What Happened To The Commodore Clipper?

on the 15th of june 2010 the ropex ferry commodore clipper sets out from jersey and the channel islands towards portsmouth in the uk she's a 14 000 ton ferry that can take role on roll-off cargo as well as passengers on this voyage she was carrying 62 passengers 39 crew and had cars and freight trailers on her vehicle decks at 2 42 in the morning of the 16th of june smoke detector activated on the port side of the vehicle deck over the next couple of minutes more and more sensors activated there was a fire on the vehicle deck now before we continue i'd just like to take a moment to thank fire aid academy for making this video possible shortly after 3 am with the fire spreading quickly commodore clipper sounded her crew alert and general emergency alarms ventilation fans which feed fresh air into the vehicle decks were shut down and the drencher system was activated a drencher system is a bit like a powerful shower large pumps send massive quantities of water through sprinkler heads spread throughout the deck the idea is that it rains water down on any fire that's on the deck now the main issue with drenchers is that the volume of water they produce can very quickly impact upon a ship's stability on this diagram we've got our ship the water line and the center line the draft is the distance from the keel to the water line and the free board is the distance from the water line to the highest water type deck next we've got the center of buoyancy which is the geometric center of the underwater volume so on an upright ship it's going to be on the center line we assume that the force of buoyancy acts straight upwards through the center of buoyancy all we've really done is average out how the buoyancy acts on every part of the underwater hull if the ship leans over the underwater shape changes and the center of buoyancy moves there's more hull underwater on this side so the average of all the buoyancy moves in this direction it's still the geometric center of the underwater volume and the force still acts straight upwards the point at which this buoyancy force acts through the center line is called the metacentre notice how at small angles of heal the metacentre is effectively fixed in one position we'll use this in a minute the final thing to add in is the centre of gravity this is kind of like the average position of all the mass within the ship on a perfectly balanced evenly distributed ship it would be in the precise center we assume gravity acts as a force vertically straight down from the center of gravity when the ship leans over slightly notice how the force of gravity and the force of buoyancy separate and create a twisting force acting to bring the ship upright you get a basic idea of it by measuring the distance between the center of gravity g and the metacentre m your gm tells you how stable your ship is you can change your gm by moving the center of gravity as you add cargo on one side the center of gravity moves towards that added weight this is why you want to load ships evenly so the center of gravity remains in the middle as well as from side to side it can also move up and down imagine ballasting a tank at the bottom you've added a large weight low down dragging the center of gravity towards the additional weight you've increased the distance between g and m increasing your gm makes your ship more stable when this ship leans over you can see the force of gravity and the force of buoyancy are much further apart a larger writing force is generated by a larger gm conversely as the centre of gravity rises the writing force reduces then if it gets too high a capsizing force is generated instead when the highest water tight deck gets submerged remember that's the free board from earlier the underwater shape changes and basically you've had it so what is the impact of all of that on our story where we introduce the drencher water to fight the fire as we add more water we're adding more weight further down the centre of gravity moves towards the additional weight increasing the ship's stability but if the ship starts to lean over even a tiny bit the water no longer stays flat it moves towards the low side a greater weight of water is now on the low side shifting the centre of gravity off the center line we call this the free surface effect in a ballast tank you can eliminate the effect by pressing the tank to be completely full so the water can't move on a cargo deck you can't do that instead you need to account for this free surface of water you need to make sure there is enough stability in the vessel so the gm is large enough to cope with the loss of stability due to the free surface effect of course you can always minimize the effect by reducing the water used you apply less water and make sure the water you do apply has a place to drain away in the case of the commodore clipper she's designed with drains at deck level to let the water escape as water rushes to the low side it goes straight out the drains and over the side you can keep the drenches running as long as you like to extinguish any fire in the same way boundary cooling teams on the deck above can apply as much water as they want whatever they apply will find its way straight over the ship's side by 3 40 boundary cooling and the drenchers seem to have bought the fire under control so the vessel continued her passage to portsmouth an hour later at 4 43 the crew noticed that the ship had started to develop a list checking over the side they noticed the outflow of water from the deck drains had reduced the water from the drenchers was collecting on the deck listing the ship over around five degrees to port it turns out a cargo of potatoes had got out of the damaged trailers and they'd been washed towards the deck drains they slowed the outflow of water to such an extent that the deck started to fill up the free surface effect that we discussed a minute ago was having a serious impact on the ship's stability the crew shut off the drenches and the ship slowly returned upright as the water drained away unfortunately the fire was not completely extinguished and smoke gradually returned the crew were forced to restart the drenching system which in turn reintroduced the list once the list reached 6 degrees they had to shut down the drenches again now an issue with the drencher system above vehicles is that there's no way for the water to directly reach a fire inside a trailer the trailer itself provides a certain degree of protection allowing the fire to persist each time the drenches were stopped the fire could take hold again there was nothing now stopping the plastic curtains on either side of the trailers from igniting as well they generated so much heat that more hot spots developed on the deck above while all this was going on on board preparations were made to get the ship into portsmouth harbour under the escort of two tugs she made her way in and docked stern first onto berth 2 chosen because it would be the easiest one to use carefully they opened the stern doors to the vehicle deck there was a concern that opening the doors would allow fresh air into the deck accelerating the fire to reduce that chance the local fire service reposes creating a water curtain that could contain the flames sure enough the fire did grow again forcing the crew to reactivate the drenching system to douse the flames of the smoke this time the stern door was opened so they could trim the ship by the stern and allow the water to flow straight out that way bypassing the blocked drains they could even use the ship's healing system to rocker from side to side shifting any water that accumulated at the edges of the deck over the following hours the ship's crew worked with the local fire service and port authorities to remove the cargo trailers one by one the last effector trailer was finally removed around 9 pm that evening once the immediate situation was resolved attention turned to the post accident investigation this is a critical part of any fire incident because we all want to learn lessons about how to avoid the same thing happening in the future normally this is done by specialist fire investigators but occasionally a ship's crew will be involved as well it's all about collecting evidence and preserving the scene you gather witness statements collect cctv and vdr recordings photographic evidence and prevent unauthorized access to the scene itself as i say this is normally done by specialist investigators who are highly trained in what they do their findings are published in accident reports just like this one this entire video is based on this marine accident investigation branch report the sole purpose of these reports is to prevent future accidents through the ascertainment of its causes and circumstances i'll include a link to the report in the description of this video so you can read the full details of the event yourself and that brings us to the end of today's video again a massive thank you because this video has been produced in partnership with fire aid academy who offer a range of professional maritime courses including sea survival firefighting medical and security courses fireaid have worked within the industry since 1991. visit their website to see the range of courses available at www.firaid.com until next time thank you for watching and goodbye you

Channel: Casual Navigation

Views: 460,724

Keywords: casual navigation, casual navigator, marine, marine animation, maritime explaination, merchant navy, sailing, shipping

Id: QyEv4IsgFo4

Length: 9min 17sec (557 seconds)

Published: Fri Feb 26 2021