SalemNews.com, Salem, MA

Opinion

Discussion

The Salem News has a real-name policy for commenting. Users may sign in using the Facebook Connect tool above the comments field. Once your first comment is posted by a moderator, all future comments will post automatically. If you prefer not to use Facebook, send an e-mail with your comments user name (which must be the same as your real name), city or town, street address and daytime phone number to comments@salemnews.com. A staff member will contact you directly to confirm your identity. It may take a day or two before you can post comments. Only your user name will be public. All users are required to follow our rules for commenting, which can be found here.

comments powered by Disqus
December 3, 2008

Letter: Center of buoyancy must be above center of gravity

To the editor:

I read with interest Paul Brailsford's Wednesday, Nov. 26, letter to the editor ("Minding the center is good politics, safe sailing").

It was very informative, particularly for your readers who may not be versed in the stability of marine vessels. However, I believe his statement that "... her center of gravity is situated on the ship's centerline at a calculated distance above the center of buoyancy so she is in stable equilibrium," is in error.

That relationship would ensure an unstable vessel that would certainly end up upside down! Conversely, the center of buoyancy must be above the center of gravity (the operative word here is "above") by a distance called the "metacentric height." This distance must be a positive number; i.e., buoyancy above gravity, to keep the vessel right side up.

The later statement: "Its distance in feet above the center of gravity ...," is indeed correct and indicates that the earlier statement was only an error in word juxtaposition, albeit a serious one.

Thomas E. Hoffman

Principal, Hoffman Design & Development

Marblehead

Text Only | Photo Reprints
Opinion

Nelson Benton Twitter Updates
Follow me on Twitter
Salem News Opinion Poll
AP Video
Syrian Boy Speaks Out, Survives Family Massacre Judge Tells John Edwards Jury: Keep Deliberating House Rejects Sex-selection Abortion Ban Bush, Obama on Stage Together Share Laughs SpaceX Dragon Returns to Earth Warming Gas Levels Hit 'Troubling Milestone' Youngest-ever Speller Disappointed by Mistake 2 American Tourists Kidnapped in Egypt Chen Guangcheng: 'Historic Transition' in China New York City Seeks Big Drink Ban Los Angeles Bans Plastic Grocery Bags Raw Video: SpaceX Dragon Leaves Space Station Police: Gunman Kills 5, Self in Seattle Experts: Americans Must Prepare for Storm Season Forest Fire Becomes New Mexico's Largest Ever Montreal Police: Mailed Body Parts From Same Man Facebook Expands Campus As Stock Shrinks
Comments Tracker
Roll Call
Helium debate
Helium