I read of a ship weighing 250,000 tons. How on earth can they weigh a ship that big?

Question

I read of a ship weighing 250,000 tons. How on earth can they weigh a ship that big?

Answer 1

Based on water displaced by the ship in cubic meters and converting the same to mass ( tons).

Answer 2

I hope you're joking.

Answer 3

Not weight of the ship itself  but the weight of the water that it displaces... Which can be calculated...

Answer 4

a bunch of VERY big cranes

Answer 5

As a lot of answerers before have said, its by displacement.

The method used is to fill a dry dock to a measured mark and measure the amount of water in it.

When a ship is then put into the dock and the water drained away, the difference between a dock full of water and a dock with both ship and water will be the  displaced water.

As a cubic meter of water weighs one tonne you only have to know the amount of water that flowed out of the dock to work out the displaced tonnage.

The amount of water is measured using flow meters.

I would also add that this method also takes account of displacement changes of the ship over its life due to modifications and additions.

Answer 6

work in out from the materials used to make it.

My boat was a custom built boat and not only did they know what it would weigh but they knew where to put the plimsol line before it went in the water so that means they also knew the displacement of the weight of the boat up the varying crossectino fo the hull.

those boat builders are clever buggers

I don't agree that they first weigh a boat based on testing its displacement. Sure, no doubt they do it as part of regular tests or surveys but surely no one is saying the first time they know the weight of a ship is when they float it !!

They KNOW what it weighs by the drawings. They must do because they've already marked the water line on the hull before it ever gets to the water.

Answer 7

The same way they know how heavy the Earth is.

Answer 8

As has been said the way that the displacement of the vessel is calculated is from the amount of water, by weight, that would fill the underwater volume of the vessel. Standard calculation for the Mate of a vessel carrying any cargo.

Answer 9

Easy, it is worked out during the light ship survey. This occurs right at the beginning of the vessels life cycle.

The classification society surveyor will survey the draft marks around the vessels hull to determine the depth of the vessel in the water when she is completely empty. The density and temperature of the water is also taken. (Various depending on where you are in the world)  

From this it can be determined how much water is being displaced by the hull and from that they can work out the weight of the steel used along with the weight of the machinery in the vessel. This will give you a figure called the dead weight tonnage.

Yes they do build them this big and here is the link to prove it.

Answer 10

OMG!!! you sound like my husband!! He's constantly amazed at how airplanes stay in the air and how ships float, and Lord God help you if you bring up a blimp!!!

Answer 11

Maybe they weigh all the parts before actually building the ship?

Answer 12

People - Don't be so judgemental.  The dumbest question is the one not asked.  The the weight is at best a estimate based on the amount of steel use in construction.   A good engineer should be able to give you and esimate by studying the design and calculating the amount of steel used.

Answer 13

they calculate the displacement of water then multiply by the percentage of the boat that is still above the water

Answer 14

Using the archimedes principle if you want to.

In reality the parts were probably weighed seperately.

Answer 15

They know the shape of the hull, and by figuring out how much of that volume is below the water line, they can calculate the weight of the water that would fill that volume.

That is the weight of the ship.

Answer 16

Before they make a ship they weigh the pieces so if somethingg is wrong then they can swap the piece for either heavier or lighter piece, and at the end they add all the pieces together to get the final weight.

Hope That Helps

x*x

Answer 17

Rochester Docks have a scale that weighs up to 6 million tons!

Answer 18

Humour , humour , humour..... are you serious?

All the weight is registered whilst 'in build' because the new owners have to pay for it!!!

Answer 19

Bit by bit silly..................but then science can measure lots of things without actually physically measuring it, iffa ya know whatta mean!

Answer 20

They tested and compared it to Simon Cowell's ego.  Simon lost - but only just.

They know the weight of all the parts - engineers have to know these things to calculate stress,buoyancy, balance and stability.

How much do you weigh?  lol

Answer 21

It's weighed indirectly based on the amount of water it displaces. If you know how much water weighs, and you can find the volume of the ship based on the shape of its hull, you can calculate how much water is displaced and thus the weight of the ship.

Answer 22

It's an approximate calculation, they consider the weight of the materials used to build it to a point.