Chinese river ship launch failure

Some of the above have only a stern sponson added, so there seems to be a prior lack of buoyancy aft.

Maybe the side sponsons have been added due to extra safety requirements, to provide extra stability and prevent capsizing when water enters the cardeck, after disasters such as the 1987 capsize of the Herald of Free Enterprise when leaving the port of Zeebrugge, killing 193 passengers and crew.


pic thanks to Jan Dewachter

Herald Of Free Enterprise capsizing (3D animation)

Well, no cheers now
Angel

 

Yes, the rules changed...
New SOLAS regulation Ch II-1, 8-1 and 8-2 and Stockolm agreement requirements.

 

Wow...

And there is another thread started slightly later regarding this launch failure here as well (threads now merged)

 

They're airbags to roll the ship down the ramp when launching. In above vid there were to little or they were to light as you hear them bang.

Here the launch of a LPG tanker, on the Danube in Romania, on those rolling airbags - Link - Link - Link - also some problems.

( P.S. - see note about this in post #54 )









They were also used to launch the Chinese ship in the vid in post#1, info about that here - Link - Link -

More links to airbag ship launchings - Link - Link - Link -

Cheers,
Angel

 

Here Marine Airbags Feb. 1, 2010 record:

Cheers,
Angel

 

Yes, I spent about three hours thinking about these contraptions engineeringwise. It reminded me about a quote regarding a dancing dog- What is amazing is not how badly it's done but that it's done at all.

 

Didn't really 'sink'; the idiots just stuffed it arse-end into the water at too steep an angle. Even I could've told them that wasn't a good idea...

But for some reason, they didn't check with me first.

 

Thanks, just checked the timeline...

1987, the Herald of Free Enterprise, 193 dead was a clear warning, and even before this disaster the stability problems when water enters the uninterrupted all over the ship cardecks were well known. But they waited for the 1994 Estonia disaster to change the rules. Of the 989 people aboard only 137 survived.

The Sinking of Estonia





Who's gonna blame China for mishaps

Cheers,
Angel

 

They were different types of accidents...

Anyway "a posteriori" it's always easy to say what should have been done. Are present regulations safe and fool proof? Yes, until another accident happens... Neverthless we have coming a long way since Titanic and subsequent first version of SOLAS and shipping is a heavily regulated industry but sometimes the sea, and the human being, refuses to cooperate.

The unsinkable ship is still to be built...

 

Anyone knows what is the inflation pressure inside those bags?

Edit:
Ok, found it. They work with pressures up to 1.4 atm - surprizingly small. Looked like rolling bombs at first glance, but they are actually less inflated than car tyres.

 

The roll-on roll-off ferry type built as those ferries was already under fire before the disaster of the Herald of Free Enterprise, which was more than seven years prior to the Estonia disaster, because of the large continuous car decks over the whole length and breadth of the ship to enable quick on and off load.

Once such a ship makes water the all over the ship free float liquid surface rapidly decreases the stability and causes a very rapid capsize. Both disasters, the Herald of Free Enterprise and the Estonia, started with water entering trough the bow door causing the above.....

‘‘ Are present regulations safe and fool proof? Yes, until another accident happens... ’’

The lesson here to learn is that one doesn't have to wait for a second accident to change the rules..

Cheers,
Angel

 

Back to the bags...

- whats the empty weight of a ship like the one in post#18 per cm² bottom surface . . ? ?

- how much of the bottom surface is covered by the bags . . ? ?

- is the 1.4 atm just pre-pressure or working pressure when loaded with the ship . . ? ?

- if 1.4 atm is pre-pressure, what's the pressure when max loaded . . ? ?


• The quick question is, does such a ship weight less than let's say 0.5 kg per cm² bottom surface . . ? ?


Cheers,
Angel

 

1.4 atm is (according to the site linked below) the max working pressure, so with the ship pushing down on the bag.
http://www.blueoceantackle.com/ship_launching_air_bags.htm

 

did anyone mention the megayacht in bangkok as well?

 

From Daiquiri's link . . . .

OK, while rolling it's 0.12 MPa (~1.2 atm), it says that gives a ø 1,5 m x 15 m bag 234-tons carrying capacity.

That seems to be a bit optimistic as . . . . 234,000 kg / 1.2 kg/cm² / 1,500 cm = 130 cm

Which means that the ø 1,5 m x 15 m roll on top and bottom surface is flattened to 1.3 m wide to carry the 234 tons at 0.12 MPa.

Flattened roll hight will be: (π x 1.5 m - 2.6 m) / π = 0.67 m

Flattened roll wide will be: 0.67 m + 1.3 m = 1.97 m

That seems to be a bit flat to roll well, even if the roll will deforme well while rolling.

It's even a bit worse because the surface lost in pointed ends is not included in the calculation.

But what's the weight of that ship in post#18 . . ? ? - I need an NA to estimate that

Cheers,
Angel

PS - it doesn't show well, but . . . π = pi