Which represents the righting arm?
A. GM
B. GZ
C. BM
D, KM
A. GM
B. GZ
C. BM
D, KM
Daily License Questions about Ship Stability and Trim: I just think people need to have some knowledge in their heads, professional or otherwise. After 2007 our world has changed due to the advent of Smart Phones. Retaining knowledge is like being able to play a musical instrument, if you do not use it you will lose it! The questions I post with will hopefully help you keep what you already know or remind you of what you should know. William E. George
As i previously posted, "GZ" is Righting Arm or Righting Lever or on Computers it is the "HBG".
ReplyDeleteThe best answer is B.
Do you agree or disagree?
Fully agree.
DeleteFully agree
ReplyDeleteGZ, the gizmo rights the boat.
ReplyDeleteI always wondered what that gizmo was for
DeleteFor small angles \:
ReplyDeleteGZ = GM x (sine of the angle of heel)
so if the GM = 1 meter or 3.28 feet and the vessel is heeled 3 degrees
the GZ, righting arm, = 1(sin 3 degrees) = 0.052 meters or 0.17 ft.
To find the righting moment in this situation simply multiply the GZ by the vessel's displacement. If the displacement was 10,000 metric tons, the righting moment will equal 520 m-metric tons!
Now if that could be made easy to remember you'd have it.
DeleteKen, it is just like playing music, you just need to practice until you know it. Once you know it then you can improvise. If you can improvise then you have mastered it. It just take practice!
ReplyDeleteIt has been said if you have a large enough lever you can lift or move anything. GZ is the lever. The weight of the vessel, the displacement, is the force, F=ma. Because the displacement of a vessel can be so relatively large, the GZ does not need to be.
I assume most people interested in this site have a desire to be a complete Master Mariners. I have always been surprized to see all the "Captains" at training facilities "abandon ship" when asked to teach a course in Basic Stability and Trim.
The world has already spoken. GZ is the righting arm:)
ReplyDeleteHowever at larger angles of heel, generally more than 15 degrees, the buoyancy force no longer acts vertically upwards through the initially defined metacentre(m).
Here, we must be very careful to use the "Wall Sided Formula" which is derived based on the principle of immersed and emerged wedges.
Further, the moment of statical stability at a large angle of heel may also be calculated by "Atwood's Formula" which introduces/utilizes a new parameter BR = horizontal shift in the centre of buoyancy = BG sin (angle of heel)