Welcome back to The Word This Week. We are on our fourth week in this series and the word for the Week is “Lightweight” as a term of measurement for a ship or floating asset. (I apologize for the length of the video this week, I was getting in to it a bit much) Actually the term lightweight tons is exactly what it infers. The weight of a ship with all of its structure including all steel, decks, machinery, and cargo gear when it is light, or without the cargo, ballast, fuel oil, lube oil crew or consumables. The absolute lightest weight of the ship. Even though it is a simple inference, this term is often confused with the other terms of measurement for ships. These terms are, Deadweight Tons, Displacement Tons, Gross Tonnage and Net Tonnage.
These are the definitions:
Lightweight Tonnage: The weight of a ship with all of its structure including all steel, decks, machinery, and cargo gear when it is light, or without the cargo, ballast, fuel oil, lube oil, crew, passengers, or consumables.
Displacement Tonnage: The total weight of the water a ship displaces as it sits freely floating in the water.
Deadweight Tonnage: The sum of the weights of a ships cargo, ballast, fuel oil, lube oil, crew, passengers and consumables. Or the displacement tonnage minus the lightweight tonnage.
Gross Tonnage: A unitless number based all enclosed spaces of the ship. It is not a mass or weight. It is typically used to as a basis for a ship’s manning regulations, safety rules, registration fees, and port dues.
Net Tonnage: A unitless number based on the total enclosed volume of the ship’s cargo spaces which is calculated by using a mathematical formula. It is not a mass or weight. It is commonly used for the basis of determination of port duties or fees.
These terms are all used frequently in the maritime industry and have relevance for naval architechs, marine engineers, nautical mariners and commercial shipping and trade in general. If these words were seemingly confusing to you before, I hope you have a better understanding now. Another Word This Week; Lightweight.
For the word next week, we are going away using a word that is used in the drilling industry. It also has relevance in the tanker industry. The word is Tribocharging. Think hard about this word, do you know its meaning? If you know the meaning or have comments, please drop me a note on LinkedIn, Twitter, or Facebook.
Until next week, be safe in all that you do,
Leonard Hale PMP
