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Mega yacht tonnage measurements

Discussion in 'General Yachting Discussion' started by German Yachting, Oct 16, 2020.

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  1. German Yachting, Oct 16, 2020
    #1
    German Yachting

    German Yachting Senior Member

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    I haven’t seen anything clear here but what convention is used for determining gross tonnage on mega yachts (e.g. these 50m being below 500gt)? The genesis of this question is the new Metal Shark Yachts M48 which they are reporting as 290gt which doesn’t pass the logic test for a 48m cat but upon further investigation, she is 290 US register gross tons or 653 ITC gross tons. Is ITC what is normally referenced for these yachts and licensing?
  2. Ken Bracewell, Oct 16, 2020
    #2
    Ken Bracewell

    Ken Bracewell Senior Member

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    Yes it is. Unless it has a US flag, that is.
  3. olderboater, Oct 16, 2020
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    olderboater

    olderboater Senior Member

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    And even the US builders reference ITC tonnage primarily. That's why 160-165' lengths are so popular, they come in just under 500 ITC. Then you extend that to a 172' so how do you make that work? Perhaps a beach club and now you're at 496 ITC.
  4. German Yachting, Oct 16, 2020
    #4
    German Yachting

    German Yachting Senior Member

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    Thanks all. I found it hard to believe a 48m cat would even be below 500gt so this helps clarify.
  5. Capt J, Oct 16, 2020
    #5
    Capt J

    Capt J Senior Member

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    It's a volumetric formula so cats would not have more tonnage on length due to the narrowness of the hulls.

    "Gross registered tonnage is a measurement of volume of all enclosed spaces on a ship with 100 cubic feet = to one ton. For instance, if the total cubic volume of all the enclosed spaces on a ship were 340,000 cubic feet, the gross registered tonnage will most likely be 3400 gross tons (340,000 cu. feet/100 cu feet/ton = 3400 Gross Tons)."
    http://www.themaritimesite.com/a-gu...e,cu. feet/100 cu feet/ton = 3400 Gross Tons).