MSC Opera Crashes into Riverboat in Venice

[Beamafar]

 

2 minutes ago, capriccio said:

 

I say this as an avid cruiser but also as someone who lived in Italy for 5 years in the 70s and 80s:  it is the cruise ships that unload thousands (tens of thousands on a busy port day with the mega ships) of people and have overwhelmed the capacity of the cities and their attractions to handle them. 

 

We returned to Italy for an extended vacation - to show our now grown kids where they were born - in 2011 and were absolutely stunned by the number of tourists (including us!) in Florence, Rome and Venice.  Talking to locals in every city, they all mentioned the number of cruise passengers as being the biggest contributor.   We had a great vacation but my parting words to my kids were "Come back in the middle of winter.  The weather won't be as nice but your sightseeing will be much, much better."

 

This is the problem that many, many towns and cities in Europe have now.  Those who go on holiday to these places and stay in hotels, etc, are finding it challenging to enjoy the facilities and attractions due to cruise ship passengers descending on the places in hordes each day.

 

The situation is set to worsen even further over the next couple of years, what with all these new, behemoths being built and the increased numbers of passengers as a result.

[broberts]

1 hour ago, Domen said:

 

That is true to some point. It all goes down to wave height.

As a Civil Engineer I had studied the Hydromechanics and the sole culprit for the destruction of shore is based on the force of the wave hitting the shore (kN/m2). ...

 

It occurs to me that while wave force may be the sole destructor of shoreline, a Venetian canal has a somewhat different composition. Would this not make a difference?

 

51 minutes ago, DerekB said:

I am curious - when I watch the cruise ships drive by I am about 100 meters from them. There is no way the waves that come to shore are anywhere remotely near 3.4 meters. They would be more on the scale of the .35 meter waves. Any idea what accounts for this difference? It seems the shipping vessels (Which are much smaller) and speed boats cause FAR higher wave heights. Just curious and you seem to be the expert for sure!

 

Would not the confines be a significant factor? A relatively narrow canal is going to restrict water displacement and result in a higher wave than a wider body of water.

[old nutter]

4 minutes ago, broberts said:

 

It occurs to me that while wave force may be the sole destructor of shoreline, a Venetian canal has a somewhat different composition. Would this not make a difference?

 

 

Would not the confines be a significant factor? A relatively narrow canal is going to restrict water displacement and result in a higher wave than a wider body of water.

In the case of Venice, the problem is below the water line.  There is massive current turbulence from the movement of the water being displaced by the hull.  The water that was where the hull of the ship was has a few seconds earlier before the ship came along to go somewhere and as the hull moves along, that lump of water from the whole space is squeezed away causing substantial currents and turbulence for the whole depth, not just a bit of stirring at the surface.  As has already been explained, the height of the wave is more dependent on the speed of displacement than size, but the destructive force created by the massive movement of water throughout the depth of the hull is more destructive to the underwater environment than the waves are above it.

[sidari]

MSC Opera has been declared fit to sail but Italian authorities are still holding the ship while investigations continue.

The next cruise as some may be aware has been cancelled.

[Rocchi]

I have also been in Venice and watched the ships sail in and out and observed that no bow wake comes from the ship as their speed is very low and is regulated by the tugs and the pilot. meanwhile the small car ferries and the water buses and everything else smallish are charging about causing all the wash and waves regardless.

 

Right, so, did a couple of sums to see what the actual ships displacement would be compared to the volume of water in the Giudecca canal.

 

Width of canal at narrowest point (round about where she had the accident 240 meters

Depth of the canal 9 meters

Length of the ship 250 meters

 

All multiplied comes to 540,000 cubic meters or about the same in tons

 

The dead weight of the MSC Opera is given as 2,620 tons or about the same in cubic meters

 

Divide one in to the other and I get 206.11 times the volume of water to the volume of the ship.

 

It appears to me that there is plenty of space for the displaced water to to get out of the way of a ship crawling along the middle of the canal without any heavy surges out of the sides of the ship.

 

For reference as comparison the Oasis of the Seas dead weight (one of the biggest) is given as 15,000.

 

If anyone else thinks this a a load of nonsense, that’s fine.

