What are the corrective actions for angle of loll and list?

The following procedures should be carefully observed taken:
  1. Alter course to put the ship’s head into the predominant waves.

(If the ship is in a lolled situation it is essential that the ship stays lolled to the same side. Wave action may cause the ship to roll through the vertical to loll on the other side. This is a dangerous situation since the ship will heel from the vertical of it’s own accord and the momentum it will have in lolling over to the other side may be sufficient to capsize it. In any event, the ship will initially heel beyond the angle of loll before settling at the angle of loll whereby cargo shift may result, which will worsen the situation further.)

  1. Check that port and starboard listing moments are the same.

(By verifying tank soundings and checking for cargo shift it should be possible to account for any listing moments that may cause the ship to be in a listed situation. If it is calculated that there are no net listing moments then a case of instability may be assumed and the ship will be lying at an angle of loll. Recalculation of the ship’s effective KG should also be undertaken to verify the ship’s GM.)

  1. Check for slack tanks

(In carrying out (2) above it should also be evident if there are excessive free surface moments causing a loss of GM sufficient enough to make the ship unstable. In this case a loll situation may be confirmed.)

If a loll situation is confirmed:      
  1. Take action to lower G (reduce KG)

(It would be impractical to consider shifting weights on board using ship’s lifting equipment at sea. If the ship has high ballast tanks that are full then these may be emptied, discharging ballast from the high side tank first – the greater vertical distance between G of the ship and g of the weight being discharged will ensure that the greatest lowering of G will take place in the first instance. Once the high side tank is empty the one on the low side may then be emptied.)

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Empty high up ballast tank on the high side first to ensure greatest lowering of G

About the author

Amit Sharma

Graduated from M.E.R.I. Mumbai (Mumbai University), After a brief sailing founded this website with the idea to bring the maritime education online which must be free and available for all at all times and to find basic solutions that are of extreme importance to a seafarer by our innovative ideas.

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