News story: How do you float a 65,000-tonne ship?

Last month saw the naming of the Royal Navy’s newest aircraft carrier, HMS Queen Elizabeth. Weighing in at 65,000 tonnes and with a flight deck measuring in at 4.5 acres, she is the largest warship ever built for the Royal Navy.

HMS Queen Elizabeth will provide a mobile air base for the UK’s armed forces.

She will be capable of launching, landing and maintaining aircraft 24-hours-a-day in support of war efforts and humanitarian aid and disaster relief operations. The carrier will operate worldwide with the new Joint Strike Fighter Lightning II jets and a number of types of helicopter.

Due to the size of the vessel and the importance of her role, stability is critical, especially for the taking-off and landing of aircraft. Indeed new ships and often those coming out of refit go through these tests. But how is this done?

A very accurate estimation of the ship’s weight and the particular location of the centre of gravity are required. Firstly, the build dock in Scotland was flooded very slowly so that the carrier was floating without any brows or cables attached, and with the mooring lines slack.

Weights were then moved a predetermined distance across the flight deck and the heel angle (how much the ship tips to one side or the other) was measured using pendulums set up on board.

Through various measurements of data it was possible to establish the weight of the ship and her centre of gravity.

This information will now allow the team to manage the condition of the ship during the final stages of build. It will also inform the decision on where to deploy the final quantity of solid ballast.

The ballast system will be used on board to keep the ship stable and level during her time at sea, even through heavy seas when tonnes of seawater are transferred around the ship.

Preparing the ship for her sea trials in 2017 will continue and flight trials with the Lighting II aircraft will take place in 2018. Work on HMS Queen Elizabeth’s sister ship, HMS Prince of Wales, is also underway.

Watch the float up and move of HMS Queen Elizabeth


Watch the float up and move of HMS Queen Elizabeth

Continue reading...
 
"We're sinking by the stern Sir."

"Have the Junior Rates move their porn collection up to the bows. That'll even up the flight deck and let us get some of the jets off."
 

Mattb

LE
According to what I remember from my physics GCSE and A-level:

"How do you float a 65,000 tonne ship"

The answer is "in 65,000 tonnes of water"


Talking out of my bum, via a mobile telephone.
 
How do you float a 65,000-tonne ship?


Make sure it displaces more than 65,000 tonnes


Graham Archimedes
Bath

Wrong. If it weighs 65000 tonnes, it displaces 65000 tonnes. It can't displace more than it weighs unless you have some other force counteracting the buoyancy.


According to what I remember from my physics GCSE and A-level:

"How do you float a 65,000 tonne ship"

The answer is "in 65,000 tonnes of water"


Talking out of my bum, via a mobile telephone.


Again, wrong. You could, theoretically, have a basin that was the same shape as the ship but ever so slightly bigger, so that the volume of the basin was 65,000,001 litres. Fill the basin with water then gently lower the ship into it, 65000 tonnes of water will be displaced, and spill out of the basin, and the ship, all 65000 tonnes, will be floating in one litre of water.
 

HarryBosch

War Hero
You could, theoretically, have a basin that was the same shape as the ship but ever so slightly bigger, so that the volume of the basin was 65,000,001 litres. Fill the basin with water then gently lower the ship into it, 65000 tonnes of water will be displaced, and spill out of the basin, and the ship, all 65000 tonnes, will be floating in one litre of water.

That is such a great answer. And an even better mental picture!
 
Wrong. If it weighs 65000 tonnes, it displaces 65000 tonnes. It can't displace more than it weighs unless you have some other force counteracting the buoyancy.





Again, wrong. You could, theoretically, have a basin that was the same shape as the ship but ever so slightly bigger, so that the volume of the basin was 65,000,001 litres. Fill the basin with water then gently lower the ship into it, 65000 tonnes of water will be displaced, and spill out of the basin, and the ship, all 65000 tonnes, will be floating in one litre of water.


Nonsence, take your witchcraft elsewhere, the 65,000 tonne ship will sink to the bottom of this basin, it will not float on a litre of water.
 

Guns

ADC
Moderator
Book Reviewer
In principe if the object is flat bottomed

In the case if the carrier you would need sufficient depth of water for keel clearance. If you don't it will topple and do an impression of an Argie Type 42 alongside.
 
Again, wrong. You could, theoretically, have a basin that was the same shape as the ship but ever so slightly bigger, so that the volume of the basin was 65,000,001 litres. Fill the basin with water then gently lower the ship into it, 65000 tonnes of water will be displaced, and spill out of the basin, and the ship, all 65000 tonnes, will be floating in one litre of water.

While that comes across as correct, it is in fact, unutterable bollocks.
 
While that comes across as correct, it is in fact, unutterable bollocks.
The bollocks bit is what you and Guns said. Read very carefully what I wrote. If the shape of the basin is very skilfully crafted to be only fractionally larger than the shape of the best object floating in it, the object will float, but in very little water. If you do not understand this, it means you are thick, not that I am wrong.
 
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HarryBosch

War Hero
While that comes across as correct, it is in fact, unutterable bollocks.

Okay ... but the use of 'comes across as' instead of 'is' leaves me wondering if Joe_Private's answer is 'correct but bollocks' in the sense that riding on a light beam and other thought experiments are correct but bollocks? So, ceteris paribus, is JP's answer correct? I have to say it sounds correct to me but then again my knowledge of physics is fairly basic.
 
Okay ... but the use of 'comes across as' instead of 'is' leaves me wondering if Joe_Private's answer is 'correct but bollocks' in the sense that riding on a light beam and other thought experiments are correct but bollocks? So, ceteris paribus, is JP's answer correct? I have to say it sounds correct to me but then again my knowledge of physics is fairly basic.

Of course it's sodding correct! Float an aircraft carrier in a basin, then brick by brick fill in the spaces between the basin sides and the carrier. Eventually, given small enough bricks, you will get rid of all but the smallest film of water, yet the aircraft carrier will still be floating, and the water will have fucked off over the side.
 
Of course it's sodding correct! Float an aircraft carrier in a basin, then brick by brick fill in the spaces between the basin sides and the carrier. Eventually, given small enough bricks, you will get rid of all but the smallest film of water, yet the aircraft carrier will still be floating, and the water will have fucked off over the side.

Never argue with an idiot...
 
The bollocks bit is what you and Guns said. Read very carefully what I wrote. If the shape of the basin is very skilfully crafted to be only fractionally larger than the shape of the best object floating in it, the object will float, but in very little water. If you do not understand this, it means you are thick, not that I am wrong.

There's not enough molecules of water in 1 litre to cover the required surface area of the ship, even at 1 molecule thickness of water.

You're wrong.

If, however, you had the minimum amount of water to cover sufficient surface area, you'd be correct.

If you do not understand this, it means I'm thick, not that you are right.
 
The answer must be aquaplaning which even enables heavy lorries to float on a thin film of water, e.g. on a motorway.

Not sure how fast a 65,000 tonne aircraft carrier would have to go and low bridges and gantries could pose problems.
 

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