 

I don’t believe the cruise ships are causing any damage to Venice or her canal infrastructure. However I do not think any cruise ships should enter Venice through the Giudecca canal. It looks excessively weird to see these huge thing sailing past the entrance to St. Mark’s square. I will not comment on what the solution to the problem should be, that’s for the Venetians to do something about it, if they really want to and in the process lose a whole heap of business.

[sidari]

Has anyone taken into account the average depth of the canal ? While it may be 9 metres in the sailable channel closer to the sides it may be considerably less.

Any water moved forward by the ship would be pushed towards the canal used by commercial traffic going into the port.

 

[chengkp75]

1 hour ago, Rocchi said:

I have also been in Venice and watched the ships sail in and out and observed that no bow wake comes from the ship as their speed is very low and is regulated by the tugs and the pilot. meanwhile the small car ferries and the water buses and everything else smallish are charging about causing all the wash and waves regardless.

 

Right, so, did a couple of sums to see what the actual ships displacement would be compared to the volume of water in the Giudecca canal.

 

Width of canal at narrowest point (round about where she had the accident 240 meters

Depth of the canal 9 meters

Length of the ship 250 meters

 

All multiplied comes to 540,000 cubic meters or about the same in tons

 

The dead weight of the MSC Opera is given as 2,620 tons or about the same in cubic meters

 

Divide one in to the other and I get 206.11 times the volume of water to the volume of the ship.

 

It appears to me that there is plenty of space for the displaced water to to get out of the way of a ship crawling along the middle of the canal without any heavy surges out of the sides of the ship.

 

For reference as comparison the Oasis of the Seas dead weight (one of the biggest) is given as 15,000.

 

If anyone else thinks this a a load of nonsense, that’s fine.

 

I don’t believe the cruise ships are causing any damage to Venice or her canal infrastructure. However I do not think any cruise ships should enter Venice through the Giudecca canal. It looks excessively weird to see these huge thing sailing past the entrance to St. Mark’s square. I will not comment on what the solution to the problem should be, that’s for the Venetians to do something about it, if they really want to and in the process lose a whole heap of business.

The problem with your calculations is that "dead weight" is not the weight of the ship, it is the weight of things the ship can carry (fuel, water, food, passengers).  Wiki:

 

"Deadweight tonnage (also known as deadweight; abbreviated to DWT, D.W.T., d.w.t., or dwt) or tons deadweight (TDW) is a measure of how much weight a ship can carry,^[1][2][3] not its weight, empty or in any degree of load. DWT is the sum of the weights of cargo, fuel, fresh water, ballast water, provisions, passengers, and crew.^[1]

 

  The weight of a ship is its "displacement, and while this number is rather hard to find on public access, a ship the size of Opera will have a displacement of 25-30,000 tons (or cubic meters) (if you take her length x beam x draft, which is the "hole" in the water she displaces, that is 50,000 cubic meters, but round down for pointy bow, etc).  So, the canal is only 18 times the volume of the ship.

 

And, for comparison, the "displacement" of Oasis of the Seas is about 100,000 tons.

 

Additionally, even at slow speeds, there is the phenomenon known as "canal effect" where the combination of ship speed and current (and I don't know the current in Venice) can combine in a narrow channel or close to the side of a sharply defined channel (I would think the buildings directly along the canal would mean there is a sharply defined side to the channel, and she was close to the side) creates a low pressure or "venturi" alongside the ship, which has been known to suck moored ships away from docks.  So, this low pressure is another pressure wave the ship creates as it passes.

 

By the way, did you really think a ship the size of Opera only weighed 2500 tons?  Must be some really high strength steel to get by with that little weight.  I can guarantee that she carries about 1000 tons of fuel oil alone.

Edited June 6, 2019 by chengkp75

[sidari]

Cheng ... I would guess that as water is virtually incompressible that the issue of displacement in a narrow canal becomes worse as it becomes shallower and narrower.

[Rocchi]

Cheng.

 

Thanks for the corrections. I have no idea of the physical weight that a ship might be.

[chengkp75]

1 hour ago, sidari said:

Cheng ... I would guess that as water is virtually incompressible that the issue of displacement in a narrow canal becomes worse as it becomes shallower and narrower.

Yep.

[fstuff1]

9 hours ago, chengkp75 said:

By the way, did you really think a ship the size of Opera only weighed 2500 tons?  Must be some really high strength steel to get by with that little weight. 

 

space age ceramic polymer alloys with a weight of a feather? 

