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Can you really raise a ship with hot air

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InOBU 09 Sep 03 - 11:58 AM
Amos 09 Sep 03 - 12:07 PM
Desert Dancer 09 Sep 03 - 12:14 PM
Hovering Bob 09 Sep 03 - 12:25 PM
Amos 09 Sep 03 - 12:25 PM
Amos 09 Sep 03 - 12:28 PM
Nigel Parsons 09 Sep 03 - 12:30 PM
Kevin Sheils 09 Sep 03 - 12:37 PM
Desert Dancer 09 Sep 03 - 12:43 PM
Amos 09 Sep 03 - 12:51 PM
Chief Chaos 09 Sep 03 - 12:57 PM
dick greenhaus 09 Sep 03 - 01:51 PM
Amos 09 Sep 03 - 02:40 PM
McGrath of Harlow 09 Sep 03 - 04:08 PM
Chief Chaos 09 Sep 03 - 04:30 PM
TIA 09 Sep 03 - 04:52 PM
Amos 09 Sep 03 - 04:55 PM
Gareth 09 Sep 03 - 05:05 PM
MudGuard 09 Sep 03 - 05:07 PM
Don Firth 09 Sep 03 - 05:36 PM
MudGuard 09 Sep 03 - 05:45 PM
Gareth 09 Sep 03 - 07:01 PM
Amos 09 Sep 03 - 08:50 PM
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Subject: Can you really raise a ship with hot air
From: InOBU
Date: 09 Sep 03 - 11:58 AM

Well... I propose that we take all the discussion of sinking vessels with augers, a truely interesting thread, (I really mean it, I am not being sarcastic, it it indicative of the well versed folkies which meet around this table...) but, I do believe that we are on to something here... I believe if we can package the hot air of this conversation, as well as adding a little of the gasses which our brother Spaw is famouse for (add 1 pound of baked beans and ferment...) pipe it into say, the Andrea Doria... well we'd be rich salvors!
Let's give it a try...
Cheers
Larry


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Subject: RE: Can you really raise a ship with hot air
From: Amos
Date: 09 Sep 03 - 12:07 PM

Larry:

You don't need hot air to raise a sunken vessel!! Any air will serve. The reason hot air "raises" things (like baloons) on land is because it is displaced by colder air. Under water ANY air will be displaced by water.

A


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Subject: RE: Can you really raise a ship with hot air
From: Desert Dancer
Date: 09 Sep 03 - 12:14 PM

Depends how high you want to raise it, Amos, and whether you're starting below or on the surface. ;-)

~ Becky in Tucson


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Subject: RE: Can you really raise a ship with hot air
From: Hovering Bob
Date: 09 Sep 03 - 12:25 PM

This reminds me of a discussion, all right an argument, that I had as a young lad with my cousin. We were on a beach, watching some pedalos bobbing about and my Cousin maintained, very forcibly - he was bigger than me, that if the floats were filled with compressed air, they would be more buoyant than floats filled with air at atmospheric pressure. He reasoned that air was lighter than water so, therefore if you could get more air in to the floats, the lighter they would be. My argument, which cost me a bloody nose by the way, was that a partial vacuum in the floats would make then lighter.


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Subject: RE: Can you really raise a ship with hot air
From: Amos
Date: 09 Sep 03 - 12:25 PM

Sunken means below the surface, Becky. And typically one raises sunken vessels as far as sea level and then drags them ashore for repairs or whatever... Now if you want to take a deadweight like the Andrea and make it into a hot air-lift balloon sort of vehicle it will take a lot more acreage than Larry is proposing. Air doesn't really lift that well, even when heated. Helium or hydrogen lifts better,but look at the size of the bags needed in dirigibles. The ship in question was solid steel and cast iron; the biggest dirigibles such as the Hindenberg built their modukles of aluminum where possible for lightness.

Oh, well, what the hey -- it's a fantasy thread, anyway, innit? Getting rich by accomplishing the impossible. Wodda concept!

A


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Subject: RE: Can you really raise a ship with hot air
From: Amos
Date: 09 Sep 03 - 12:28 PM

Bob:

Displacement is by volume. Larger floats would lift more, yes. Compressed air is heavier than normal air. Your angry cousin was like thew businessman who sold his products at a loss, while hoping to make it up on volume!

A


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Subject: RE: Can you really raise a ship with hot air
From: Nigel Parsons
Date: 09 Sep 03 - 12:30 PM

Interesting question.
Surely it depends on the size of the ship & the depth at which it lies. Whilst a well costructed 9hull will float on the surface because of its displacement (taking into account its average density, including the air it holds) once it has sunk, the same amount of air may be insufficient to raise it. Air gives a good lift in water because of the relative densities, but at depth the air will be compressed by a much greater factor than the water, thus bringing the relative densities of Ship+Air and Water much closer.
Free divers (a sport in the news recently) know that there is a depth at which the natural positive bouyancy of a human body becomes a negative quantity.

