Angle of loll and Corrective action

Angle of loll

• It is the state of a ship that is unstable when upright and therefore takes on an angle of heel either to port or starboard.
• Angle at which a ship with initial negative metacentre height will lie at rest in still water.
• If the ship in further inclined to an angle greater than the angle of loll , then the sip will capsize.
• An initially unstable ship heels to certain angle and ends up in neutral stability.This angle is called angle of loll.
• At angle of lool , GM=0 or KG=KM

Corrective action

• First check if the vessel is listed or lolled.
• Always presume it is loll for safety and work accordingly.
• Calculate the volume of all tanks , check for any slack tanks.
• In a listed condition , always try to lower the CG by discharging the high side of the ballast first.
• Start filling the low side of the tanks( prefer small tanks to minimize the free surface effect during filling . Because if we fill the other side of the tank , the listing moment will be enough the capsize the ship
• Gradually start filling the mid tank and then the other side tank.
• Now the ship should be upright .If not try ballasting the other tanks in the same method
• During loll, never ballast the high side of the tank because the ship's listing moment to the other side is enough for it to capsize