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Risk of Partially filled ballast holds or tanks of a seagoing bulk carrier

Sailing with partially filled ballast holds is prohibited unless the approved loading manual approves of such a practice. Cargo holds designed for partially filled in harbour for the purpose of reducing the ship's air draught are not to contain any water ballast while at sea.

Where ballast holds, and in some instances ballast tanks, are partially filled, there is the likelihood of sloshing. Sloshing is the violent movement of the fluid's surface in partially filled tanks or holds resulting from the motion of the ship in a seaway.

Sloshing will result in the magnification of dynamic internal pressures acting on the hold/tank boundaries. For any tank design, dimensions, internal stiffening and filling level, a natural period (frequency) of the fluid exists, which, if excited by the ship's motions, can result in very high pressure magnification (resonance) which can result in damage to the tank/hold's internal structure.

To minimise the effects of sloshing, the liquid's motion needs to be controlled by ensuring that tanks are either pressed up or empty (sloshing can occur at low filling levels).

Where a ship has been specially designed for partially filled ballast tanks and/or hold(s) whilst at sea, the filling levels specified in the ship's loading manual are to be followed.

Designated Ballast Hold

When using the vessel's ballast hold for long sea passages in ballast condition, the operation of ballasting or deballasting is to be supervised directly by the Chief Officer, the Master being responsible for ensuring that this operation is carried out in the correct manner. The Master is never to put to sea with this hold partly filled, and the ballasting operation must be completed before proceeding.

Charterers and Owners must be informed well beforehand of the time required to complete this, and if necessary, arrangements will be made for the vessel to proceed to a safe anchorage for this purpose. Similarly, the Master should not commence deballasting of the hold until the vessel has arrived at a safe anchorage. Under extenuating circumstances, permission may be requested from the management office to deballast the hold at another location subject to a full risk assessment having been completed.

Before commencing the ballasting/deballasting operation, all extra ballast vents must be fully opened and checked by the Chief Officer, to facilitate the entry/exit of increased airflow due to the large volume of water involved. Ideally, and if weather permits, the main hatch cover is to be opened as this will remove any doubt as to the adequacy of air entry/exits facilities and permit better observation of progress.

It is the Officer on watch’s responsibility to ensure that the hold ballast line is blanked off properly in the hold, thus avoiding any risk of accidental entry of water into cargo hold after loading. The Chief Officer is to personally to check this, and report to the Master.

Related guideline

  1. Ballast exchange procedure at sea

  2. Practical method for the control of transportation of harmful marine organisms

  3. Safety precautions during ballast operation

  4. Loading of high density cargo and water ballast distribution for bulk carriers

  5. Regulation of pumping system of bulk carriers

  6. Handling water ingress problems in bulk carrier, investigation and countermeasures

Reference publications

  1. MARPOL 73/78
  2. IMO Resolution A.774 (18) – “Guidelines for Preventing the Introduction of Unwanted Aquatic Organisms and Pathogens from Ship’s Ballast Water and Sediment Discharged”
  3. Ship’s “Procedure and Arrangements manual” (Approved by Class)
  4. Guide to Port Entry
  5. US NPDES Vessel General Permit Compliance Manual
Our detail pages illustrated many safety aspects of Bulk carrier

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Top articles

  1. Loading of high density cargo and water ballast distribution for bulk carriers

  2. Regulation of pumping system of bulk carriers

  3. Handling water ingress problems in bulk carrier, investigation and countermeasures

  4. Survival and safety procedure for bulk carriers

  5. Suitability of Shore Terminals for handling bulk cargo

  6. Preparation for ships carrying bulk cargo & standard loading condition

Operation of sea going bulk carriers involved numerous hazards . Careful planning and exercising due caution for all critical shipboard matters are important . This site is a quick reference to international shipping community with guidance and information on the loading and discharging of modern bulk carriers so as to remain within the limitations as specified by the classification society.
It is vital to reduce the likelihood of over-stressing the ship's structure and also complying with all essential safety measures for a safe passage at sea. Our detail pages contain various bulk carrier related topics that might be useful for people working on board and those who working ashore in the terminal. For any remarks please Contact us

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