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Towage and Marine Operations

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  • ombugge
    replied
    Re: Towage and Marine Operations

    Originally posted by janihudi View Post
    so i reken that the price of a new anchor is so much higher, than the costs for try to pick up a lost one from the seabed?
    Yes Thijs, a 7.5 t. Stevpris is worth a lot more that it's scrap value.

    An anchor may not sound like a "high-tech" item, but a lot of experience and research has gone into the design of the Vryhof anchors.

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  • janihudi
    replied
    so i reken that the price of a new anchor is so much higher, than the costs for try to pick up a lost one from the seabed?

    Leave a comment:


  • ombugge
    replied
    Putting it to good use:




    Piggy backing:






    The Bridge during anchor handling:


    Not very practical lay-out of the Control Panels. The Ch. Engineer operating the winch is blocking the view for the Captain handling the boat. That is what you get when somebody with no practical experience gets to design the bridge.

    To make it worse they hired the smallest Indonesian Captain and the biggest Pinoy Chief they could find.
    Last edited by ombugge; October 25th, 2010, 12:10.

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  • ombugge
    replied
    In another thread there was a discussion about Grapplers and what they are for.
    Here is one being used to find and recover an anchor that had been missing on the seabed without anybody having recorded the exact position. All I knew was what the anchor had been used for.

    Using a Grappler tailing behind a boat and running lines diagonally across where logic told me the broken wire and chain was likely to be, we managed to get a grip on the chain and bring it on deck:


    The 7.5 m.t. Stevpris Anchor is on deck:


    Good as new after two years lost on the bottom:




    Two more missing anchors escaped "capture" and is still there, somewhere off Kelantan, Malaysia.
    Last edited by ombugge; October 25th, 2010, 12:12. Reason: replacing pics

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  • pilotdane
    replied
    Very interesting to watch the operation. Even though I've see photos of all sorts of mega operations I am still amazed when I see the people standing next to the lifting hook and piles. They look big but then when you see people next to them they become huge.

    Hearing you tell of weather windows. Missed that window, get back to a stable position and wait for another window. Is another side of the story that is not often said. I am accustomed to see such operations condensed to a one hour long TV show. It's interesting to hear more of the troubles and long delays waiting for the weather, though I'm sure you would call it something other than interesting when the jacket was dancing around trying to take the crane to the bottom.

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  • Seagull
    replied
    Just a quick post to say yes, it is of considerable interest –a riveting and satisfyingly detailed words and pictures account of the technical acomplishment and challenges involved in such an operation, and, it seems, intertwined with a very personal story. Greatly appreciated that you shared this.

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  • ombugge
    replied
    A great relief for everybody, but it was still left to secure the jacket with piles.
    The Barge HD 2007 alongside with the piles:


    First pile positioned for upending:


    Upending in progress:






    I only got to see the first pile set, as I was relieved at 1510 hrs. 30. March and left the HD 2500. That same day at 2210 hrs. I was admitted to hospital in Hong Kong.

    I long post, but I hope it is of interest to some here on CVF.

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  • ombugge
    replied
    The jacket was towed in circles around HD 2500 by the two Britoil tugs until 27. March.
    11 days with many of the rupture discs on the jacket blown and only the air valves holding the water to flood the legs. Not a very good situation to be in.
    It looked like another weather window, long enough to unend and set the jacket was in the offering, finally.

    On the 28. March at first daylight the jacket approached the stern. Waiting on confirmation that predicted lull was sufficient to accomplic the operation, incl. setting at leat two piles, before the weather deteriorated again. (We were now coming close to the end of the NE Monsoon season):


    The weather forecast for the next 48 hrs and outlook to 72 hrs. was within the criteria of 1.5 m. seas and it was approved to commence the upending operation.
    The jacket was brought into position again, upended:

    And set down on the prepared template. According to my log; 1220 hrs. Jacket on bottom. Slacked off on slings:


    And there it was, standing proudly by itself, the HZ -19 Jacket:

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  • ombugge
    replied
    The next day, as the weather had deteriorated further and the forcast was not good, it was decided to add more mooring lines and to de-ballast the legs.
    To do this meant sending people back on the jacket:

    Finally, with the jacket floating with one face in the surface, we could slack off on the hook to avoid any risk of shock loads:


    The situation remained the same until 16. march, when there was a short weather window. Not long enought to upend and set the jacket, but sufficient to get the jacket away from the HD 2500, before the weather deteriorated further.

    That ment disconnecting the slings and hoses, re-instate the bridle and let go the mooring lines:




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  • ombugge
    replied
    That is when the problems started. This jacket was not self- upending, (like shown in the links above) The next step was to blow the "rupture discs", which had been placed to avoid the legs of the jacket filling prematurely. This failed since the compressor to be used had been damaged in transport.

    After some inovative thinking we managed to blow 7 of the discs, but not the last 4.
    Meanwhile the weather deteriorated. It was necessary to get the jacket upended quickly by filling water "from the top" with hoses, which worked.

