What is a Ton in Boat Weight

[Dieseldude]

Originally Posted by El Pinguino

Over 59 years since I first went to sea and I had to wait for this thread to see the word 'mass' used when discussing 'tonnage'.

An obscure comment. By someone else who did not read the thread?

[aqfishing]

Originally Posted by boatpoker

As a Transport Canada Appointed and IMO Tonnage Measurer I think I have a clue

PS. Displacement tons are irrelevant to Tonnage Measurement.

As a matter of interest what system do they use on the registration papers for vessels in the USA, metric or imperial?

i.e for length, GT, displacement?

[StuM]

Originally Posted by aqfishing

As a matter of interest what system do they use on the registration papers for vessels in the USA, metric or imperial?

i.e for length, GT, displacement?

GT is neither metric nor imperial but can be calculated usng either metric or imperial units. Whichever system of units is used you end up with the same Gross Tonnage number.

[Briggers]

I was always under the impression that the weight of a boat was the weight of the amount of water it displaces?

[Dieseldude]

Originally Posted by Briggers

I was always under the impression that the weight of a boat was the weight of the amount of water it displaces?

You need to look back at the thread. There have been some good explanations given that tell the difference between displacement tonnage and registered tonnage. They are two very different matters.

[Montanan]

Originally Posted by aqfishing

Okay! Maybe I had too many whiskys!

Now that depends on how many ounces / milliliters you poured per serving of whiskey!


So to hijack this thread further, how much whiskey should one include per drink and should that be measured in mass or volume?



Now for an interesting story, linked below one can read how to properly age a whiskey by transporting such on a boat so as to allow it to slosh in the barrel and thus accelerate the flavoring. A story about Ocean Aged Jefferson Whiskey. Every well stocked boat's nautical liquor cabinet should have a bottle.

Lost At Sea, Deliberately: A Whiskey Aged On A Well-Traveled Boat
by Abram Brown Forbes Staff

Aug 13, 2014


https://www.forbes.com/sites/abrambr...h=44f477d47b51

Good to the last drop!

[MVDarlin]

USCG Docs have tonnage info is unrelated to the weight of the boat on the scales. It refers to the boats displacement.

[Adelie]

USCG documented tonnage has to do with volume that can be stowed, I think 1 tonn is about 35 cubic feet.

The etymology of use may have to do with tuns of wine.

[boatpoker]

Originally Posted by MVDarlin

USCG Docs have tonnage info is unrelated to the weight of the boat on the scales. It refers to the boats displacement.

Incorrect, displacement of the boat is it's weight.
See Archimedes Principle.

[Adelie]

Legally USCG documented tonnage is a volume, I did the calcs on my boat to see if the would document it.

Lexicon-wise you can talk about displacement as weight or volume:

dis·place·ment
/disˈplāsmənt/
Learn to pronounce
See definitions in:
All
Physics
Psychology
noun
noun: displacement; plural noun: displacements
1.
the moving of something from its place or position.
"vertical displacement of the shoreline"
the removal of someone or something by someone or something else which takes their place.
"males may be able to resist displacement by other males"
the enforced departure of people from their homes, typically because of war, persecution, or natural disaster.
"the displacement of farmers by guerrilla activity"
the amount by which a thing is moved from its normal position.
"a displacement of 6.8 meters along the San Andreas fault"
2.
the occupation by a submerged body or part of a body of a volume which would otherwise be occupied by a fluid.
the amount or weight of fluid that would fill the volume displaced by a floating ship, used as a measure of the ship's size.
"the submarine has a surface displacement of 2,185 tons"
TECHNICAL
the volume swept by a reciprocating system, as in a pump or engine.
"a fixed displacement gear"
3.
PSYCHOANALYSIS
the unconscious transfer of an intense emotion from its original object to another one.
"this phobia was linked with the displacement of fear of his father"
4.
PHYSICS
the component of an electric field due to free separated charges, regardless of any polarizing effects.
the vector representing electric displacement.
the flux density of electric displacement.

[StuM]

Originally Posted by MVDarlin

USCG Docs have tonnage info is unrelated to the weight of the boat on the scales. It refers to the boats displacement.

Sorry, but that's incorrect
"Weight of the boat on the scales" is displacement.
Archimedes showed that a loooong time ago.
If a boat weighs 10 tonnes, it will displace 10 tonnes of water.



Documented tonnage (gross and/or net) are essentially measures of the volume of enclosed spaces on the vessel.

It's worth noting that Gross/Net tonnage are actually dimensionless numbers. i.e. A vessel has a Gross tonnage of 50, not 50 tons/tonnes)

[valhalla360]

Originally Posted by Adelie

USCG documented tonnage has to do with volume that can be stowed, I think 1 tonn is about 35 cubic feet.

The etymology of use may have to do with tuns of wine.

True, it is related to a specifically sized barrel (the "tun" equal to 4 hogs heads) but the volume measurement for boats gets a bit wacky, particularly if the hull form deviates from an old wooden square rigger. Multihulls in particular can deviate drastically due to their extremely large beam.

[boatpoker]

Originally Posted by valhalla360

True, it is related to a specifically sized barrel (the "tun" equal to 4 hogs heads) but the volume measurement for boats gets a bit wacky, particularly if the hull form deviates from an old wooden square rigger. Multihulls in particular can deviate drastically due to their extremely large beam.

Volume is volume and cannot deviate and there is nothing wacky about
Archimedes Principle or Simpsons rule #3 ... it's just math.
The IMO does not allow "wacky" math.

[valhalla360]

Originally Posted by boatpoker

Volume is volume and cannot deviate and there is nothing wacky about
Archimedes Principle or Simpsons rule #3 ... it's just math.
The IMO does not allow "wacky" math.

Actual volume, sure but the formula the CG puts out...not so much.

I'm sure it works well for approximating an old square rigger but for a big racing trimaran, not so much. Of course, most racing trimarans aren't hauling much cargo so it's mostly just silly and irrelevant for your average cruiser.

I'd have to go pull it up but I believe our 8000lb catamaran was officially rated at 12 ton.

[danstanford]

Originally Posted by boatpoker

Volume is volume and cannot deviate and there is nothing wacky about
Archimedes Principle or Simpsons rule #3 ... it's just math.
The IMO does not allow "wacky" math.

Is the circular discussion here not related to the terms displacement and volume? Clearly the displacement is equal to the weight of the boat and I don't believe that is what tons in boat terms equals.
Volume and cargo capacity are different terms (from each other and from displacement) with the latter being the one measured in the OP's original question.