Bourbon Dolphin capsizes

Discussion in 'Stability' started by Crag Cay, Apr 12, 2007.

  1. lazeyjack

    lazeyjack Guest

    No Troy, they stopped after she heeled beyond coming back and it was all over
    Nothing to do with it but how are the thrusters powered? mechanical link of hydraulics, thrusters were well after my time.
     
  2. rayk
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    rayk Senior Member

    Port ballast I think.
     
  3. Johannpeter
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    Johannpeter Visitor

    Divers risk lives to find tug crew
    20.04.07 15:26

    NAVAL divers tried in vain to rescue the crew of the oil rig support tug Bourbon Dolphin which capsized off the Shetland Islands.

    A four-strong team from Northern Diving Group battled horrendous conditions to try to get inside the upturned hull of the vessel, which capsized while working with the rig Transocean Rather.

    Five crew from the support ship were still unaccounted for as the NDG team arrived from Faslane, via RAF Lossiemouth.

    They had barely arrived back at HM Naval Base Clyde from a call-out dealing with suspected unexploded ordnance when the SOS came from the rig in the Rosebank oil field, roughly 75 miles west of the Shetlands.

    At first the divers tried to manoeuvre a robot submarine inside the stricken vessel.

    Currents and Atlantic swell made it impossible for the submarine to enter, so it was left to the NDG divers – WO Steve Strange, CPO Willie Sharp, LD ‘Faz’ Farrell and D1 John Anderson – to do it manually.

    With the hull moving violently up and down in the heavy swell, there was a great danger of the frogmen being sucked into the ship.

    They managed to get inside the Bourbon Dolphin’s bridge – where there was no sign of the missing crew – but after three dives, the team decided it was too dangerous to continue.

    “This was not a run-of-the-mill job – this was extreme diving. My team did a bloody amazing job,” said Lt Cdr Andy ‘Sharkey’ Ward, NDG’s Commanding Officer.

    “Swell makes things tricky and the currents were intense. You’ve got an upturned hull, water being sucked in and out, doors opening and closing.”

    All the time there was the threat of the tug sinking, taking any divers down with her to the bed of the ocean, one thousand metres below.

    “There was still some hope that there might be someone alive in an air pocket – if it had not been a question of saving lives, then my team would not have gone in,” Lt Cdr Ward added.

    “In the end, they realised that it was far too difficult.”

    Five people died in the tragedy, including the son of the tug’s skipper, who was on work experience with the vessel. Four days after capsizing, Bourbon Dolphin defeated salvage efforts and sank.

    http://www.navynews.co.uk/articles/2007/0704/0007042001.asp
     
  4. lazeyjack

    lazeyjack Guest

    what can one say, never realised she was so deep
     
  5. acearch72
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    acearch72 Junior Member

    On the dropping of the pin, it is possible in this situation they were concerned about the aft deck submerging, at which time they would lose waterplane hence stability. It may have been deemed better to let the chain slide to the cable stops (staghorn) which will be much furhter forward than the pins. The over the side pull would be in a more bouyant portion of the vessel, and it could have been thougth that transverse stability would be better able to resist the overturning moment with the aft deck not submerged. This would have been a guess because they certainly did not have time to run a stability analysis.
     
  6. smartbight
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    smartbight Naval Architect

    More Details

    27 April 2007
    Rolls Royce denies problems with emergency release




    THE HEARING also heard that the emergency release on the Bourbon Dolphin did not work.

    During the dramatic seconds the first mate Geir Syversen pushed the button that should release the chain, but it failed to work.

    "I experienced that the ship listed so much that I shouted to the captain. Now I leave, and then I was half-way. The captain asked me to push the emergency release button. I had understood that then all the chain should rush out in great speed and sink to the bottom," Mr Syversen said during the inquiry.

    He pushed the button and stood next to his chair but couldn't see that anything had happened, apart from the instrument showing that the chain went out with only 12m per second. "This I saw before I started to climb up towards the starboard side of the wheelhouse. There were six people on the bridge at this moment in time," said Mr Syversen.

    Himself, the chief mate and an able-bodied seaman were nearest the door on the starboard side. They had great problems in opening it because the ship was listing so much and the door opened outwards.

