BEYOND ADVANCED STABILITY PRIVATE LESSONS
William George
Marine Educator, Consultant and Expert Witness at William E. George and Associates, LLC
Here is a sample of one private lesson with a New Student.
This is not for everyone. It is not License Prep. You will learn how to improvise Stability and Trim Solutions via email lesson with me. This can be used for many things like Topping Off a Ship, Planning Maximum Cargo, Dead Freight Surveys, Dealing with Draft Restrictions, Things Not Normally Asked on a License Exam, etc.
William George: Welcome Aboard!
Student: I'm very in interested in the advanced stability that you teach.
William George: Ok, let us start with something basic.
Q: What to the required LCG for a zero trim condition for a ship arriving at a restricted draft of 13 meters. The Harbor Water density is 1.025.
Student: I couldn’t understand the question,?I understood that LCG is required, right??If so,?for zero trim condition, LCG equals to LCB , and if the ship is box shaped, so, CB will be at midship. But, I don’t know how I will use the given draft?!!?
William George: It does not matter. Simply look up the LCB for the draft using the zero trim Hydrostatic Data. The answer is LCB if you used the Hydrostatic Tables calculated for zero trim!?
William George: Moving on, let us try another question.
Q: Estimate the Displacement of a small commercial fishing boat vessel that has no draft marks or Hydrostatic Data.
Student: Displacement = lightship weight + Dead weight.
William George: You are not given any information about the vessel. You only have the vessel. No builders data. It is just a big old wooden commercial fishing boat. It does have a pilot house and a mast. Try again.
Need a hint? You can use a known weight.
Student: This weight we move it with a specific distance and get its moment which will be equals to the moment of disp. * GG1?
If we know GG1, the disp will be found.
m*d = Disp. * GG1?
GG1 is the distance between the new and old center of gravity.
William George: Which way did you shift the weight? How did you actually calculate GG1? You cannot pull GG1 out of thin air. Your answer is incomplete!
Student: Is any another data given ?!? LCG of the ship or GM ?
William George: Hint, you need to determine the change in GM.? You do not have KM because there is no Hydrostatic Data. The vessel is afloat.
Reminder: the answer is "how to do it".?What is old is new again.
Hint: How can you estimate GM without Hydrostatic Data?
Please review these video clips of mine, they are on YouTube. Sorry for the ads if they pop-up!
https://youtu.be/LKOWaJqPr5o
GM =(0.8B/T)^2
Where T= full rolling period in seconds and B = Beam in Meters.
It works for Boats and Ships!
Student: If we got GM from the relation you provide, we may perform the inclining experiment and get Displacement from the following relation?
Tan(theta) = m*d/Disp.*GM
William George: Think vertically. Then you do not need to construct a pendulum to measure the deflection. When we shift the weight vertically, the Metacenter where ever it is does not move and Display is constant. By doing a rolling test before and after the vertical shift the difference between the two GMs = GG1.
Knowing: GG1 = Md/ Displ
Then: As you stated before?Displ = m*d/GG1
Did you watch the videos?
Student: Smart method?
William George: My invention. Thanks. Beyond Advanced Stability is like Jazz Music. You can learn to improvise.
Student: But how you exactly be assure that the rolling test is the same before and after shifting the weight. It depends on your manual pushing of the vessel so it may be different.?
Secondly, you calculate the the period time by counting the number of cycles but as the time passes the cycles amplitudes are reduced, so how you be assure that this is accurate.
William George: Each vessel with positive initial stability has simple harmonic motion. The roll period is measured after the excitation force stops. Watch the videos again. The amplitude of roll angle fades out, the period or frequency remains constant.
Student: Ok I got it. Thanks for your clarification.
William George: You're welcome.
Student: Have you more questions ?!
William George: This is what I do. I teach mostly Ship's Captains and Chief Mates and those who want to know.
To receive more information?to become one of my Private Students please respond?to me directly or email me at:
More Information about my Bunker and Draft Survey Course
My?Bunker and Draft Survey Course?is a narrated correspondence course done via email worldwide. Sadly, most Maritime Schools and Academies do not include Draft and Bunker Surveying in their curriculums because it is not included on the License Exams. As a result they do not prepare you to work on this type of ship.
Did you know that a Draft Survey properly done can yield the Total Displacement within 0.5% of the true cargo figure or Displacement if done properly? You can determine a vessel's total cargo weight by reading the drafts and sounding the tanks instead of the cargo manifest which may or may not be correct or verify a Shore Scale Weight. This method works on all vessels as long as they are afloat. You can also use Draft Surveying to independently confirm a vessel's Stability Calculations.
Years ago, I got a great job and a 38 year career, because I knew about SHIPS, STABILITY & TRIM and DRAFT SURVEYING calculations. This Course is a good way to complete your professional education.
To learn about becoming one of my private remote Students or attending an upcoming live event at MITAGS-West, Seattle, Washington, USA.
In November 2022: BEYOND BASIC STABILITY WORKSHOP: Planning a Maximum Load for Restricted Draft Arrivals or Canal Transits.
In December 2022: BUNKER AND DRAFT SURVEY COURSE LIVE
For more details, event lodging and to register. Please respond to me directly by email me at:
Looking for a copy of my book,?STABILITY AND TRIM FOR THE SHIP'S OFFICER, 4th Edition?
You can find it on AMAZON.COM there are new and used copies available.
https://www.amazon.com/dp/0870335642/ref=tsm_1_fb_lk
If you like my book, you will like my Podcasts about the book.
STABILITY AND TRIM FOR THE SHIP'S OFFICER, 4th Edition
https://podcasts.apple.com/us/podcast/stability-trim-for-the-ships-officer/id1493267414
Do you have questions or feedback? Let me know.
Safety ( BOSIET, ISPON & IFIA CERTIFIED )
2 年Love to learn
Retired Canadian Coast Guard Safety and Security Superintendent, DPA, CSO, Member of My Ocean Life - CHA Member - Hydrospatial Advocate - #Hydrospatial
2 年Wonderful stuff Mr George. I would recommend it to Chief Officers and Captains who have to do their cargo and ship stability and are unsure of the shipboard computer program.