Cattle and buffalo have a higher water consumption than other livestock. The Australian Standards for the Export of Livestock 3.2 (ASEL) requires a minimum daily amount for potable water of 12% of the livestock weight. Cattle and buffalo produce dung with a high moisture content, upwards of 80% moisture. Higher water consumption will produce more urine and dung/urine mixture deposited on livestock cargo hold decks and hence more ammonia in cargo holds.

Marine Order 43 (Cargo and cargo handling – livestock) requires that the livestock operator must ensure that the air in a livestock space is as clean and fresh as practical. This would include ensuring air is as free from ammonia as practical.

The greater the deposit of dung/urine mixture on the cargo hold deck, the higher the uncertainties of displacement and vertical centre of gravity for a ship.

Appropriate deck washing helps ensure that the air in a cargo space is as clean as possible, and assists in improving the stability of the ship. Effective deck washing also assists in reducing the maintenance costs of these spaces.

It is the responsibility of the livestock operator to develop effective deck washing procedures, including incorporation of the intact stability requirements and necessary guidance for the Master and ship’s crew.

Based on Marine Order 43 stability criteria, ASEL stocking density and the AMSA approved intact stability books, AMSA recommends that deck washing is conducted at intervals not more than four days when carrying cattle and/or buffalo.

A sample deck wash procedure is shown below, which may be used as a guide for developing deck wash procedures.

1. Preparation for deck wash

1.1  Deck wash is required to be carried out after four days from departure and from previous deck wash, as referenced from intact stability booklet.

1.2  All crew should have read and understood the washing procedures within the Safety Management System (SMS) and be sufficiently familiar to undertake their tasks.

1.3  Chief Officer / Bosun should assess and guide the deck washing progress and monitor all stockmen to ensure that washing and cleaning procedures are complied with.

1.4  Prior washing a meeting should be conducted to ensure that washing procedures and instructions are understood by all participants.

1.5  Following procedures should be observed prior to washing.

1. The weather conditions and forecast should be favourable for deck washing.
2. The ship should be trimmed by the stern to assist in drainage (while ensuring an adequate reserve transverse metacentric height and stability range, in addition to meeting the Intact Stability (IS) Code and Marine Order 43 (MO43) stability criteria. The ship should not be heeled for deck wash as this will have the following adverse effects on stability of the ship and MO43 stability criteria will not be guaranteed to be met:
   • stability range will be reduced;
   • the reliability of the heeling levers due to shifts of livestock and fodder as determined as per Schedule 1 of MO43 will be adversely affected;
   • the ship will undergo additional heeling moment due to ballasting and/or de-ballasting of ballast water tanks and/or livestock fresh water tanks for the intended heel for deck wash; and
   • in addition to washed deck, effluents on unwashed decks will also move transversely and cause further list of the ship gradually.Empty all troughs and turn upside down.
3. Lay the washing hoses outside the pens and connect them to the appropriate water pump.
4. Check and clean all strainer plates at top of drainage pipes and strainer plates/gratings on drain wells to ensure the effluent and wastewater will flow smoothly during washing.
5. Portable kick plates if fitted should be removed.
6. Bilge pumps should be checked to ensure in working condition and drain wells should be checked to ensure empty or at low levels.
7. Advise the bridge that the deck team is ready for deck wash.

2. Deck washing

2.1  Start the appropriate water pump.

2.2  Livestock cargo holds should be washed from upper deck to lowest deck, and from forward to aft. In case there are two or more cargo holds on a deck, wash front cargo hold first, then middle cargo hold and then aft cargo hold.

2.3  Stockmen should stand outside the pens directing the wash hoses inside pens to ensure that the wastewater will flow towards the bilges through the drain pipes to prevent waste water flowing outside pens.

2.4  Two stockmen should be present in livestock spaces during washing, so that the washing will not impede the inspection and care of animals.

2.5  Wastewater level inside pens should be monitored and controlled to ensure that no area outside the washed pens, such as walkways or decks below are flooded with effluents and wash water.

2.6  Ensure effluent/wash water is drained smoothly to drain wells and pumped to holding tanks and then pumped overboard within the discharge rate as per section 13 of Record of Equipment and Arrangements (ROE&A) and MARPOL Annex IV requirements.

2.7  If there is an issue that is deemed to affect safety of the ship or welfare of livestock, stop the washing and report to the bridge immediately.

3. After washing

3.1  Clean all troughs and fill with fresh drinking water and fodder.

3.2  Put all portable kick plates in place.

3.3  Roll up all washing hoses and put them in place.

3.4  Check all drain wells and pump effluents to sewage tanks, if any.

3.5  All decks to be completely dry.

3.6  Bedding to be added when remaining voyage is more than 10 days.

3.7  Any wet areas to be spread with sawdust to prevent gases.

3.8  Advise the bridge that deck wash is completed.

3.9  Adjust trim and check intact stability of the ship, if necessary.

3.10  Enter details in log book for deck wash, including but not limited to date and time of start deck wash, and date and time to complete deck wash for each of all decks, new bedding added or not.