[muggo11]

On 6/5/2019 at 8:47 AM, sidari said:

Would have been Costa itself I would reckon.

 

Actually, if you read the Carnival Corp’s annual report for that year, the financial hit to the parent corporation is on its balance sheet. Don’t know about all the liability issues, though. 

Edited June 7, 2019 by muggo11

[gatour]

On 6/6/2019 at 1:43 AM, Domen said:

Regarding the ban on cruise ships in Venice... I hope that the ban (if implemented) would include a grace period (for those who already booked). I hope there won't be a "Cuba" scenario.

 

But what I am more concerned about is the ripple effect of this decision. Which city would be next to ban the ships? Probably Dubrovnik, maybe Barcelona. Those cities are already packed by tourist in high season.

Doubt it will be Barcelona.  It is a major embarkation/disembarkation port.  In fact over the last several years Royal Caribbean has had an Oasis class ship based there during the summer.

[daveispar]

On 6/6/2019 at 7:30 AM, capriccio said:

 

I say this as an avid cruiser but also as someone who lived in Italy for 5 years in the 70s and 80s:  it is the cruise ships that unload thousands (tens of thousands on a busy port day with the mega ships) of people and have overwhelmed the capacity of the cities and their attractions to handle them. 

 

We returned to Italy for an extended vacation - to show our now grown kids where they were born - in 2011 and were absolutely stunned by the number of tourists (including us!) in Florence, Rome and Venice.  Talking to locals in every city, they all mentioned the number of cruise passengers as being the biggest contributor.   We had a great vacation but my parting words to my kids were "Come back in the middle of winter.  The weather won't be as nice but your sightseeing will be much, much better."

All of us tourists can be a problem, but, be careful what you ask for.  What percentage of all the workers in all the tourists locations in Europe depend on tourism for their jobs ?  I don't know, but, without tourism Europe would be in deep trouble.  As would many other places in the world.  What's the solution,  I don't know, but,  they need to have one in place before doing something drastic. 

[DownByTheSea]

On 6/5/2019 at 11:43 PM, Domen said:

 

But what I am more concerned about is the ripple effect of this decision. Which city would be next to ban the ships? Probably Dubrovnik, maybe Barcelona. Those cities are already packed by tourist in high season.

 

Just got back from a cruise that stopped in Dubrovnik. Super crowded of course. Funniest bit was when the local Game of Thrones Tour guide guy referred to the hoard of cruise people as White Walkers. 😁

[beg3yrs]

On 6/6/2019 at 6:59 AM, Domen said:

 

That is true to some point. It all goes down to wave height.

As a Civil Engineer I had studied the Hydromechanics and the sole culprit for the destruction of shore is based on the force of the wave hitting the shore (kN/m2). That force is calculated only by wave height. That means that wave 1m high coming from cruise ship has the same force as 1m wave coming from speed boat. Problem is that cruise ship can generate a wave 1m high at low speeds, but small boat needs a lot more speed.

 

The equation of maximal wave height that a water craft generates is down below (height of wave hitting the shore). 

Hm is maximal wave height [m], V is speed [m/s], X is distance between shore and boat [m], Lv is length of the boat at waterline [m] and D is draught [m]

 

So MSC Operas maximal wave (2 knts and 300m from shore) is 3.4m. This is theoretical height of course. Small boat (10m long, 10 knts, 1m draught and 30m from shore) will generate only 0.35m high waves.

 

From this equation, the wave height is inversely proportional to V, the speed. I believe that's an error as one would expect the faster you travel, the larger the wave...

[mnocket]

57 minutes ago, beg3yrs said:

 

From this equation, the wave height is inversely proportional to V, the speed. I believe that's an error as one would expect the faster you travel, the larger the wave...

 

Good catch!  Something seems amiss here.

[luisrp]

Just out of pure luck caught MSC Opera sailing out of Venice.  Likely departed at 10:30 PM local time.

 

[luisrp]

 

 

 

These images were captured from these cameras.

https://www.skylinewebcams.com/en/webcam/italia/veneto/venezia/riva-schiavoni.html

https://www.skylinewebcams.com/en/webcam/italia/veneto/venezia/san-giorgio.html

 

It is worth noting that cruise ships are now being escorted by two tugs in front plus the usual one behind.  They now use three tugs to get ships in and out of Venice.

[sidari]

3 Tugs has been in since the incident.