World Library  
Flag as Inappropriate
Email this Article

Angle of loll

Article Id: WHEBN0007321377
Reproduction Date:

Title: Angle of loll  
Author: World Heritage Encyclopedia
Language: English
Subject: Ship measurements, Angle of list, Metacentric height, Loll, Naval architecture
Collection: Engineering Concepts, Naval Architecture, Ship Measurements
Publisher: World Heritage Encyclopedia
Publication
Date:
 

Angle of loll

Angle of loll

Angle of loll is the state of a ship that is unstable when upright (i.e. has a negative metacentric height, GMt) and therefore takes on an angle of heel to either port or starboard.

When a vessel has negative GM i.e., is in unstable equilibrium, any external force applied to the vessel will cause it to start heeling. As it heels, the moment of inertia of the vessel's waterplane (a plane intersecting the hull at the water's surface) increases, which increases the vessel's BM (distance from the center of buoyancy to the metacenter). Since there is relatively little change in KB (distance from the keel to the center of buoyancy) of the vessel, the KM (distance from keel to the metacenter) of the vessel increases.

At some angle of heel (say 10°), KM will increase sufficiently equal to KG (distance from the keel to the center of gravity), thus making GM of vessel equal to zero. When this occurs, the vessel goes to neutral equibrium, and the angle of heel at which it happens is called angle of loll. In other words, when an unstable vessel heels over towards a progressively increasing angle of heel, at a certain angle of heel, the center of buoyancy (B) may fall vertically below the center of gravity (G). Angle of list should not be confused with angle of loll. Angle of list is caused by unequal loading on either side of center line of vessel.

Although a vessel at angle of loll does display features of stable equilibrium, this is an extremely dangerous situation, and rapid remedial action is required to prevent the vessel from capsizing.[1][2][3][4]

It is often caused by the influence of a large free surface or the loss of stability due to damaged compartments. It is different from list in that the vessel is not induced to heel to one side or the other by the distribution of weight, it is merely incapable of maintaining a zero heel attitude.

See also

References

  1. ^ Kemp, "The Oxford Companion to Ships and the Sea", 1976, p. 494
  2. ^ "Stability Calculations - Estimating Center of Gravity". Maritime & Coastguard Agency. Retrieved 2007-01-24. 
  3. ^ "Definition - angle of loll". Maritime Dictionary. Retrieved 2007-01-24. 
  4. ^ "Stability Definitions". MCA Orals. Archived from the original on 26 January 2007. Retrieved 2007-01-24. 
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
 
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
 
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.
 


Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.