Angle of loll
From Wikipedia, the free encyclopedia
Angle of loll relates to a specific hydrostatic stability condition experienced by unstable vessels at sea.[1][2][3]
Most conventional ship forms experience a shift in their centre of buoyancy as they heel. This transverse shift in the centre of buoyancy creates a righting moment which causes the ship to return to the upright condition.
If, as a ship heels, the centre of gravity moves transversly by a greater amount than the centre of buoyancy then the ship will continue to heel until a state of equilibrium re-occurs. Normally this state will not be attained until the ship has rotated 180 degress and therefore capsized. However, there are cases where the centre of buoyancy will, due to the shape of the ship's hull, "catch up" with the transverse shift in the centre of gravity and the ship will become stable again and rest at a static angle of heel.
This angle is known as the Angle of Loll and may be seen on the graph of static stability as a crossing point of the GZ curve and the horizontal axis with the slope of the curve having a positive gradient.
[edit] References
- ^ Stability Calculations - Estimating Centre of Gravity (Web - PDF available from link on page). Maritime & Coastguard Agency. Retrieved on January 24, 2007.
- ^ Definition - angle of loll (Web). Maritime Dictionary. Retrieved on January 24, 2007.
- ^ Stability Definitions (Web). MCA Orals. Retrieved on January 24, 2007.