Nigel


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Subject: RE: Can you really raise a ship with hot air
From: Kevin Sheils
Date: 09 Sep 03 - 12:37 PM

Is this thread about the Mary Ellen Farter?

I'll get me coat.


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Subject: RE: Can you really raise a ship with hot air
From: Desert Dancer
Date: 09 Sep 03 - 12:43 PM

Well... Amos, you caught me just popping off a response to the thread title without paying attention to the details of the inquiry.

40 lashes with a wet noodle for me for wonton contribution to atmospheric warming, I guess.

~ B in T


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Subject: RE: Can you really raise a ship with hot air
From: Amos
Date: 09 Sep 03 - 12:51 PM

LOL! Oh, you wonton!


A


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Subject: RE: Can you really raise a ship with hot air
From: Chief Chaos
Date: 09 Sep 03 - 12:57 PM

Interesting discussion. Air bags are used all the time in the recovery of sunken vessels, usually in shallower water. As stated before the depth (pressure) pretty much makes recovery of deeply sunken vsls near impossible. Sure it could be done, but at what cost? And there are definite safety factors to be considered. All in all it wouldn't be worth it.
The best way to go about it would be to place air bags within the structure of the ship (displaces water) and uses the ships own superstructure as a control factor (lessening the number of cables needed (the less amount of lines in the water around propellers the better)). Lightening the load prior to bringing her up (water weight vs. cargo/unnecessary gear weight). Bottom suction calculations, deterioration of the hull, achieving neutral bouyancy so she doesn't come up like an emergency breaching submarine and crack into pieces when she hits the water. There are a lot more factors to consider.


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Subject: RE: Can you really raise a ship with hot air
From: dick greenhaus
Date: 09 Sep 03 - 01:51 PM

Well, pingpong balls have been used successfully. Not hot ones, though.


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Subject: RE: Can you really raise a ship with hot air
From: Amos
Date: 09 Sep 03 - 02:40 PM

I have seen some uses for pingpong balls which it seems would be well suited for heated ones. Further, deponent sayeth not.

A


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Subject: RE: Can you really raise a ship with hot air
From: McGrath of Harlow
Date: 09 Sep 03 - 04:08 PM

Hot air would in theory lift better than cold air.

Air expands when heated, which would mean that to fill a given volume at a given pressure you'd need fewer molecules of air. So the differential between the weight of the air and the weight of the water it displaces would be greater; hence, more lift.


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Subject: RE: Can you really raise a ship with hot air
From: Chief Chaos
Date: 09 Sep 03 - 04:30 PM

At those depths and pressures the differences between hot air / cold air would be minimal at best. then there's the problem of how to heat the air either on location or from the surface and keeping it hot until it gets to the air bag. Good luck!


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Subject: RE: Can you really raise a ship with hot air
From: TIA
Date: 09 Sep 03 - 04:52 PM

Excellent point Nigel.

Okay, somebody check my math please.

According to the ideal gas law PV=nRT. Avogadro's n is a constant, and we can pretend that R and T are as well (to make it simple enough for me to handle). So, P (pressure) is proportional to 1/V (volume). Since density is mass/V, then P is directly proportional to density.

Now, air at sea level is 1/800 the density of water. And, pressure increases roughly one atmosphere for every 33 feet of depth.

So, air becomes as dense as water at a depth of 33x800=26400 feet.

Therefore, at five miles down, they ain't no hope of raising anything with bags or ping pong balls or anything else filled with air.

Is it possible to fill the bags or balls with a lighter-than-water incompressible fluid (e.g. gasoline or petrol)?

This is fun.


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Subject: RE: Can you really raise a ship with hot air
From: Amos
Date: 09 Sep 03 - 04:55 PM

Well if you force air into an area inside the hull its not hopeless, assuming the hull doesn't just crush.

At that depth I'd expect the hull to be riddled with holes by this time -- the Andre Doria hit the Stockholm in 1956, if memory serves...


A


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Subject: RE: Can you really raise a ship with hot air
From: Gareth
Date: 09 Sep 03 - 05:05 PM

Tia - Interesting mathematics regarding the depth where water and air densities are the same. But one minor nitpick - what percentage o the Ocean is below that depth.

The original Bathesphere (I hope I've got the name and spelling correct) used Gasoline as a float/bouyancy aid.

