# The Naked Scientists Forum

### Author Topic: What role does gravity play in sailing boats?  (Read 7035 times)

#### allan marsh

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##### What role does gravity play in sailing boats?
« on: 20/01/2015 21:02:09 »
If you know how a sailing ship can sail against the wind you know how important the keel,is.
If you consider gravity to be described as an imaginary wind vertically down to the mass.
So, how would you create a ship to sail into this wind and what item would the keel represent?

Imaginary but food for thought.
« Last Edit: 30/01/2015 20:51:48 by chris »

#### CliffordK

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##### Re: Gravity and sailing!
« Reply #1 on: 20/01/2015 23:47:47 »
Classic sailboats have a heavy keel to lower the center of gravity of the boat.
More modern ones have a light keel and water ballast tanks, serving the same purpose of lowering the center of gravity/balance to keep the boat upright, even with a strong wind.

The other purpose of the keel is to provide resistance in the water  to keep the boat from sliding sideways.

#### jeffreyH

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##### Re: Gravity and sailing!
« Reply #2 on: 21/01/2015 02:18:53 »
If you know how a sailing ship can sail against the wind you know how important the keel,is.
If you consider gravity to be described as an imaginary wind vertically down to the mass.
So, how would you create a ship to sail into this wind and what item would the keel represent?

Imaginary but food for thought.

To have an equivalence you would need the wind over the sea to operate on every particle in the boat equally so that no force is felt. You would also need to have the wind accelerate the boat in the direction of the wind. However this is unlike gravity as there is no centre of wind. There is a centre of gravity. This is like comparing chalk and cheese and expecting answers as to why they are comparable.

EDIT: Actually there is a centre of wind in either a tornado or hurricaine. The centre cancels the force as with the centre of gravity. Maybe wind can teach us something about gravity after all.
« Last Edit: 21/01/2015 02:21:50 by jeffreyH »

#### jccc

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##### Re: Gravity and sailing!
« Reply #3 on: 21/01/2015 06:49:36 »
We are sailing on gravity all the time. Move toward the direction of the force. The ground keeps us unmoved.

When we are falling or go down hill, we are sailing on gravity with the resistance of the wind or road.

Only if we can bend gravity, then we can sail on it. We don't have a way yet.

#### JohnDuffield

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##### Re: Gravity and sailing!
« Reply #4 on: 21/01/2015 13:44:15 »
If you know how a sailing ship can sail against the wind you know how important the keel is. If you consider gravity to be described as an imaginary wind vertically down to the mass. So, how would you create a ship to sail into this wind and what item would the keel represent?
You just can't do this. Gravity isn't like a wind. I'll try to explain:

Imagine you have a toy motor boat, and you're at a boating lake. You play around with your boat for a while. It's radio controlled. You can make it go around the lake at will. Only then I come along, and I do two things:

1) I jam the rudder of your boat hard to port.
2) I tip ten tons of jello into the left-hand side of the lake.

When you set your boat back in the water, all you can make it do is go round in circles. And because the water is now gooier on the left, your boat works its way over to the left. This is emulating an electron, and electron spin. If I were to retrieve your boat and remove the rudder, you would find it would veer to the left. This is emulating a photon. If I retrieve your boat again and put the rudder back and jam it hard to starboard, your boat would emulate a positron. It would still work its way over to the left. You don't have anything at your disposal to "sail against the wind", because gravity just isn't like some imaginary wind. Space isn't moving downwards in the room you're in. But it is inhomogeneous. You can see Einstein saying that here.

#### chiralSPO

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##### Re: Gravity and sailing!
« Reply #5 on: 21/01/2015 13:44:57 »
Wind isn't so much a force as a moving medium. Sailboats take advantage of friction (for both the sail and the keel/centerboard/daggerboard). Can one move upstream in a river (a case where there is a medium driven by gravity) by use of a keel alone? I don't think so...

#### allan marsh

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##### Re: Gravity and sailing!
« Reply #6 on: 21/01/2015 16:38:53 »
I like jccc answer.. Your correct.. But unless you believe the cosmos is only to be opened up by HSS or the like reaction engine.
Then.... We need to find the alternative to the sail and keel... Not obvious, but inevitable, except to those who don't believe in progress.

