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Thread: Tonnage

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    Default Tonnage

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    Default Re: Tonnage

    Thanks Mike
    However i wonder then what the difference would be between the Deadweight and Displacement Tonnage, i ask as they look the same ??
    Cheers
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    Default Re: Tonnage

    Quote Originally Posted by Doc Vernon View Post
    Thanks Mike
    However i wonder then what the difference would be between the Deadweight and Displacement Tonnage, i ask as they look the same ??
    Cheers
    Looks like the difference in the deadwhieght tonnage is the space between tonnage and the keel is not taken into account Vern
    That's the way the mop flops.

    My thanks to Brian for this site.

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    Default Re: Tonnage

    #2. Two totally different things Displacement tonnage is the total weight of ship and cargo and is equal to the amount of water displaced by the vessel
    Deadweight tonnage is the the weight of cargo and stores the ship can carry at whatever seasonal zone she will be working at. It is more commonly known as the earning capacity of the vessel .
    The difference between loaded displacement and light displacent is your deadweight tonnage near enough for the learner of the carriage of commercial cargoes. JS

    PS your gross and Net Tonnage are not measurements of weight but of cubic of different areas of vessel and calculated at 100 cubic feet to a ton. JS

    For the serious wanting to know the loading of a ship ,one would have to learn about specific gravities or relative density’s of liquids , for example for very brief explanation , salt water is 1025 and fresh water is 1000.:if loading in say a water density of 1015 Then you could submerge the relative load line by 10/25; of the fresh water allowance for that particular vessel , just say the FWA was 10 inches , then you could submerge the relative load line by 4 inches. JS
    Last edited by j.sabourn; 19th January 2025 at 12:04 AM.
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    Default Re: Tonnage

    John.
    That was the reason I declined the great offer by my first Captain who asked me, if i would like to study for a second Mates ticket with the apprentices ,poor math's teaching at school, I think I could do it now though after Betty's teaching.
    Des
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    Default Re: Tonnage

    It’s not as hard as it appears Des, if you start at the bottom and work up, it’s just common sense , no one jumps straight in and starts at the top and works down. Unless of course you go back a couple of hundred years and buy a commission in the armed forces. The British merchant navy”s certification was at one time the best in the world and separated the poseurs from the professionals.Dont forget the housework today it’s Sunday , hope you get your $50 dollar bill back off the missus. Cheers JS.
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    Default Re: Tonnage

    Unfortunately the diagram without the relevant description of each condition of the diagram can lead the reader down the wrong path and thus draw the reader to the wrong conclusion convinced that they are correct in their conclusion.

    But at least it starts a discussion.

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    Default Re: Tonnage

    The description that should have accompanied the diagram in #1 Reads Verbatim

    Gross Register Tonnage (GRT) measures the vessels total internal volume (think engine rooms, cargo holds, living spaces) and influences port fees , safety rules and regulations.

    Net Register Tonnage (NRT) Focuses on cargo carrying spaces, representing the vessel's earning capacity.

    Deadweight Tonnage (DWT) The total weight a vessel can safely carry, including cargo, fuel and provisions. A critical metric for cargo planning.

    Displacement Tonnage The total weight of vessel and its contents- commonly used for naval vessels and stability analysis

    Lightweight Tonnage (LWT) The vessel's weight without fuel or cargo-important for ship valuation and scrapping

    Cargo Tonnage Represents the actual weight or volume of cargo carried

    Special Canal Tonnage Used specifically to calculate transit fees for the Panama and Suez canals

    The above is as printed alongside the diagram in #1.

    However it is an over simplification of actuality but will suffice for pub quizzes

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    Default Re: Tonnage

    Hi Ivan and John
    Al I have to do now is calculate the petrol left in the car to when the pension is due and work out if I can reach port in the RSL and retun homer, and I am Captain as well.LoL
    Des
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    Default Re: Tonnage

    It was usual for the Cheng to have a big say in this Des, the general rule was that one carried an extra 30 % for emergency’s for the expected burnout for a passage A to B. However this is where any friction usually occurred especially where one had a chief who was a hoarder and tried to hide extra to this hoped for surplus.
    This was always hard for him to keep mum about because when carrying a deadwight cargo it always involved arguments as showed up in the mates figures for cargo carried and thus large losses for the owners. One ship I was on long before the hoo hah about clean seas etc. pump out 300 tons over the side in the North Atlantic as became a huge embarrassment to him , apart from the huge loss of revenue at 100 pounds a ton at the time just think of the problems that could be caused by such actions . There is no room as far as I am concerned about secrecy on a ship when it involves such actions. So before filling up your car check with your Cheng your wife in this instance that she shows you the receipt of the filling of the cars tank. Cheers JS.
    Last edited by j.sabourn; 20th January 2025 at 12:35 AM.
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