2.3 PREPARING FOR HEAVY WEATHER BALLAST - TAKING DIRTY
Ballast quantities as low as 25% of the ship's deadweight may be sufficient
for un-docking operations in most ports. Ballasting will continue as
the ship departs the unloading port until all the ballast required by
the departure ballast plan is on board. In most cases, the draft and
trim produced by the SBT or CBT capacity of the ship is sufficient to
manoeuvre in port and proceed en route to the next loading port without
undue fuel consumption or damage to the vessel. Additional ballast may
be taken into the ship's cargo tanks if the master thinks it is necessary
for the safety of the ship. This does not mean that the master can ballast
dirty cargo tanks to maintain desired speed in adverse weather. The
most effective ways to reduce damage in heavy weather are to reduce
speed or alter course. Only when these measures have been taken may
additional ballast be loaded in the cargo tanks to ensure the safety
of the ship.
When it is probable that additional ballast will be needed during the
voyage, the appropriate tanks will be required to have been crude oil
washed. Ballast water that has been put into a tank that has been crude
oil washed, but not water rinsed, shall be regarded as 'dirty ballast'
and handled accordingly. This may mean discharging ballast ashore at
the end of voyages made entirely within a prohibited zone.
Ballast water shall not be put into tanks that have not been crude oil
2.3.1 Preparing additional tanks for heavy
The following typical procedure refers to the IMO example vessel, cargo
and ballast systems used to illustrate the CBT operations in section
2.2. While filling the CBT tanks, flush the selected
tanks suction piping with clean ballast water and flood the tank bottoms
until covered. The following steps are required:
- While ballasting No.2 centre and No.4 centre CBT tanks, open valves:
47 (No.3 centre cargo tank suction and fill valve). 24 (No.1 centre
cargo tank suction and fill valve).
- Fill each tank to a sufficient innage to cover the entire tank bottom
at the existing trim.
- Close valves 47 and 24.
- When CBT tanks are full, close all valves.
- At sea, check the available capacity in the starboard slop tank.
Decant slops and/or transfer from starboard slop tank to the port
slop tank as necessary to receive the contents of Nos. 1 and 3 centre
cargo tanks, and tank washings from those tanks. When finished, close
- Drain the flushing water from cargo tanks 1 and 3. Open valves:
23 (No.1 centre cargo tank stripping suction).
59 and 60 (No.1 line block valves).
104 (No.1 line pumproom bulkhead suction).
144 (No.1 line suction to punp suction block valve).
124 (Pumproom suction crossover to No.1 pump).
162 (Stripping manifold valve to suction crossover line).
163 (Stripping pump discharge valve). 176 (stripper pumproom riser
233 (Stripping pump discharge to starboard slop tank).
- Start the stripping pump and drain No.1 centre cargo tank to the
starboard slop tank.
- Water wash No.1 centre cargo tank, according to the standard tank
- When all washing water is drained from No.1 centre tank, close
- Open valve 46 (No.3 centre cargo tank stripping suction).
- Drain tank flushing water from No.3 centre cargo tank to the starboard
- Water wash No.3 Centre Tank.
- Stop pump and close valve 46.
- Flush the No.1 bottom line forward, into the No.2 pipeline, and
into the port slop tank as directed when preparing for CBT operations,
(steps 7,1 to 7,6 in section 2.2.3).
The centre cargo tanks and No.1 pipeline are now prepared for taking
on additional ballast if necessary, without creating a dirty ballast
condition which might later delay operations at the loading port or
expose the vessel to a pollution claim.Ease vessel motion,
Vessel speed should always be reduced to ease vessel motions before
resorting to heavy weather ballast. Speed reduction will:
Reduce fuel consumption, and Save the extra fuel consumed for ballasting
and de-ballasting operations.