    By 0900 hrs. Saturday, 13 March the weather had deteriorated to where we could not be positioned over the Template on the bottom due to heave.
    The jacket was now upright and stable as long as it was kept at a certian depth. We secured the jacket to the stern of HD 2500 at a hook load of only 600 - 650 m.t or so to wait for another lull, which was expected within 18-24 hrs.

    But at 1225 hrs. the Crane operator descided to lower the jacket to get his people off, without telling anybody, which resulted in the jacket becoming unstable.
    I don't know if this comes out visible, but here is a short video of a 5000 m.t. jacket doing a bit of a dance at the stern of HD 2500:


    When the Crane Operator noticed tension increase to over 1,200 m.t. he left the crane and refused to go back up. Another Crane Operator evetually manage to lower the jacket to a stable position at around 650 m.t hook load.

    It was decides to lower the jacket back to afloat position, maintaining the slings attached, with t2 tugs holding the jacket in position, away from the HD 2500.:

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  • ombugge
    replied
    HZ Jacket Installation, China, March 2004

    As said in the above thread I have dug up some pictures from the installation of the HZ19-3 Jacket for Agip, off the Pearl River Delta, China, in March 2004.
    This operation very nearly went wrong. (It also almost cost me my life, but that is a different story)

    I got to Shekou 1. March, 2004 but did not get on board the Crane Barge as a tire exploded on the Helicopter on take-off. As it was still NE Monsoon season the weather was far from ideal, so no flights where possible the next day. I returned to Singapore on 4. March to await better weather forecast.

    I returned to Shekou 8. March and on board the Crane Barge HD 2500 the next day. (Sorry, no pics found)
    The Jacket had already arrived several days ago on board the Launch Barge HD 1006. We waited for a lull in the Monsoon for several more days.

    Finally on 11. March, 2004 we received a favourable forecast for 48 hrs. and I signed Certificate of Approval to commence launching off the barge. I could not find any pictures of the actual launching off the Transport Barge, but the process was much like what is shown in the links in the post above.

    The Jacket was launched at 1452 hrs. and was in position under the crane of HD 2500 at 1515 hrs., 12. March using 2 Britoil tugs:




    The jacket was secured at the stern of HD 2500:


    The slings hooked up:


    And a slight tension taken in the block at 1637 hrs.:

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  • ombugge
    replied
    Jacket Launching

    Time to revive this thread, which has been dormant for a long time.
    Inspecting the Launch Barge S-45 a few days ago gave me the idea to show you the process of launching Jackets from a barge offshore.

    Here is a couple of YouTube links.
    From the barge: http://www.youtube.com/watch?v=9ufBdAcgaMI

    And from another angle: http://www.youtube.com/watch?v=EewtD...x=3&feature=BF

    The whole platform assembly process, from loading to installation in the field: http://www.youtube.com/watch?v=o79gb...x=4&feature=BF

    I had nothing to do with this project. The above was taken from You Tube.
    This project was performed by Heerema, using the SSCV Thialf, which has been featured several times in another thread on CVF.

    I will see if I have some pictures from a project in China I was involved with, which nearly went wrong. If so I will post them here soon.

    Pics from the Launch Barge S 45 will be posted in an appropriate thread.

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  • ombugge
    replied
    Float-over Operations

    Not to let this thread just fade away on page two, here is a couple of float-over operations done in this region.

    First at Malampaya Field, offshore Palawan Island, the Philippines:


    Second one offshore West Malaysia/Thailand:

    Pics from the web courtesy of KRB and Dockwise

    A simple way of transporting and setting an entire Topside packet, or just a deck structure, onto a jacket at sea. No need for expensive Crane Vessels.

    No, I was not involved with any of these two operations, but I have done a similar operation in the Mahakam Delta, some 10 years ago. Not as heavy as this (abt. 4,500 m.t) but complicated because it was way up a relatively narrow river, with strong current and very limited water depth.

    As said earlier, same principle can be used for installation of low bridge spans.
    For higher bridges, lifting with SSCV or Crane Barge may be required. (See Janihudin's post in the Crane ship thread)

    Float-over was used to install the new "Stromsbrua" in Skodje some years back, but I haven't been able to find any pics from that operation.
    (The completed bridge was featured in another thread in this forum some time back)

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  • ombugge
    replied
    Cross-discipline thinking

    This pics is from another thread:
    Originally posted by Mr. Photoman View Post
    This is where cross-discipline thinking and knowledge comes in. That trick bit could be constructed on dry land anywhere, loaded and transported to the bridge site and set in place by HLC or Transport Barge(s), using the Float-over method.

    Or using a combination of the above and an Offshore Crane Vessel for the final installation. Piece of cake.

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  • Guest's Avatar
    Guest replied
    Informative and educational...

    My sincere thanks to contributor Ombugge...very surprised such colossal activities going on at the surfaces (and depths) of the seas...

    We don't usually get to see this on tv....

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