    Mr Syversen saw the captain (Oddne Arve Remøy), his son (14-year-old David Remøy) and an able bodied seaman falling down towards port side. He escaped out of the wheelhouse and found himself there together with the chief mate. Mr Syversen started to climb on the starboard side. At that moment the vessel capsized.

    "I fell down and went under the water, but came quite quickly to the surface. I saw the vessel just half a metre away from me. I did not have time to get on any lifesaving equipment, but saw an able bodied seaman with a lifebelt on in the sea and swam towards him. A liferaft was drifting towards the two of us and we got into it. For some reason or other I looked at my watch just then and the time was 17:05 local time," Mr Syversen said.

    "After some minutes an able bodied seaman came swimming towards us and we pulled him onboard. Later, after 30-35 minutes in the raft we were fetched and brought onboard the Viking Victory."

    This was the first trip Mr Syversen had onboard Bourbon Dolphin, but he didn't think that posed any problem as he was well acquainted with the boat and the equipment on the way from Lerwick towards the position of the rig and equipment was similar to what he had experienced on another boat before.

    A government inspector wanted to know what effect it had that the Highland Valour had pulled in the wrong direction for about 30 seconds when it was helping with the chain. Mr Syversen's opinion was that it had caused the sea to break over the side of the boat and that the boat had significant lists.

    Later when the inner starboard towing pin was lowered and the chain slipped over to port side he observed that the list gradually became worse. Afterwards he had been thinking that the purpose of changing positions of the towing pins could have been that the chain should have more room to move.

    Mr Syversen could not say if the release button for the chains had been tested * if so it had not happened when he had been on duty and he had not read about it on the journal of the ship.

    When questioned Mr Syversen said that the greatest load that they had had on the winch, which has a pulling power of 400 tonnes, was 330 tonnes.

    Afteward the hearing director of information Mr Arnfinn Ingjerd at Rolls Royce maintained that the Quick Release system on the winch of Bourbon Dolphin worked as it should.

    He said: "Under optimal conditions this system shall free the chain from the boat. I interpret the explanation by the first mate such that the system worked when he activated it.

    "It has to do with the position that the boat was in when the system was activated. In normal position this would have happened significantly quicker, but there are limits to how quickly one can let out chain," he said.

    Asked what did he think was the reason it went so slow when the system was activated on Bourbon Dolphin, he said: "That I will not speculate on but I said from what has been said it looks as though the system has worked."
     
  7. Guillermo
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    Guillermo Ingeniero Naval

    If the vessel was heavily listed to port while still having the pull from the stern (cable between the pins), it can only mean the cable was already openly calling with a big transversal component to port (big angle), probably because of the vessel trying hard to head a rhumb as to avoid going over anchor number 3. Lowering the towing pins to allow the chain bring the pull to a more forward position (staghorn) could only make for a lost of control of the free rear part of the cable over the deck, allowing it to slip suddenly over the side, as it seems it did, not solving the problem, in my opinion, but worsening it (they had recorded a 330 tons tension) in spite of the rising of the stern deck over sea level and consequent increase in stability. I'm still confused about this manoeuvre. But it's easy to speculate from my chair. One have to be there.

    Maybe the cable jammed somehow at the staghorn because of the big angle of the cable calling from the side, and this hindered the freeing of it when the emergency button was activated...?
     
  8. charmc
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    charmc Senior Member

    I recall earlier reports describing the chain leading around the starboard towing pins at an extreme angle off to port. The pressure that created was why they could not lower the starboard pin at first, and why they were listing to port.
     
  9. charmc
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    charmc Senior Member

    Johannpeter, thank you for posting the report of the divers. From their description of the capsized vessel, just below the surface, rising and falling in the seas .... they were heroic to enter at all. Those conditions are a deathtrap. I have dived on wrecks in the North Atlantic. Cold water, so lots of gear to snag. Entering is always a thing of danger even when the wreck has been on the bottom for years. In a slight current, corroded plates, hatches, and fittings can move and trap a diver. In those conditions, with the overturned hull rising and falling 2-4 meters rapidly.... those divers are heroes to have attempted the rescue at all.
     
