The Paradigm of “Actual” vs. “Assumed” Loading Conditions
William George
Marine Educator, Consultant and Expert Witness at William E. George and Associates, LLC
A paradigm is a generally accepted viewpoint of something at a given time.?It is very important that the ship’s Officer realize from the outset that the paradigm of the “actual loaded condition” is the vessel itself. The vessel should be considered a “full scale experiment” such that it is displaying its “actual condition”, as long as it is not aground, because it is in an equilibrium condition.?
On the other hand, the paradigm of a vessel’s loading computer, loading manual or trim and stability booklet represents only an “assumed loading condition” based on the data used to calculate this “assumed condition”. While these are great tools for planning a final loaded condition prior to the cargo operations, they seems to be of little help to the vessel’s officer when decisions need to be made as to where the last 2,000 tons of bulk cargo are to be loaded.?It has been the author’s experience to observe vessel officers using the ship’s loading computer or trim and stability booklet’s calculation forms as “trial and error” calculating devices rather than tools that confirms where and how much to load to achieve the desired stability, trim and hull strength.
The major point is that if an officer needs to know the actual condition of a vessel, he or she should read the vessel’s actual drafts!?In the following chapters, this book will demonstrate professional protocols for the ship’s officer to practice that will ensure the true condition of their vessel is known.
The Study of?“Stability, Trim and Hull Strength” vs. “Navigation”-- (An Analogy)
The subjects of Stability, Trim and Hull Strength are each related but different, however, they are no more difficult to master than Navigation and are not just for Deck Officers. In Navigation, we know where we are departing from and our destination.?Along the way the position of the vessel is determined to monitor the progress of the voyage and make sure hazards are avoided along the way.?In Navigation we constantly monitor the vessel’s actual position to a planned position in time.?This allows us to adjust our Course, Speed or ETA to the destination.
The problem in the past is that the subjects of stability, trim and hull strength have been approached as complete stand alone calculations with no reference to checking the vessel’s condition until all of the loading was more or less completed.?The same was done with the arrival condition at the next port.?The vessel’s arrival condition was calculated with the hope that it would be accurate when the vessel arrived at the next port with no means of checking for an actual worst-case condition prior to arrival.
While Trim, (the difference between the forward and after draft), can easily be checked by observing the vessel’s drafts, initial stability, (GM), is not as directly observable.?Hull strength can be somewhat observed by checking the vessel’s hull deflection.?My book, STABILITY AND TRIM FOR THE SHIP'S OFFICER, will strive to facilitate the ship’s Officer to understand that their vessel’s “actual condition” is observable and can be used to confirm the progress of cargo operation as well as a starting point to generate new calculations based on the “observed actual condition”.
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 print copies as well as an ebook (Kindle Version) available.
https://www.amazon.com/dp/0870335642/ref=tsm_1_fb_lk
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STABILITY AND TRIM FOR THE SHIP'S OFFICER, 4th Edition
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.
For more details or to enroll or contact me. Please respond to me directly by email me at:
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Port Captain, Merchant Maritime Deck Officer, Captain A-II/2, Marine Operation. Master in Operation Logistics and Management , Industrial Engineer.
2 年Captain for share your experience!. One of the biggest problem in large container ships to me was the undeclaired weight. I found researching 1 adittional ton per container on board on average undeclared, due to lack of special care in fill up the documents, under "said to weight". How to find out? as you advise, always compare reading draft, density, vs sounding, weights and ship stability. The diference is not "undeclared weight", is the lack of knowledge from people doing jobs of seaferer, without being real seaferer.
CEO & Principal Consultant, PMC Ltd.
2 年Strongly agree! Ship’s officers must physically read the ship’s drafts all around to verify the ship’s actual loading condition compared to the calculated loading condition of the loading plan throughout the loading process.