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Will HAL ever have mega ships?

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6 minutes ago, chengkp75 said:

So, you don't measure a ship's displacement until it is launched?  Without knowing the displacement, and the shape of the hull, you don't know the center of buoyancy, and therefore you don't know the stability of the vessel.  Then how does the flag state or the class society know that the ship is safe?  Not so voila.

 

 

I thought we were, slightly of topic, discussing metrics to decide which ship is big and which is small. Why are you saying that I said that no calculations are needed before a ship is launched? I'm trying to decide if it's a red herring or an insult.

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2 hours ago, AmazedByCruising said:

Every time the ship is in a dry dock, displacement can be measured. It's just the amount of water that you don't need to pump out. Just like you explained. Put an official stamp on the results, et voila, there's a simple metric to decide which ship is big and which is small. 

From this statement, how would you calculate displacement in the first place?  If not until the ship is built and in a drydock ready to be launched, how does your method calculate displacement originally?  No one calculates displacement after newbuilding, unless there is a major change to the amount of material added to the ship.  Additionally, displacement at various waterlines (drafts) and trims (both fore and aft and side to side) are used to create tables where the ship's officers and designers can determine the effect of loading 100 tons of cargo, fuel, or food at various spots around the ship, and the resulting change in trim or stability caused by these changes.  These are the figures known in ship stability as "mt1" (moment (weight and longitudinal position) needed to change fore/aft trim 1 inch or cm), and the "tpi" or "tons per inch" meaning how much does 1 ton of weight affect the draft of the vessel.  So, unless you are figuring on docking and undocking a ship repeatedly at various drafts and trims, you have to use the volume calculations done at design to find this information.

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In one post you say that calculation of displacement is absolute necessary for the class society (which I do believe). In the next you say that nobody calculates displacement for a new build (which I don't believe). All I wanted to know is why "enclosed volume" gets the importance where the simplest divide between a big and a small ship is obviously it's weigth.

 

Let's just leave the subject. 

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2 hours ago, AmazedByCruising said:

All I wanted to know is why "enclosed volume" gets the importance where the simplest divide between a big and a small ship is obviously it's weigth.

 

Could it be that enclosed volume is a relatively trivial calculation compared to weighing a ship, especially one that hasn't been built?

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11 hours ago, AmazedByCruising said:

In one post you say that calculation of displacement is absolute necessary for the class society (which I do believe). In the next you say that nobody calculates displacement for a new build (which I don't believe). All I wanted to know is why "enclosed volume" gets the importance where the simplest divide between a big and a small ship is obviously it's weigth.

 

Let's just leave the subject. 

No, you said to calculate displacement using a drydock.  I asked how you calculate displacement before a ship is in drydock, as that calculation is required for stability.  Your method seemed to be to measure displacement after construction.  Here is what I said:

 

On 7/7/2019 at 2:53 PM, chengkp75 said:

No one calculates displacement after newbuilding, unless there is a major change to the amount of material added to the ship. 

I've added the bolding to the important word you missed.

 

Now, as a final example:

 

Oasis of the Seas:  225,000 GT, approx 100,000 tons displacement, 361 m length, 47 m beam

 

TI Asia:  234,000 GT, 67,500 tons displacement (empty), 380 m length, 68 m beam

 

Which is "bigger"?

 

And, to further confuse the issue, when fully loaded, the TI Asia has a displacement of 509,000 tons. So, the same ship can be either half the weight of Oasis, or 5 times the weight.  This is why different tonnages matter to different types of ships.

 

And with that lets leave it to a Naval Architecture course to explain further.  It's been too many years.

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6 hours ago, chengkp75 said:

And, to further confuse the issue, when fully loaded, the TI Asia has a displacement of 509,000 tons. So, the same ship can be either half the weight of Oasis, or 5 times the weight.  This is why different tonnages matter to different types of ships.

 

Yes, that certainly is confusing. I hope to understand correctly that it doesn't matter for GT if a container is put on the deck, however when you weld it to the deck GT changes. 

 

6 hours ago, chengkp75 said:

And with that lets leave it to a Naval Architecture course to explain further.  It's been too many years.

 

OK. Thank you as always for explaining!

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9 hours ago, chengkp75 said:

No, you said to calculate displacement using a drydock.  I asked how you calculate displacement before a ship is in drydock, as that calculation is required for stability.  Your method seemed to be to measure displacement after construction.  Here is what I said:

 

I've added the bolding to the important word you missed.

 

Now, as a final example:

 

Oasis of the Seas:  225,000 GT, approx 100,000 tons displacement, 361 m length, 47 m beam

 

TI Asia:  234,000 GT, 67,500 tons displacement (empty), 380 m length, 68 m beam

 

Which is "bigger"?

 

And, to further confuse the issue, when fully loaded, the TI Asia has a displacement of 509,000 tons. So, the same ship can be either half the weight of Oasis, or 5 times the weight.  This is why different tonnages matter to different types of ships.

 

And with that lets leave it to a Naval Architecture course to explain further.  It's been too many years.

Do we receive credit for the course, or are we just auditing?

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On 7/2/2019 at 3:14 PM, cruisemom42 said:

When I first joined these boards, people were still wailing because HAL was building ships in the Vista class size range. That range was not so far from the "largest" ships of the period. It seems to me there is inevitable creep in size in the mass market segment of cruising, and HAL will likely try to maintain its precarious position of building "smaller" ships than the mega-monsters. However, to me a 5,000 passenger ship doesn't seem "small" just because they are building 7,000 pax ships. It's marketing and semantics. It will be interesting to see if, 10 years from now, people are here saying "I won't ever go on any ship over 3500 passengers. No jumbo ships for me."

 

As Kazu has pointed out several times, with the sale of Prinsendam, HAL lost quite a few unique ports. The remaining ships do not take up that slack. While HAL still offers some good itineraries, there are places HAL ships can no longer go. 

 

These are the unfortunate realities of "keeping up with the [mass market] Joneses."  I don't fault HAL, but that doesn't mean I will sail on any mega-ships either, just because they have a blue hull....  

 

Great points.  We were just in Norway and so many of the ports were overwhelmed by mega ships. Would love to visit smaller ports with fewer tourists.  

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grt - one fact I did not see mentioned.

When I went to sea in 1964 about 10 years before containerisation - we learnt that 100 cubic feet = 1grt. 

Ship owners had many dodges to reduce grt uncluding Shelter Deck general cargo liners that I sailed on. Also the funnel / stack & other non watertight spaces were not included in grt.

Metrification & to remove the cheating GT was born.

To download a great explanation by an Australian marine pilot see --

wss-vic.org.au/articles/marine_glossary.pdf

 

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