Try to explain henry XIII radio and television ...... He calls it works of the devil and black magic.

Come on folks...THINK!   What is your unknown unknown?

#### Colin2B

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##### Re: Gravity and sailing!
« Reply #7 on: 22/01/2015 14:20:50 »
Let's assume your hypothesis of a gravity wind. I'm not saying I agree with it.
Consider a soap box cart on a hill. You start downhill and accelerate, this is equivalent to running before the wind. The keel (wheels) are not needed to give any reaction force. You would need to consider the roadway preventing you falling towards the earth as being equivalent to buoyancy. Now steer to the right at 45deg downhill, now the keel is preventing you slipping sideways down hill, as it does in a boat. If you continue to turn you will eventually hit the no-go zone familiar to all sailors and you will stop. You have the equivalent of a very simple sail, so you cannot sail into the gravity wind, not because of a lack of keel, but because of a lack of the equivalent of an aerofoil sail. The keel is not the main problem.

The steepness of the hill might be seen as equivalent of wind strength, but the wind does not blow directly behind the cart. It blows down towards the centre of the earth, so you are only seeing an apparent wind. Think force triangles.
To sail upwind you would need to have the equivalent of an aerofoil for the wind to blow over. As far as I know (physicists help me out here) no one has detected a gravity wind that acts on anything. Experiments point to an attraction force. If you think of magnets, no one suggests a magnetic wind - in reality 2 winds one in each direction - pushing the magnets together. For gravity you would also need 2 winds in opposite directions, one pushing the cart towards the earth and one pushing the earth towards the cart. I don't think this has been detected and until it has there will be no clue as how it might be used. You would be looking for a material or shape that behaves differently from other mass under the influence of gravity. I'm not aware of anything at macro level, so you need to look at the subatomic research, your material should display a different mass under acceleration compared to under influence of gravity.
Your wind would have some interesting properties. The limiting speed for a simple, non aerofoil sail is the speed of the wind, but objects under gravity do not appear to have a limiting speed other than speed of light, does the gravity wind move at light speed? The energy imparted to a sail depends on the mass of the air particles hitting it, does the gravity wind have mass? Until you can answer these questions and find your anomalous material you can't begin to design a sail. Once you have a sail you might get a clue to a keel that doesn't depend on resistance of the  ground - remember keel and sail are both wings - in an atmosphere you could use a conventional wing for a flying machine.
Again physicists help me, but I believe all experiments to date have shown gravity to behave as an attractive force.

Thank you for the thought experiment, fun.

#### JohnDuffield

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##### Re: Gravity and sailing!
« Reply #8 on: 22/01/2015 14:44:57 »
I must reiterate, gravity is not like some wind. See Ned Wright's Deflection and Delay of Light and note this line: In a very real sense, the delay experienced by light passing a massive object is responsible for the deflection of the light. Light curves because space is inhomogeneous, like Einstein said, and it's modelled as curved spacetime.

#### yor_on

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##### Re: Gravity and sailing!
« Reply #9 on: 23/01/2015 19:33:50 »
Sweet idea :) And you can make a lot of it. then again, consider a ideal, eh, sphere (not spherical cow though, although I like that one). As far as I can see, in a 'flat neighborhood' the direction(s) must point to a center. And it shouldn't matter for it how you set your sails, unless you have the secret of 'anti gravity' at your helm.

#### yor_on

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##### Re: Gravity and sailing!
« Reply #10 on: 23/01/2015 19:40:50 »
"The USDA once wanted to make cows produce milk faster, to improve the
dairy industry.

So, they decided to consult the foremost biologists and recombinant
DNA technicians to build them a better cow.  They assembled this team
of great scientists, and gave them unlimited funding.  They requested
rare chemicals, weird bacteria, tons of quarantine equipment, there
was a horrible typhus epidemic they started by accident, and, 2 years
later, they came back with the "new, improved cow."  It had a milk
production improvement of 2% over the original.

They then tried with the greatest Nobel Prize winning chemists around.
They worked for six months, and, after requisitioning tons of chemical
equipment, and poisoning half the small town in Colorado where they
were working with a toxic cloud from one of their experiments, they
got a 5% improvement in milk output.

