WHY DID COSTA CONCORDIA CAPSIZE? - Explaining the ship's stability using the official report

hello and welcome to today's video where we're asking why did the cost of concordia capsize and to answer that we're going to be looking at the official accident report published by the italian authorities so the official accident report actually runs to a full 174 pages now we're not interested in the entire report we're actually only interested in a single paragraph that paragraph details the second grounding flooding and stability phases and what it does is it breaks the events down into a sequence of four firstly the ship listing over to port due to the damage he sustained next symmetrical flooding which led to the ship's writing third the listing over to starboard due to the effect of wind and finally the complete loss of stability that led to our cap size and leaning right the way over on a starboard side so we're going to look at the overview chart of the area we got the chart and the wind overlaid in an east north easterly direction at 17 knots the ship is running towards the island she takes a long sweep round to starboard until eventually she makes contact with the land on her port side in this position to actually see what happened to the ship itself we're going to be using the same diagram that i've used in previous videos if you haven't already seen those i would advise checking them out first because we're going to be expanding on those concepts to explain this sequence of events firstly we need to overlay the centre of gravity and center of buoyancy then we can put on arrows for the forces that are acting through these we know the force of gravity is acting straight down through the center of gravity and the force of buoyancy acting straight up through the center of buoyancy now when these are in line the ship is perfectly upright and she's quite happy but when we get that impact on the port side it leads to the immediate flooding of all those tanks out on the port wing the same time the larger tanks down the bottom gradually start to flood all this additional weight drags the centre of gravity off the center line it actually moves towards those additional weights once the center of gravity and center of buoyancy are no longer in line the ship will have to lean over until they line up again but look at what's happened to the water in that tank down the bottom it looks like it's all collected over on the port side the water has actually stayed flat but the tank it's in has rotated we call this effect a free surface effect and what it actually does is it drags the center of gravity even further out to port which would lead to the ship leaning even further over to port while those tanks are partly filled now of course as the ship continues to sink we know those tanks do fill up and as they fill up they actually increase the ship's stability bringing the centre of gravity back towards the center line now in the real situation it wasn't just tanks that this happened to the same effect occurred throughout the entire engine room you can imagine the free surface effect of water across the full width of the ship so we've seen that the initial impact led to the ship leaning right the way over to port during the next phase we know that she drifted round her engines were no longer running because the engine room had been flooded but she continues to drift round swinging out to starboard now that swing is just coincidence because of the direction of the wind and the fact that the last helmholder was over to starboard and that is where the rudder stopped when they lost all control during this phase cross flooding occurred which led to the gradual writing of the vessel itself cross flooding valves are built into the ship's design what they're designed to do is to let those starboard tanks flood in the event of a hull breach like this one that we've seen allowing those tanks to fill up with water drags the centre of gravity back towards the center line as that drags it back towards the center of course the ship starts to come upright eventually if you let all the all the tanks on the starboard side flood the ship should in theory be sat upright again theoretically by the time she ended up in this position bow to wind she should have been sat perfectly upright but she carried on turning round slightly and then the wind caught the bow and she started blowing sideways towards the land without any other influences the ship could have just continued to sink vertically straight downwards this would have allowed the launch of all the boats with the ship sat perfectly upright we know the wind was blowing on the port side this will have lent the ships slightly over to starboard you combine that with the free surface effect of all that additional water and the ship actually starts to develop a starboard list now at this point it's not that severe and if she had continued like this again all the boats could have been launched and she would have continued to sink vertically straight downwards as she's sinking with that slight starboard lift she continues towards the land though until eventually she touches the bottom and she grounds in this position here as soon as she grounds the stability situation changes entirely let's have a look down at the bottom and think about what happens we know if the ship touches the ground it's exerting a force onto the ground itself and because of newton's laws we know that the ground is exerting an equal and opposite force onto the ship we can imagine a force being exerted straight up onto the ship in this position here for stability we think of it as a negative mass and the effect that it has is it raises the center of gravity if you're taking off a negative mass from the bottom the center of gravity is going to have to go up to compensate for that once that centre of gravity raises up this is when the ship experienced the complete loss of stability you can see the buoyancy and gravity arrows are no longer in line they're acting just to continue to tip the ship over and she'll continue all the way over until she eventually ends up resting right the way over on her starboard side having explained it throughout we can now imagine the full sequence of events the ship is continuing towards the island she's okay at this point and then she starts to turn to starboard at this point she's sat upright but then she makes contact with the island immediately a lot of weight comes on the port side and she lifts right over to port during the next phase where she's drifting forward cross flooding occurs gradually righting the ship until she sat almost upright then the wind catches her on her port side and induces a small list over to starboard which gradually increases eventually she makes contact with the bottom and grounds on the island itself and that act of grounding actually means that the ship continues right the way over onto a starboard side and lays in the final position that we're all so familiar with and that brings us to the end of this video hopefully you found the information in it useful and informative if you have a thumbs up is always appreciated if you've got any questions or comments just leave them below and if you'd like to keep up to date with all videos that i publish make sure you hit that subscribe button until next time thank you for watching and goodbye

Channel: Casual Navigation

Views: 926,474

Keywords: costa concordia, costa concordia accident, costa concordia capsize, ship capsize, why did concordia capsize, costa concordia sinking, costa concordia sink, casual navigator, cruise ship capsize, cruise ship sinking, costa concordia disaster, ship, cruise, sinking, francesco schettino, costa cruises

Id: XvPxFx5IomY

Length: 8min 8sec (488 seconds)

Published: Fri Mar 16 2018