Bourbon Dolphin capsizes

A couple of additional images from the same site, showing the main winch and the fairlead with its supporting structure.

 

Found in a blogspot:
(http://www.ruttledge.se/2007/04/26/bourbon-dolphin-court-hearing/)

"As a current crew member of the Highland Valour and eyewitness I am not currently allowed to comment on any events concerning the Bourbon Dolphin capsize, but would like to remind people not to speculate based on the frequently innacurate reporting from the media who quite frankly would not recognize an anchor if it fell on them. The official enquiry will reveal the whole story in time. Until then I suggest any media reports are taken with the large pinch of salt they usually deserve."

 

A couple of very short videos:
http://www.youtube.com/watch?v=1N6u6P0e-dY&mode=related&search=
http://www.avdp-arma.com/html/maritime___shipping__safety__t.html

 

Bourbon Dolphin salvage 'unlikely'


By Upstream staff

Photo by AP


Maritime insurer Gard, which insured Bourbon Offshore Norway's anchor handling tug supply (AHTS) vessel Bourbon Dolphin, said it would not fund any attempt to raise the vessel, saying it was "very unlikely" that salvaging the ship was possible.

The AHTS capsized while working at the Rosebank field, 157 kilometres north-west of Shetland, on 12 April. Three of the 15-strong crew on board the vessel died, while five are missing, presumed drowned. The AHTS sank in water depths of about 1100 metres on 15 April.

"Gard will not cover the costs of raising the Bourbon Dolphin, even if it were technically possible," it said in a statement released today.

However, Gard said it had called in London Offshore Consultants (LOC) to advise it on the possibility of raising the Bourbon Dolphin.

LOC told Gard it was "extremely uncertain" whether it was technically possible to raise the ship, noting that the greatest depth from which any ship had previously been raised was about 600 metres. The report added that the vessel in question was much smaller and lighter than the Bourbon Dolphin.

The report said a salvage bid would be risky for a number of reasons, not least that the AHTS sank in a location prone to extreme weather, with difficult wind, wave and current conditions. The enormous water pressure at 1100 metres adds to the risks of a salvage bid.

The consultancy's report added that "any method that could be attempted would be untried and would require a significant period of time for research, engineering and planning".
30 April 2007 17:07 GMT | last updated: 30 April 2007 17:07 GMT

http://www.upstreamonline.com/live/article132421.ece

 

BD was about 2500t, and ballast tankage was about 2000t. That is a lot.

For example try doing the same thing with an eighty pound anchor in a six foot pram dinghy. Slide the rhode from one side of the transom to the other, while sliding your body weight across the thwart. If the rhode slides across the transom faster than you can compensate, it will all be over in a flash.

I am neither a maths man , nor a navel architect, but my understanding is that there is no direst corralation size wise Stabilty does not foolow size but is rather like this A force 4 quake is not half as strong as a force 8 quake, it is far less than 5o% A 200 foot ship is nowhere near 50% as stable--if that is the word than a 400 foot ship
Perhaps a few can elaberate for me

 

jack,
for the same righting arms, righting moments are in direct relation with displacement (RM = D x RA), so a vessel displacing twice as much as a lighter one and having the same righting arms curve, resists twice the heeling moments. This doesn't mean a ship twice the length than another one has twice the stability. As said, for equal RA curves, the RMs are related to weight, not size. Anyhow, as bigger vessels are also usually heavier, colloquially we tend to talk about size instead of displacement.

About BD's ballast issue, I haven't heard the port tanks were filled during manoeuvres. Only the starboard ones are mentioned. Neither emptying port tanks or transfering ballast water form port to starboard has been mentioned.

 

Thanks mate I did not really mean LOA ,
Salvage, what would be the weight on a line, to lift her off the bottom?
do you think, they could skid her into shallow water?
just musing here, dunno the lat long , bottom,

 

well i did mean loa but was vague, jus wanted the relativaty disp, tonne per tonne Righting arm

 

You were rigth, Jack. They pumped from port to starboard. Thanks, Rayk.

 

Since some of us are employed in this industry we cannot wait 6 months to a year for the 'final' report. I earned my college money working in the engine room and I hope we can design a boat which gives the Engineer/Electrician below more than a minute warning before the floor plates fall on their faces.
So far we have the most intelligent forum going. I looked at SNAME & RINA, nothing! Luckily there are enough survivors & witnesses; We will learn what happened!. This accident is as shocking as the 'Vasa' ? must have been 400 years ago.

Thanks for posting the pictures of the towing pins.
I am sure ballasting P<>S while doing A.H. is not in the Ulstein Trim & Stability booklet; Too dangerous !

 

Searching for more info, I've found the Olympic Octopus, with some innovative features, among them the rim driven thrusters. Brian Eiland will like this.
http://www.olympic.no/download.asp?object_id=3E57A6AD17334A30A4C33D2A514C800E.pdf

 

sorry abt my post abt towing her to shallow water, i did not know she was so deep thought was 1000 feet not metre
Unlike the Kursk, which they had to raise to find out what went wrong, BD maybe in her grave and the men with her Anyone have the co ordinates where she went down , would give me an idea of that part of the world. thanks

 

Jack,

I make that mistake all the time. I did it visualizing the chain load on Bourbon Dolphin. I was thinking 1800 ft was a lot of chain, very heavy load ... then it hit me that the load was more than 3 times that, over a mile of chain.

According to a report from Smit Salvage, she sank at 61º 03.53N 003º 48.92 W.

 

I think CharmC is on to something as shown on RayK's picture below.

Once the pin was lowered, the line whipped rapidly (330 T tension) around to port even more, sliding up the whaleback. The BD heel increased 10 > 20 > 45 deg. Around 45 deg flooding through the E.R. ventilation air inlets started. Around 50 deg > chain jumped the bit and stopped at the staghorn.
The attempt at ballasting could not succeed (too slow).
The port bit looks quiet beefy and was not damaged or uprooted by the shock load ?

 

Sad...

So she DID have an anchor onboard, and it was positioned to Port... Maybe one more factor...