General point as per song The Mary Ellen Carter was alledgedly raised with the aid of compressed air - This point has been made in other threads.

The problem with attempting to raise the "Andrea Dorea" on compressed air might be fun, but overlooks the extent that corrosion will have weakened the hull and superstructure over 50 years, the need to close and dog all scuttles and vents, and the dirty great big hole the "Stokholm's" Ice Class Three bows made in her.

BTW do 'Catters realise tat the "Andrea Dorea/Stokholm" collision was the first recorded incident of the Radar assisted collision.

The problem with radar is it shows you where the other ship is, where it has been, but don't tell you what its going to to next !

Gareth


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Subject: RE: Can you really raise a ship with hot air
From: MudGuard
Date: 09 Sep 03 - 05:07 PM

deterioration of the hull?

Where is John from Hull when you need him?
He could borrow you his hamster, so you would have the necessary electricity for the pumps to pump the hot air into the hull...


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Subject: RE: Can you really raise a ship with hot air
From: Don Firth
Date: 09 Sep 03 - 05:36 PM

Back about nineteen-ought-eighty, somewhat before Robert Ballard actually located the Titanic, there was a novel written by Clive Cussler called Raise the Titanic!. The movie made from Cussler's novel, an attempt at a Hollywood blockbuster, turned out to be a real stinker and sank much more quickly than the Titanic itself did. I haven't read the book, nor did I see that movie, but I have read a few of Cussler's novels, and his technical details are generally pretty well thought out and often possible, or at least feasible. This thread got me curious about what method Cussler devised to do the job. Googling through cyberspace for this information didn't prove productive; there were brief reviews of the book and the movie, and much discussion of how imaginative (but cluttered with detail) the book was and how putrid the movie was and how great the musical score was despite the fetidness of the movie itself—but zero, naught, nuttin' about what I was really looking for. I assumed he probably did something like reinforce the hull integrity, then fill the ship with big balloons filled with air or some other gas (in a different medium, helium-filled balloons worked much too well for Lawn Chair Larry). If anyone has read the book, or seen the movie (and not repressed it), maybe they could explain Cussler's method.

In my perambulations through the ether, I did find this, however (lots of links at the bottom of the article).

Don Firth


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Subject: RE: Can you really raise a ship with hot air
From: MudGuard
Date: 09 Sep 03 - 05:45 PM

Don, I bought and read the book some years ago - but my memory fails...
And as I left the book behind in some youth hostel, I can't look it up...


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Subject: RE: Can you really raise a ship with hot air
From: Gareth
Date: 09 Sep 03 - 07:01 PM

Don - I read the book - CRAP ! Why it was publshed I do not understand.

Gareth


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Subject: RE: Can you really raise a ship with hot air
From: Amos
Date: 09 Sep 03 - 08:50 PM

Gareth:

Can you say "sales...."? SURE you can!! :>)


A


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Subject: RE: Can you really raise a ship with hot air
From: Nigel Parsons
Date: 10 Sep 03 - 03:22 AM

Tia:
According to the ideal gas law PV=nRT. Avogadro's n is a constant, and we can pretend that R and T are as well (to make it simple enough for me to handle). So, P (pressure) is proportional to 1/V (volume). Since density is mass/V, then P is directly proportional to density.
my 'A' level Physics (failed) is some 30+ years behind me, but as I recall it the required formula here is PV/K (pressure*volume/temperature) is constant thus as temperature falls as one goes down in the water, using the above, Pressure and density are not directly proportional.

Nigel


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Subject: RE: Can you really raise a ship with hot air
From: Don Firth
Date: 10 Sep 03 - 04:09 AM

Okay, that saves me reading it. Thanks.

Don Firth


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Subject: RE: Can you really raise a ship with hot air
From: Hrothgar
Date: 10 Sep 03 - 05:00 AM

If you could send the air down in rigid containers - like ping pong balls - that could themselves withstand the outside pressure, the air inside would retain its negative buoyancy at the required depth. The problem would be getting a container that did not weigh so much itself that the air's buoyancy raised only the container.

Of course, if you could find containers that strong, you could evacuate the air inside them and give them even more buoyancy.

Easier to leave the ship there, chaps.

p.s. Sir Lew Grade, whose company lost a motza on the "Raise the Titanic" movie, is reported to have said, "It would have been cheaper to lower the Atlantic!"


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Subject: RE: Can you really raise a ship with hot air
From: Dave Bryant
Date: 10 Sep 03 - 07:15 AM

I thought that Boyles (or was it one of Charles') law was:

The angle of the dangle is proportional to the heat of the meat, providing that the urge remains constant.

BTW Hot air can't provide such a vast amount of lift otherwise John from Hull would be up in the stratosphere by now !


