Please be advised that there is an error in this video around minute 12:14 and again at 17:30. I mistakenly said that the angle of deck edge immersion occurred at 45 degrees, corresponding with the angle of heel associated with the maximum GZ. In fact deck edge immersion occurs somewhere closer to 30 degrees on this curve where you can see the slope of the curve reverse direction. This is called the "angle of contraflexure". You can see this more clearly in an image published by RoadToMates at Wordpress.com rtmates.files.wordpress.com/2012/08/gz-curve.jpg Thank you to Captain Handa for pointing this out to me.
i have a question about the way how to obtain the GM.In other videoes people teaching to draw a tagent line of the curve from 0 to the point of curve of 57.3 degree,is there any difference?
There are a number of ways to calculate GM. You can do it by a formula or graphically. Since M stays relatively fixed for initial stability (small inclinations) you can use the graphical method to calculate initial GM at 1 radian (57.3, degrees) the value of the GZ from the curve is equal to your Initial GM. Did that explanation help you at all?
@@deckprep Hi. So in other words we are simply drawing a vertical from 57.3 up to curve then going west to y to find the GM. Why the tangent line from 0? And how to we know the angle of that tangent line from 0 for larger inclinations? Thanks
With respect, at very begining where you added the two draft and took the mean and used it to extract displacement. This is wrong. Adding the drafts and dividing the result by two gives you Arithmatic mean draft. You need to calculate the TRUE mean draft before you enter the curves to extract dispacement.
Thanks for your comment. You are absolutely correct. That is how you would do it in the real world. However, all of the problems in my videos are actual questions on the US Deck License Exam. The method shown is the same as that used in the official answer to the exam questions. In actual practice the Observed drafts must be corrected to True drafts and then, for a merchant vessel, the Mean of Mean of Means Draft should be calculated and then used to enter the Hydrostatic tables. I teach my students how to do all of this in class but they are not required to do so on their license exam. Thanks again for your comment.
Please be advised that there is an error in this video around minute 12:14 and again at 17:30. I mistakenly said that the angle of deck edge immersion occurred at 45 degrees, corresponding with the angle of heel associated with the maximum GZ. In fact deck edge immersion occurs somewhere closer to 30 degrees on this curve where you can see the slope of the curve reverse direction. This is called the "angle of contraflexure". You can see this more clearly in an image published by RoadToMates at Wordpress.com rtmates.files.wordpress.com/2012/08/gz-curve.jpg Thank you to Captain Handa for pointing this out to me.
what a wonderful explanation sir, just wow..Thank u so much to make it so simple.
You are very welcome!
i have a question about the way how to obtain the GM.In other videoes people teaching to draw a tagent line of the curve from 0 to the point of curve of 57.3 degree,is there any difference?
There are a number of ways to calculate GM. You can do it by a formula or graphically. Since M stays relatively fixed for initial stability (small inclinations) you can use the graphical method to calculate initial GM at 1 radian (57.3, degrees) the value of the GZ from the curve is equal to your Initial GM. Did that explanation help you at all?
@@deckprep Hi. So in other words we are simply drawing a vertical from 57.3 up to curve then going west to y to find the GM. Why the tangent line from 0? And how to we know the angle of that tangent line from 0 for larger inclinations? Thanks
very well explained!
thanks for the explanation about gz correction
You are welcome Muhammad.
With respect, at very begining where you added the two draft and took the mean and used it to extract displacement. This is wrong. Adding the drafts and dividing the result by two gives you Arithmatic mean draft. You need to calculate the TRUE mean draft before you enter the curves to extract dispacement.
Thanks for your comment. You are absolutely correct. That is how you would do it in the real world. However, all of the problems in my videos are actual questions on the US Deck License Exam. The method shown is the same as that used in the official answer to the exam questions. In actual practice the Observed drafts must be corrected to True drafts and then, for a merchant vessel, the Mean of Mean of Means Draft should be calculated and then used to enter the Hydrostatic tables. I teach my students how to do all of this in class but they are not required to do so on their license exam. Thanks again for your comment.
please sine me up for your next continuing education courses!
Thanks for the feedback!