were fitted with private bathing facilities, and a Cafe Parisian (another addition that had proved popular on Titanic) was added, offering another dining option to first class passengers. With these changes, Olympic's gross tonnage rose to 46,359 tons, 31 tons more than Titanic's.[82]
In March 1913, Olympic returned to service and briefly regained the title of largest ocean liner in the world, until the German liner SS Imperator entered passenger service in June 1913. Following her refit, Olympic was marketed as the "new" Olympic and her improved safety features were featured prominently in advertisements.[83][6] The ship experienced a short period of tranquillity despite a storm in 1914 that broke some of the First Class windows and injured some passengers.[84]
-
Like if you look at the quality of the food at the buffet and main dining room, there really is a very heavy temptation to seriously cut food quality and make the food barely edible at the complimentary and get rid of things like lobster nights, in order to force people to eat at the specialty restaurants because the food at the free venues is so bad, so that the cruise lines can make more money from the specialty restaurants, or do things like charge 5 dollars for a glass of tap water.
-
How many cruise ships now in operation can reach at least 25 knots maximum speed, which is consider very fast for a mere cruise ship? I recall the Superstar Virgo reaching 25.5 knots when she was brand new back in 2000, but she is more than 20 years ago now, so I doubt if she can still reach 25 knots. I exclude the Queen Mary 2 here since she is an ocean liner.
-
Who is particular is Holland America line targeting? I mean looking at their ships I can see the benefits of adding water slides and rock climbing walls. The kids had tag along with their parents and grandparents would certainly find it enjoyable. And middle ages people might even find it to be a good addition
-
How is cruising now different from 25 years or 20 years ago? I remember going on board Star Cruises back in 2000, and compared to my experience with Celebrity in 2014 and HAL in 2016 in Alaska, I really did not recall anything different. Are cruises for the same company now cheaper in inflation adjusted terms that they were in 1995 or the year 2000?
-
Why does MSC cruises get such relatively poor ratings? I understand that it is regarded as an economy cruise line, but then so is Carnival, Royal Carribean, and NCL, but they get a lot better ratings compared to MSC.
-
Excluding the luxury cruise lines like Crystal, which mass market cruise line has the worst food for the price? Basically which cruise line has the worst food considering how much you pay for the cruise?
-
Why doesn't it run a 6 day Southampton to New York service like it did in the late 90s or early 2000s? I mean with oil at a reasonable 60 dollars a barrel it could make economic sense to have a fast Transatlantic service again, or Cunard could build a fast LNG ocean liner aguan with more economical gas turbine engines with a 35 knot top speed that could cross the Atlantic in 5 days like the QE2 used to do until 1997.
-
Xenomorph infestation?:eek:
-
In line with the numerous complaints recently about the lack of maintenance in some of HAL's older ships, like those built in the late 90s and older, how much additional maintenance does it cost to keep something built in the late 90s like the Rotterdam or Volendam, or an older ships built in the early 90s like the Maasdam in very good condition, vs. a ship built in the mid 2000s? How much must this add to the fare a passenger pays vs. a newer ship built in 2005? I should note that I was on the Volendam last year and did not see anything like leaky roofs and cracked glass windows or anything like that, and that our outside cabin was in top condition for a 16 year old ship. Also Carnival has a lot of older ships built from 1990 to 1998 or so, do these ships also have the same maintenance issues in their facilities as the older HAL ships?
-
So might be an economics related question, but in opinion of the people here, what jobs in a cruise ship are likely to be impacted most by automation? I know that cruise ships try to practice labor arbitrage by hiring from third world countries, but eventually the cost of automation will be so low that it will be be cheaper than even using Indonesians or other people from 3rd world countries, so what jobs will be most likely to get replaced, like robot cooks and self order kiosks?
-
How is HAL's 14 day Great Land Explorer cruise? What is the best month to see glacier calving? I went on HAL's 7 day Alaska cruise on the Volendam and am thinking of booking again in 2018, how is the Amsterdam? I was on the Volendam and found it to be an OK ship despite being 16 years old, and Amsterdam is about the same age. Any affordable 4 star hotels people would recommend in Seattle?
-
OK so if you look at the prices, HAL/Princess/Celebrity is more expensive than RCL/Carnival/Norweigian, so where does the difference in price go to? Better quality tea and coffee? Better quality ice cream or steak/meats or yoghurt? I noticed that in HAL there is a conditioner in the dispenser versus only shampoo and bath gel in Carnival.
-
Just a question about the extension cord.
On our recent Eurodam cruise, we borrowed a HAL extension cord for free, but would have to pay $30 if it was not returned. Was it different for you?
They charged us 30 for the extension cord on the bill. It was the Celebrity Century, I cannot recall us being on a lifeboat drill calling for us, actually I cannot even recall there being a lifeboat drill, just someone in a lounge giving us some sort of briefing.
-
Well I was on the Volendam, and from what I see I do not see any reason to change, I mean HAL may appeal to the 60 plus demographic but remember that based on demographic projections the over 60 demographics of the US and Europe is expected to grow as a percentage of the population, and anyway that it the demographic that actually has the money to spend, not cash strapped millenials working in Starbucks or Subway.
-
So from the reviews it looks like a lot of people are unhappy with the koningsdam, so what can HAL do to right the ship? It seems it tried to cram too many passengers into the ship with too few crew relative to other HAL vessels, so maybe either increase the number of crew or reduce the number of passengers? Though the 2nd option would increase ticket prices. People also seem to be complaining about the horrible ergonomics of the bathrooms and the rooms being too small in general, plus not large enough space for things like the library and Explorations Cafe.
CODAG vs. COGAG vs. Diesel Ship
in Ask a Cruise Question
Posted · Edited by ren0312
Interesting, since the newer frigates of European navies like the Saschen class and FREMM use CODAG and CODLAG instead of a pure turbine setup. Although unlike the US they do not have 30+ knot carriers to keep up with.