MARITIME

CASE STUDY: HEAVY LIFTING
Load ...
... & Float away.
“A few hours before we had the right water depth, we
ballasted the vessel (Dockwise Vanguard) so it had a
free board of 1m,” says Terpstra. “We then waited for
the final go-ahead.” With the go-ahead given, the team
continued to ballast the Dockwise Vanguard while the
four harbor tugs brought the FPSO to its stern. At 4:30
pm, the float-on operation started, with the first tugger
lines (from the Dockwise Vanguard to the Armada Intrepid)
slowly pulling the vessel in between the two aft
casings. It’s a slow and careful process, with the Dockwise
Vanguard crew taking over the handling for the final
positioning on to guide posts on the heavy transport
vessel’s deck.
By 7:30 pm, she was in place. However, even once in
place, the position had to be monitored, to make sure it
was correct, before the Dockwise Vanguard was slowly
de-ballasted, finally lifting the Armada Intrepid out of
the water. Once the Armada Intrepid was fully out of the
water, further inspections were carried out and, finally,
deballasting was completed and the load successfully
executed. The final task, before sailing, saw some 54
sea fastenings (each comprising approximately 2.5 x
3m brackets) welded into place, to make sure the FPSO
would remain secure during the transit, about 54 sea
fastenings. “The operation was executed under ideal
circumstances,” says Terpstra. “The weather was perfect,
no wind and clear skies, resulting in good sight,
which is essential for the operation. Altogether, the operation
went well, as per schedule, and no unforeseen
circumstances were experienced.”
Preparation
However, loading an FPSO, or any major load, onto
the Dockwise Vanguard’s deck requires more than just
careful loading and sea fastening – a lot of preparation
work is required, making the fast turnaround all the
more remarkable. First, the Dockwise Vanguard had to
be cleaned following its transport of the Goliat FPSO.
Then, the vessel had to be fitted with cribbing material
- a 600mm-high wooden layer fixed with angle bars
bolted to the deck, on which the Armada Intrepid or
any other load would rest. In addition, the guide posts,
against which the FPSO is positioned, had to be installed.
All of this was done before May 8.
Further, the work will not stop until the FPSO is safely
delivered, even though it has been safely loaded and secured.
During the voyage, the FPSO, sea fastenings and
cribbing are being regularly inspected.
For this transport, Dockwise is also trying something
new - having permanent, real-time pressure monitoring
on the cribbing. “This is something that has not been
doing before and we are trying it,” says Terpstra. “So
far we have not been able to this. We will be able to get
real time data on this voyage.” All in all, it’s a big job.
The Dockwise Vanguard’s crew was increased for the
loading operation, from the usual 25/26 to 33, because
of the amount of line handling involved, says Terpstra.
With Dockwise as the main contractor, the project also
used other Boskalis Group companies, including using
SMIT Harbour Towage Northwest Europe tugs.
For Hans Leerdam, the biggest achievement is proving
the FPSO transport concept. “For me, this is an innovation,
a first,” he says. “We are able to show to the
market this is a better, faster, more efficient solution to
transport ship-shaped FPSOs from one side of the world
to another, be it for refitting or new builds. The alternative
is a wet tow - at half the speed. We expect the Dockwise
Vanguard to cruise up to 12,5 knots. Wet tow speed
is about 6-8 knots. You can also be more flexible, going
around bad weather. You are safer and more in control.”
In fact, insurance premiums for wet tows are 10 times
more expensive than the dry tow alternative, showing
that insurance companies recognize that dry transport
is a safer solution, says Leerdam. The Dockwise Vanguard,
with the Armada Intrepid on board arrived in
South East Asia, early July, sailed via the Cape of Good
Hope, without the need for tugs and in less time than a
wet tow would have taken.
60 Maritime Reporter & Engineering News • SEPTEMBER 2015