5.6 ANCHORING AND LIGHTERING; MOORING AT SPM'S
When the discharge berth is occupied, or the vessel's draft is too
deep to berth on arrival, the tanker will go to anchor and await berth
availability or lighter to docking draft.
5.6.1 Anchoring Prevailing or tidal currents.
The selected anchorage should be carefully reviewed for the presence
Exposure to severe weather.
Available water depth.
Submarine pipelines, cables.
Charted anchorage restrictions.
All advice received from local authorities should be viewed with suspicion,
the master being guided primarily by the actual conditions observed,
indications of the admiralty/coast pilot, the sailing directions and
navigation chart information. If the observed water depths are less
than those indicated by local pilots, receivers, or facility operators,
then the master has the right and obligation to abort the mooring operation
and request that supplementary soundings be made to verify the adequate
The anchorage must provide sufficient depth under the keel for all stages
of the tide and anticipated vessel trim. Sufficient clearance must be
available for the ship to passover its own anchors safely. If significant
tidal currents will be experienced, an allowance for the squat of the
ship at maximum current must be included. The anchorage must provide
sufficient room for the ship to swing clear of all shoals, obstructions
and other vessels. Anchors should be equipped with a marker buoy, especially
where there is a record of anchors being lost.
Despite having a pilot embarked, the master and watch officers must
regularly fix the position of the ship while approaching the anchorage
and verify that the ship is making the agreed courses to the anchorage.
The speed over the ground and depth of water under the keel should be
frequently verified and the depth alarm used, (if fitted).
The chief officer normally handles the anchor, ensuring well before
hand that all the anchoring equipment is available and the windlass
is in all respects ready for use. Preparations must always be supervised
by a deck officer and only experienced crew members should handle the
anchor machinery. Protective goggles and helmets must be worn by the
men operating the windlass brake. The anchor pawl or stopper should
be in place until immediately before the anchor is lowered.
To ensure the minimum opportunity for accident or damage when anchoring,
the ship should be fitted with a doppler speed log, with the transducer
mounted under the forepeak. The speed log should have a 'ground lock'
capability which will indicate the speed of the ship over the bottom
(rather than the speed through the water).
The anchor should be backed out (not dropped). When the master and chief
officer are in agreement that the vessel is at or near zero speed over
the bottom the anchor should be landed on the bottom and chain backed
out to the desired scope. The chief officer must keep the master regularly
advised of the length (scope), of chain out and the direction the chain
is tending. On smaller vessels, the anchor may be walked out to one
half of the water depth and then dropped. On larger tankers and in any
depth of water over 40 meters, the anchor should be walked out under
power to the desired scope. See the OCIMF publication Anchoring
systems and procedures for large tankers for additional guidance.
Anchor bearings should be carefully taken and verified before the anchoring
party is released from their duties. The doppler speed log set on ground
lock provides a second indication that the vessel is not dragging. Anchor
signals should be properly displayed.
5.6.2 Anchor watch
An anchor watch must be set with clear instructions to use all available
means to verify that the vessel is not dragging its anchor. Enter
anchor bearings in the log and plot the anchored position on the chart.
Plot a 'bridge turning circle' using the scope of chain and the ship's
length. Use cross bearings to regularly verify that the bridge is remaining
within the circle drawn on the chart.
The ship should remain at least 0.8 miles clear of all obstructions.
Engines should be maintained ready for manoeuvring if necessary and
the watch officer clearly instructed that he is required to use the
engines if necessary to avoid danger to the vessel.
The anchor watch must keep a vigilant, all around lookout. Approaching
vessels should be tracked by radar and visual bearings as if own vessel
were under way. The master must be called if it appears that a closing
ship will not pass clear and the watch officer should attempt to make
early radio or visual contact with closing vessels with small CPA's,
to determine their intentions.
If the vessel yaws excessively in river or narrow channel, it is sometimes
possible to minimise or eliminate the motion by use of the automatic
steering. Alternatively, if sufficient water depth permits, a second
anchor may be lowered on a short scope to reduce the motions of the
bow due to wind or sea.
The required anchor signals must be displayed and if the weather closes
in, the required sound signals made. The stage of the tide and current
should be closely observed. The master must be notified if there is
a significant change in the weather.
The deck watch should be assigned to make frequent rounds of the ship
and accommodation and the result entered in the log. Pilot ladders and
gangway must be raised to deck level except when in use. The deck watch
must keep a good watch for strange boats approaching and unauthorised
persons attempting to board the ship.
While at anchor in Angola, Brazil, Malaysia, the South China Sea, or
Singapore, special precautions are needed to prevent pirates from boarding
the ship. The master must seek recommendations from owners and the P&I
Club when en route to those areas. Further guidance is available
from the International Shipping Federation publication, Pirates
and armed robberies - A master's guide.
Tankers should not anchor in ice unless there is no alternative.
5.6.3 Lightering by barge
Most lightering operations are conducted in fairly sheltered waters
by barge. The barges are manned by experienced crews and are rigged
for going alongside, with all the necessary transfer equipment. Nevertheless,
a large measure of the responsibility for a safe lightering operation
rests with the crew of the tanker.
The operation should be conducted according to a written procedure prepared
by the chief officer and approved by the master. All applicable recommendations
of the OCIMF Ship-to-ship transfer guide (petroleum) should
be complied with and the publication (only 18 pages in length), should
be read by the chief officer and cargo officers prior to each lightering
operation. The OCIMF guide includes a series of checklists which should
be used for the lightering operation.
When the barge arrives alongside, it is the responsibility of the chief
officer to determine if it will be accepted for the lightering operation.
The fendering, mooring wires, winches and the transfer hoses should
be carefully examined. If any of those items or any other equipment
appears to be neglected, or otherwise present a safety hazard, then
the barge should be refused and turned away from the ship.
If the barge is accepted and no independent petroleum inspector is available,
then the chief officer must inspect the barge's tanks and piping system
to determine that the vessel is suitable to receive the ship's cargo.
If the barge is found unsuitable for any reason, it should be instructed
to depart and the owners and charterer's notified. At the end of the
lightering operation, the chief officer must again attend the barge
(absent any petroleum inspector attendance), to observes the gauging
of barge tanks and witness the barge report.
The quantity to lighter will have been calculated and agreed prior to
the vessel's arrival. If sea conditions in harbour permit and if a shore
boat or the barge tug is available, then the chief officer may be able
to visually check the draft of his ship near the end of the lightering.
Otherwise, the lightering will be completed by calculated ullages, with
the hope that they are correct.
5.6.4 Mooring at SPMsA means of securing the chafe chain. This would be a bow chain stopper
or an acceptable SMIT type towing bracket.
The vessel may be required to discharge at a single point mooring (SPM).
If that is the case, the vessel's mooring wires and ropes will not be
used. In most cases, the operators of the SPM facility will use their
own equipment and mooring crew to connect the mooring.
Before proceeding to the SPM, the charterers and operators should be
fully aware of the vessel's suitability to secure and discharge at the
The ship owner's responsibility is to provide:
Bow fairleads of the correct shape and size to pass the chafe chain.
Pedestal roller fairleads and winch drums/capstans correctly positioned
to provide the proper leads and clearances for the messenger lines.
Further details of procedures to be used at SPM moorings may be obtained
in the OCIMF publication Recommendations for equipment employed
in the mooring of ships at single point moorings.