Stocks that Float: TANKERS & DRY BULK SHIPPERS

[xanadu90]

DOCK Here's a good description how the heavylift work is done:

March 13, 2008

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Maari Project halfway there!
On March 7th 2008 an important milestone in the Maari Project has been achieved
when the load out of the wellhead platform was succesfully executed on the Blue
Marlin at the Kencana Yard in Lumut- halfway in the Mallacca Strait on the west
coast of Malaysia.
Dockwise management appointed this contract as a project in October 2006,
because of the extended scope of this contract and the high risks involved in the
tranport. The transport: Singapore: bunkering, Batam Indonesia: preparation works
and installation of grillage, Lumut Malaysia: load out, Admiralty Bay - Northern part
of South Island New Zealand: float off.
The extended scope were to be a new experience for Dockwise, when we took on
the responsibility of the design of the grillage, skidbeams and seafastening. This
meant a real challenge for our structural engineers, because the forces – generated
in the 150 metres high and over 10.000 ton weighing platform tower – will come
into the vessel’s deck almost only through the four tower legs: In the harsh
environmental conditions of the Tasman Sea that could cause over 10.000 tons per
square meter pressure into the deck! Truly state of the art engineering realized a
grillage that could cope with such forces.
The risks that were to be conquered and controlled are:
The location of the fabrication yard, which is situated in a shallow creek, that does
not exist on a nautical chart. The largest heavy lift vessel in the world had to go in
there and come stern to for the load out quay. Detailed dredging specifications were
supplied by the project team, and a mooring procedure was issued and approved by
all authorities involved.
Once moored stern to, the vessel had to be able to cope with a tidal rise and fall of
the water of over 70 cm per hour, whilst the platform was hydraulically pushed -
skidded out –from the quayside on the vessel at a planned 5 metre per hour rate.
An extra external ballastsystem was engineered and installed without endangering
the projects critical path.
For the transport the main challenge for the team was to come up with sufficient
seafastening, that would not damage the weak construction of the bottom part of –
the so called skirt – of the platform, that was not designed for this at all. It was
done at the cost of time of a planned twelve days of welding work.
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The challenge at the float off will be the fact, that the skirt of the platform is hollow
and therefore will not float. The complete contruction will only start to float on the
platform above the skirt. This means that the Blue Marlin must submerge without
having the needed stability of the platform. However, the skirt catches airbubbles
when it submerges and with the help of a barge, loaded on the forward part on deck
of the Blue Marlin, it will be possible to have enough stability during submerging of
the vessel and reach sufficient clearance between vessel and platform to float it off.
The ballasting procedure for submerging has been thorougly prepared,
incorperating the control of eight airbubbles under the skirt!
Impressions of the load out:
March 4th 2008:
Off the chart, into the creek, 1.3 meter underkeel clearance.
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Anchoring in the mangroves.
March 5th 2008:
View of external ballasting system and stability barge, Dockwise scope of work.
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March 6th 2008:
First skidshoe on board, 523 millimeter spare between casing and platform. Good
view of Dockwise designed skidbeam, grillage and seafastening arrangement.
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March 7th 2008
Loaded!
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Time proven reliable skidding method used by the combined project teams !!


http://www.dockwise.com/files/images/080311_Maari__Project_almost_halfway_there.pdf