Marine Engineering Study Materials

Grounding

Grounding means the vessel touching sea bed due to lack of depth of water or presence of protrusions from the sea bed. If the sea bed is soft, grounding may not cause any serious damage to the hull. However if hull touches any hard objects like rock, the shell plate may get dented deeply or even gashed. If the shell plate is cut open due to the grounding, sea water will get into the space thus opened to sea. This can result in ship taking dangerous list or even sinking unless proper action is taken immediately.

Checks During Grounding of Ships

1. In order to detect any ingress of water into the vessel after grounding, it is necessary to take soundings of all tanks at regular intervals.
2. Any increase in the tank level (or decrease if the grounding is by way of deep tanks having fluid to a level higher than water line) indicates that the tank boundary has suffered damages.
3. If a DB (double bottom) tank has been damaged and water ingresses into the tank, it is essential to ensure that the manhole covers of the concerned tank are closed tight.
4. Then the water ingress will stop as soon as the tank is full and the situation may be under control.

Damage Control on Grounding

• If a side tank has been ruptured and gets filled up, it may produce excessive list and it may be possible to correct the list by filling a similar tank on the other side. However this can result in an increase in draft which may prevent the vessel from berthing.
• If the breach is somewhere close to the water line, it may be possible to list the vessel to the opposite side of the breach so that water ingress can be reduced or even stopped.
• Efforts have to be made to close the hole produced by the grounding, from inside the space being flooded.
• If the water ingress can be stopped or reduced temporarily, closing of the hole by some suitable materials can be attempted.