Talk:Metacentric height

message: This is wrong!! The inclining experiment is used to find the centre of gravity of a ship. The metacentre is calculated. The formula is  BM =\frac{I}{V} \  where I is the moment of inertia of the waterplane and V is volume of displacement.
At the moment I am working on a passenger ferry with an average GM of 5 metres which is a bit stiff but good if we ever get damaged. There is so much variation between different ships that you really cannot generalise here. 
I agree that it needs to be rewritten in a clear and logical way so that it can be easily understood.
{Welkinridge (talk) 17:55, 3 February 2008 (UTC)
thread_title: Measuring Metacentric Height?

message: Searching for "center of buoyancy" redirects to this article, but isn't defined until after it has been used.  Both it and "metacenter" need to be defined before metacentric height can be defined.  I suggest doing this in a separate article for "center of buoyancy".  ★NealMcB★ (talk) 15:51, 26 June 2011 (UTC)
thread_title:  Split "center of buoyancy"  into new article 

message: "Greater mass and/or arm length means a slower swing; and less mass and/or shorter arm length means a faster swing."
Source ?
Since when mass has any effect at all on roll period ?
Seems like total bogus to me. 87.95.47.187 (talk) 13:50, 3 December 2012 (UTC)
replies: text: You are correct for pendulums. See: period of oscillation. Seems to me other factors related fluid fiction are involved, but not mass. Dger (talk) 18:57, 3 December 2012 (UTC)
thread_title:  roll period 

message: in the section metacenter, the phrase starting by "G is" seems the result of a misended editing
in the section roll period GM is called stability index; if stability index is a synonymous of metacentric height, this should be stated at the start
I feel kind to point out that the metacentric height appears in the roll period in the opposite way that does a pendulum length.
About the mass-question immediately above, the mass does not appear but its distribution does (through the barycenter position and the gyration radius); perhaps this may be stated more clearly (the compromise between the needs of expert and non-expert readers is hard)
May help something like "Insofar gravity is the only force (buoyancy arises from the gravity on the fluid), the total mass cannot appear in the kinematic equations and formulae".
I am not native english and I find the style "too little international"
pietro
188.14.97.4 (talk) 16:44, 27 September 2016 (UTC)
thread_title:  comments 

message: 1) Metacenter as a point might be well defined, but apparently means both M0 (the original position when ship is not heeled) and instantaneous position as a function of heeling angle.
Metacentric height is not. Is it:
a) GM
b) KM
c) BM
If the term has a clear meaning it should be defined, not left to be guessed.
2a) "Ignoring the ballast, wide and shallow or narrow and deep means that the ship is very quick to roll and very hard to overturn and is stiff"
Really? Narrow and deep means that B is well below surface of the water but as K is even deeper, KB has a large value. If there would be a lot of ballast placing G close to K, it would mean a stiff hull. But when ballast is ignored, G might be at the waterline. In that case GM might even become negative, implying just the opposite that is claimed. In that case if the hull remains watertight at 90 degrees heel, it will be stiff at that position. If not it might sink or totally overturn.
2b) "If a ship floods, the loss of stability is caused by the increase in KB, the centre of buoyancy, and the loss of waterplane area - thus a loss of the waterplane moment of inertia - which decreases the metacentric height"
Interesting. in 2a) it was claimed that increase in KB improves stability and makes the hull stiff, now it's just the opposite.
In correct text, it should point out that if for some reason there would be no free surface due to flooding, if (as is common) added mass of water due to flooding is located below added center of buoyancy (which is located above where waterline used to be before flooding took place using ship fixed co-ordinates), it is certain that righting moment will increase (although righting arm might not), and in any other case righting moment will decrease.
3) Under header free surface effect:
"This results in a displacement of the centre of gravity of the tank or space relative to the overall centre of gravity."
Correct, but a very important issue is ignored. In which direction does the center of gravity move, and does it improve the righting moment or just the opposite?
It turns out that in some sailing boats with very high angle of heel (but still less that angle of vanishing stability =AofVS) the righting moment will indeed improve. If this is the case the typical angle of heel is around of 135 degrees and the effect can even improve AofVS. And even better, for practically all sailing monohulls the effect of free surface will help to right the boat from 180 degrees angle of heel.
5.61.93.234 (talk) 18:40, 7 March 2019 (UTC)
thread_title:  ambiguous and contradictory article 

message: I am working on a robotics course and am copying content to the following site:
https://en.wikiversity.org/wiki/Robotic_Mechanics_and_Modeling/Vehicles
Admazzeo (talk) 18:03, 18 February 2020 (UTC)
thread_title:  Material Copied to Wikiversity