410-Mooring Operations / 748
Moorin
g Op
erations
BOS-PRD-07.900607
One buoy per line is required unless lightening buoys (spring buoys) are used to avoid line contact with
obstruction on the bottom. Piggyback anchors may be used depending on the bottom type or to increase the
load admittance on anchors. Chain can also be provided, to be installed between anchors and wire cable to
increase the holding on seabed.
On the SMV, no specific mobilisation required, unless the subsequent operation itself requires extra
equipment.
Arrived on the field, if
S
ite Mana
g
er
authorises the operation and if weather conditions are within the agreed
limits, the anchor deployment may start.
The AH vessel usually has the positioning system on board to know where to drop the anchors and where
are the obstructions.
The SMV will hold a constant position as far as practicable at the safety position while the AH vessel deploys
the anchor lines.
Once all anchors have been deployed and all pig tail’s marking buoys are plotted on the radar, a tension test
of 30 minutes minimum will be done to confirm the proper setting of anchors, according to international rules
chapter 10.4.6.3 of ISO 19901-7-2005
. Alternatively, upon charterer procedure, it’s usually agreed that three
times the anchor weight
should
be applied on each line. During tension test the AH Vessel will make a round
trip to check that there is no change of position on pig tail’s marking buoys.
If the test is passed, then the SMV may stop her engines and move to working position heaving and slacking
on her lines. The lines will be used to change position for the rest of the operation, unless weather imposes
to start engine as back-up. Propulsion
shall
also be kept running if the ship is to approach very close to the
structure provided that no divers are in the water.
Pig Tail
Obstruction
Piggy Back
Anchor
Version 04. Original date: 22/06/2012. Version date: 31/12/2014. Valid version only on QMS site. Uncontrolled document when printed.
Procedure prepared by: BOS Operations Department Project Coordinator. Approved by: Head of Operations. Validated by: BOS Quality Representative
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