The physicists tried for a year, and, after ten thousand cows were
subjected to radiation therapy, they got a 1% improvement in output.

Finally, in desperation, they turned to the mathematicians.  The
foremost mathematician of his time offered to help them with the
problem.  Upon hearing the problem, he told the delegation that they
could come back in the morning and he would have solved the problem.
In the morning, they came back, and he handed them a piece of paper
with the computations for the new, 300% improved milk cow.

The plans began:

"A Proof of the Attainability of Increased Milk Output from Bovines:

Consider a spherical cow......" "

ahem :)

#### yor_on

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##### Re: Gravity and sailing!
« Reply #11 on: 23/01/2015 20:56:55 »
Don't know there?

Can you translate any shape into a sphere, of a even mass density? And does that matter?
Yep :)

#### JohnDuffield

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##### Re: Gravity and sailing!
« Reply #12 on: 24/01/2015 16:29:26 »
...unless you have the secret of 'anti gravity' at your helm.
It isn't anti-gravity. It's artificial gravity. You create a gravitational field above your ship to counteract the gravitational field of the Earth. Then you float. But it takes energy to go up. When you lift a brick, you do work on it.

#### yor_on

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##### Re: Gravity and sailing!
« Reply #13 on: 24/01/2015 20:44:01 »
I'm thinking of it this way John. You can only fall 'one way', into a 'gravity well' Doesn't matter if you have several acting on you, as you act on them. There's still only one direction. That should make a 'perfect sphere' of a even mass distribution, in a flat space, the smallest common nominator for describing gravity's direction, possibly? As for example a point like particle consisting of rest mass?? Let the arguments begin :)

#### jeffreyH

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##### Re: Gravity and sailing!
« Reply #14 on: 24/01/2015 21:02:50 »
...unless you have the secret of 'anti gravity' at your helm.
It isn't anti-gravity. It's artificial gravity. You create a gravitational field above your ship to counteract the gravitational field of the Earth. Then you float. But it takes energy to go up. When you lift a brick, you do work on it.

This must be the first post of yours that has had originality in it without trotting out stock responses. It actually demonstrates to me that you have put some thought into things. I do wish you would do more of this. OK you may be opened up to ridicule but what the hell.

#### jccc

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##### Re: Gravity and sailing!
« Reply #15 on: 24/01/2015 21:17:42 »
Gravity? Pete is the man!

Don't take my word, ask around.

#### Colin2B

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##### Re: Gravity and sailing!
« Reply #16 on: 29/01/2015 18:37:16 »
]It isn't anti-gravity. It's artificial gravity. You create a gravitational field above your ship to counteract the gravitational field of the Earth. Then you float. But it takes energy to go up. When you lift a brick, you do work on it.
When you say gravitational field, don't you mean gravity wind generator? I'm working on a rotor for one at the moment. I think I can curve it in spacetime, but I'm having trouble getting the Glue on in time.

#### jccc

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##### Re: Gravity and sailing!
« Reply #17 on: 29/01/2015 19:34:35 »
]It isn't anti-gravity. It's artificial gravity. You create a gravitational field above your ship to counteract the gravitational field of the Earth. Then you float. But it takes energy to go up. When you lift a brick, you do work on it.
When you say gravitational field, don't you mean gravity wind generator? I'm working on a rotor for one at the moment. I think I can curve it in spacetime, but I'm having trouble getting the Glue on in time.

I designed a thing to compress magnetic field/space for propulsion long ago, still don't have the means to test it.  Find a way to interact with gravity? You must find the nature/source/cause of gravity first.

Mind to tell your idea/ theory?

#### allan marsh

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##### Re: What role does gravity play in sailing boats?
« Reply #18 on: 05/02/2015 23:59:10 »
Long live imagination long live imagineering.  Do I appologies for stimulating thought.

Back to bananas and trees for some. I,d rather be in the Einstein 1905 camp!

#### The Naked Scientists Forum

##### Re: What role does gravity play in sailing boats?
« Reply #18 on: 05/02/2015 23:59:10 »