  10. smartbight
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    smartbight Naval Architect

    Attached info on B.D.
    1_Ulstein specs on BD
    2_Bourbon specs on BD
    3_Ulstein specs on A102 < on their pamphlet they have moved the staghorn (towing cable stop) further aft.

    Trying to check all info from sometime conflicting journalists' reports:

    The specs do list 2 sets of towing pins P/S (about 8' between P & S outer pins) as shown on Ulstein illustration. The staghorns P/S are shown on all pictures of the B.D.

    From those reports; I get the following picture:

    The B.D. has paid out 1800 m of chain that had been stored on a drum or drums of the A.H. winch?. The B.D.is trying to pay out the last 300m of that anchor chain still spooled on the drum. The chain storage compartments and windlass are not used on this phase of the job.
    The chain rode hanging from the boat is connected to a cable and through a swivel to one of the mooring winch on the rig and form a catenary touching or not the ocean bottom.

    Can you confirm ?
     

    Attached Files:

  11. charmc
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    charmc Senior Member

    I believe the anchor chain would have been paid out from the rig winch, with BD secured to the anchor by her own chain or cable. Either way, because the bottom was so deep, that load was made of the anchor, 1800 m anchor chain, and 900-1000 m tug chain or cable. The forces are as you describe. The load was not touching the bottom, rather the entire load was on BD, which was originally planned to only assist, not carry the entire load. Highland Valour attempted to assist but was inable to hook and secure (not surprising, IMHO, given the conditions and depth.
     
  12. rayk
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    rayk Senior Member

    pins

    charmc, I found some photos of pins.
    (They arent big, so click on them and magnify for a good view.)

    The BD had started moving ballast from port to starboard during a port list with almost 300t through the starboard pins.
    (The bottom left thumbnail shows how BD pins were set to start with.)

    To lower the inner starboard pin, BD was steered a little to starboard. When the pin dropped, the chain moved to port.

    The BD wasnt in trouble with 300t to starboard, but when the load moved to port, the boat capsized.
    It is only a couple of meters, but that is all it would take.

    I hypothesize that the boat wasnt able to coordinate the transfer of ballast and load at the same time.
     

    Attached Files:

    Last edited: May 3, 2007
  13. charmc
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    charmc Senior Member

    Thanks for the pins photos, rayk.

    I believe both played a role. I think she was listing to port because of the extreme angle I spoke of, pulling around the starboard pin and off to port. I think you're right, the list was a dangerous condition, but not enough to create an immediate danger of sinking or capsize. Shifting ballast to starboard would help offset. Once the pin was lowered, though, the line whipped rapidly around to port even more, sliding up the bulwarks until even with the staghorn. Had they been able to shift enough ballast to starboard in time, perhaps that would have given her enough stability to hold on for a few minutes, maybe they could have brought her head up enough to shift the load back toward the stern....
     
  14. StianM
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    StianM Senior Member

    Normaly this ships have 4 thrusters or 5 in some cases.

    All thrusters on this ships are electrical 380-690v.
    Normaly they have one stern thruster and one bow thruster supplied from 1 shaft generator and the other stern and bow thruster suported from the other one.

    Shaft generators are fitted on the reduction gears where the engine/engines go in and the proppeler shaft go out.

    1100meters.

    I think Eide Marine Services has ben involved in a posible salvage operation.
    So they really was using rolls royce ulstein winches? I thought those day was ower after I read they had a co-operation with developing safer systems toghether with odim.
     

  15. Guillermo
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    Guillermo Ingeniero Naval

    Some interesting photos from http://www.menkent.dk/ , three showing the maneouvre with a rig's anchor and one of a J hook.
    Pins and shark jaws at work are clearly seen, as in Rayk's images.
    BD was not performing this maneouvre, as I see it, but rather the one suggested by Charlie: "I believe the anchor chain would have been paid out from the rig winch, with BD secured to the anchor by her own chain or cable. Either way, because the bottom was so deep, that load was made of the anchor, 1800 m anchor chain, and 900-1000 m tug chain or cable."
    I think the shark jaws were not at work and the line running between the pins was cable and not chain. As I see it there was no anchor on deck (except if it were an spare one, which I doubt), contradicting one of the first statements in the news (press) on all this.
     

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