Posted on 03/25/2019 10:18:09 AM PDT by C19fan
I frankly don’t know how they do it, or the RORO’s (Roll On-Roll Off ships).
It’s ALL sail area too.
G (Center of Gravity) cannot be above M (The Metacenter of the ship)
What is the Metacenter?
It’s an imaginary (but real) point that defines a measurement called ‘metacentric height’. This is the distance between G and this point M. G needs to be below M, or the ship has no righting moment. If G and M are in the same place, then the righting moment is zero, and any unbalanced lateral force will make the floating object list, or roll, and it will not recover.
Think ‘log’. A log is a boat in which G and M are in the same spot.
If M is below G (Put a lot of weight above G, and you will achieve this), then the boat will roll over on its own and maintain that state (capsize).
I’ve never been on a cruise ship as a passenger. I saw some footage where large pieces of furniture were not secured to the deck, and they were just sliding about.
Somehow, in all of this, M stayed above G. A tanker diverted to try and help the cruise ship, but IT lost power too. Very strange. Must have been a hell of a storm.
It’s Norway, and the only condition I can think of that would cause a loss of propulsion in two separate ships of random large classes would be a loss of raw water suction due to the sea chest clogging with ice.
I don’t think that happened.
The genius’ that built the USCGs two Polar Class breakers designed sea chests that clogged all the time with ice. Annoying.
Apparently you were unhappy with my posting of the facts.
Please cite otherwise.
Good question of yours, why did all 4 engines stop.
Basic diesel engines will always run if there is fuel feeding and if there is not any air in the fuel lines. It’s that simple. They are totally mechanical, no electricity required to keep running. Modern diesels though almost always have electronics involved and a loss of electricity or a blown circuit board will shut down the engine.
In this case though all 4 engines shut down so I would go with the basics and guess that the violent seas and thus ship rolling and pitching either 1) stirred up gunk in the main diesel tank that royally fouled filters or bypassed centrifuges and plugged injectors or 2) sucked a lot of air into the fuel lines that overwhelmed filters and centrifuges.
The got 3 of the 4 engines after 24 house or so. This also supports a fuel supply related problem that took awhile to fix.
Since I don’t know the exact CG specs of this vessel, that would be hard for me to do. However, I can refer you to the Handbook of Damage Control, NAVPERS 16191, Chapters III, IV, VI, and IX, which describer the forces affecting transverse stability of seagoing vessels.
Why the snark?
“Since I don’t know the exact CG specs of this vessel, that would be hard for me to do. “
But it was easy for you to say it would absolutely tip over ….
Yeah, but not with 1300 passengers.
No argument from me there.
In February of 2006, a Princess Cruise liner experienced a similar problem and took on a list. The media, exaggerating as usual, said the vessel heeled to 45 degrees. A spokesman said that was unlikely, since the ship could capsize if the list exceeded 24 degrees.
I belive the pbraze I used was “unlikely.”
Do you know the righting moment of this ship? If not, you don’t know that I’m not right.
“I belive the pbraze I used was “unlikely.”
Don’t lie. The internet is forever.
“Do you know the righting moment of this ship? If not, you don’t know that I’m not right.”
I know the design requirements. You are wrong.
You may be correct but I have not heard that the ship lost power just propulsion. That would point to a problem with electrical power to the AZIPOD propellers, which I believe this almost new ship has.
Same captain as the Duck Boat guy who sailed his flimsy ship into an oncoming storm?
Reread the post.
Are you seriously trying to argue that a vessel as topheavy as a cruise liner can take on a sustained list of 45 degrees in heavy seas and high winds, with no propulsion, and not be at risk of capsizing?
In the cruise ship world, Itinerary Is God. Nothing else matters- including safety.
Not to mention a calculation of the vessel's Righting Arm Curve.
USCGs two Polar Class ice breakers
One is parts only and the other is kept going with duct tape and wire ...
“Are you seriously trying to argue that a vessel as topheavy as a cruise liner can take on a sustained list of 45 degrees in heavy seas and high winds, with no propulsion, and not be at risk of capsizing?”
You claim you said something you didn’t say and now you are inferring something that i didn’t say, also.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.