Purpose of the Water Ingress Monitor (WIM) for ships
Bulk carriers are renowned for sinking fast particularly if loaded with heavy cargoes such as iron ore. Possibility of ingress of sea water into cargo holds poses potential threat to ships . Masters of bulk carriers should be aware that the purpose of the Water Ingress Monitor (WIM) is to provide the maximum possible early warning of a condition that may seriously threaten the vessel's survival.
Bulk carriers, through necessity of the need to carry large volumes of bulk cargo, are fitted with cargo spaces that, in the event of flooding, represent a major loss of buoyancy. Added to this is the possibility that the cargo in the holds may be small in volume but high density, which allows for a larger volume of water to enter the hold than would be the case for vessels carrying lighter cargoes occupying larger volumes of internal space.
The Water Ingress Monitor therefore serves a similar function to a fire alarm. It signals a condition that requires immediate attention and could if the condition progresses - eventually lead to the need to evacuate the ship. For this reason the performance standard has been written to include many similar features to fire alarm systems.
In the event of an alarm sounding the officer of the watch should, without delay, attend to determining its precise nature. As with fire alarms, activation of the WIM should signal the first stage in going to emergency stations. After this first stage, which should include the mustering of all crew at their respective emergency stations, a responsible officer should be detailed to investigate the alarm.
Finding the reason of flooding
It is important that investigation is carried out responsibly and that the process does not endanger lives. Seafarers have been swept overboard in heavy weather conditions when they have ventured on deck to investigate a known ingress of water. Adverse weather conditions may make such operations extremely dangerous and masters should not commit crew members to open decks unless there is no alternative. In making such a decision masters should consider the value of such action. The purpose of WIM is to make it possible to know the condition in each hold without having to locally investigate.If an alarm is activated, the master should without delay - seek to verify the condition by reference to other indicators:
i) Is the vessel taking a list?
ii) Is the vessel trimming excessively
iii) Is anything visible on deck such as dislodged hatch covers and water emerging from spaces that would otherwise be dry?
These indicators may be provided by such systems as heel indicators, trim indicators and draft gauges. It should be remembered that the purpose of the investigation is to determine first, that a real alarm situation exists and second the extent to which the situation has progressed. The WIM may overtake this activity. For example, if an alarm has activated in one space and this is followed by another alarm, either in the same space or, more onerously in an adjacent space, it is reasonable to conclude that the situation is real. In the case of a bulk carrier, if two holds are flooding the ship almost certainly cannot remain afloat.
The master should act swiftly to protect the lives of those on board. Unless the vessel is in such shoal waters that grounding will occur before immersion of the hull, the crew should be prepared for abandoning the vessel without delay. Abandoning ship should only done after the verbal order from master . And master should consider it only as a last resort.
Precautions against ingress of water
Some key actions should be considered essential in the event of any activation of WIM. Vessel's crews should:
In the event of activation of a "pre-alarm", go to emergency stations. This should include :
i)preparation of life-saving appliances in readiness for evacuation but the craft should not be lowered or boarded.
ii) Alert shore rescue co-ordination stations using Urgency or if rapid sinking is detected early, Distress ;
iii) In the event of a main alarm, muster (all personnel) at abandon ship stations with the exception of those crew members engaged in investigation of the alarm and/or keeping systems running.
iv) Upgrade any urgency signal to one of Distress;
v) In the event of a second space alarm activation either Pre-alarm or Main alarm ensure all personnel are recalled from investigation and other duties and sent to abandon ship stations. This should include any crew remaining in the engine room or other spaces;
vi)Boats, Liferafts or Other Life saving craft must not be launched unless the specific order to do so has been given by the master.
The master should only order abandonship:
i) If the vessel is truly sinking. Checks of other indicators should be made quickly e.g. draft gauges, heel indicators,
ii) rapid air expulsion from vents serving spaces suspected of flooding, dislodgement of hatch covers, water emerging from spaces where it should not be expected;
iii) The depth of water is greater than the depth of the hull (a beached ship should not be abandoned);
iv) The speed of sinking is such that launching of life-saving craft must begin immediately in order to reach the water
Warning against flooding
Seafarers have been lost when bulk carriers have sunk due to having insufficient time to evacuate the vessel. Bulk carriers have, on occasions sunk so fast that not even distress signals were sent out. The facts made it mandatory on board functioning of water ingress alarms. If alarms frequently malfunction, the equipment should receive priority attention to rectify the fault. Crew members should not be reticent to muster.
If an alarm is false, the crew can be stood down, but if it is genuine and crew are not mustered, there could be insufficient time to do so if flooding progresses rapidly loss of sleep is less serious than loss of life. These are principles that are well established with fire alarms.
Flooding is potentially more serious than a fire that can be fought. Only the most serious fires can threaten the survivability of the ship in terms of buoyancy but flooding is the beginning of sinking. It should therefore be afforded higher status than fire.
Watertight doors Watertight doors that are used while at sea are to be sliding doors capable of being remotely closed from the bridge and are also to be operable locally from each side of bulkhead. Access doors, normally closed at sea may be of hinged-type with gaskets and dogs spaced and designed to ensure watertight closing. These closing appliances are to be provided with means of indicating locally and on the bridge whether they are open or closed.