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Subject: RE: Can you really raise a ship with hot air
From: InOBU
Date: 10 Sep 03 - 07:54 AM

Lawn Chair Larry!!!!!!!!!!!!!!????????????????????????

F$%K'S Sake! Don!!! Putting aside that this was a joke about the Golden Hind thread... I not only spent 11 years as a boat builder before my present occupation(!?)... but I have raised a sunken skipjack from the east river, with one other fellow, in mid winter, without a wet suit, by going aboard and unshakeling the throat halyard so we could use it to carreen the vessle in a slip using a car... the water was below freezing, and I also had to cast off lines so we could ease her up the slip to do this, interesting feeling, feeling your self in a race with the sense of dieing from the cold, your brain is telling your limbs to run at one speed but they respond ten times slower... not really an lawn chair event, unfortunately.

Here in downtown New York, there aren't that many lawns.... could use one, chair and all.

One day, I will take a day off, and I hope when the day comes, some one (Don?) will lend me a lawn and a chair!

Keep yer feet dry folkies...

(No offence taken or meant)

Lifeboat Larry


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Subject: RE: Can you really raise a ship with hot air
From: Mr Happy
Date: 10 Sep 03 - 08:12 AM

how many balloons would you need to be lifted a small height above ground, say a foot or so, & would it be possible to maintain this height?


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Subject: RE: Can you really raise a ship with hot air
From: TIA
Date: 10 Sep 03 - 09:29 AM

Nigel - in my little homework problem, I pretended T was constant. Of course, it probably won't be...it'll drop with depth, making the density of both water and air drop as well. If they drop at the same rate, my estimate may be correctish, if they don't, who knows....

Gareth - my guess is that a very small percentage of the ocean is deeper than five miles. Only the deepest trenches at island arcs (Marianas at 7 miles, etc.) make it that deep, and they are narrow and few.

wish this map had a true depth scale


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Subject: RE: Can you really raise a ship with hot air
From: Dave Bryant
Date: 10 Sep 03 - 10:31 AM

Mr Happy there is a true story about a chap who tried exactly that and ended up in an air lane because he overdid it. I would think that getting a near neutral trim might prove difficult and even a light breeze would impart a considerable horizontal velocity.


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Subject: RE: Can you really raise a ship with hot air
From: Amos
Date: 10 Sep 03 - 10:48 AM

I am sorry to correct you but check the Snopes site regarding the "true" nature of the lawnchair Larry story. 'T ain't so, Dave!

That does not mean it is not possible, Mister Happy, but you can do the math(s) yourself.

A


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Subject: RE: Can you really raise a ship with hot air
From: InOBU
Date: 10 Sep 03 - 01:02 PM

OH THAT LARRY!!! I get it, I remember now... thought that was a reference to arm chair sailors... PS Is there anything that MCatters don't take serriously??? Cheers Larry


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Subject: RE: Can you really raise a ship with hot air
From: Don Firth
Date: 10 Sep 03 - 02:59 PM

Sorry, Larry (InOBU, that is). I wasn't taking a shot at you, and I was hardly taking things all that seriously—although I'm sure that to back in 1982, to Larry Walters things got pretty serious very quickly.

Although the Lawn Chair Larry incident has all the earmarks of an urban legend, it actually did happen, but not necessarily the way some people tell it. It's such a good story that it got told a lot, and the "folk process" tended to take over. The guy got himself in hot water with the FAA and earned himself an Honorable Mention in the Darwin Awards (given to those who do something incredible stupid and kill themselves in the process, thereby ridding the human gene pool of another packet of "stoopid genes."). Larry didn't kill himself in the process (although, sadly, he managed that later, but intentionally), but if he had, they probably would have named him winner instead of just giving him an honorable mention.

Here's the story the Darwin Awards page has on the incident: OY.

And here's what Snopes says about it: VEY!

Don Firth

P.S: Sorry for the thread drift, but in a weird way, it seem to relate.


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Subject: RE: Can you really raise a ship with hot air
From: TIA
Date: 10 Sep 03 - 04:20 PM

Ooops, my typo - density will rise with dropping temperature


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Subject: RE: Can you really raise a ship with hot air
From: Chief Chaos
Date: 10 Sep 03 - 04:57 PM

The assist that the radar gave in the Stockholm / Andrea Dorea collision wasn't a matter of where the other ship would go. At the time there was no requirement for the radar system to have back lit (red, so as not to destroy watchstanders night vision) dials which would enable the operator to see at a glance what the settings were. According to the official report the operator thought the range from one ship to the other was actually greater than the other and commenced a turn across the others path. Once the turn began there was very little chance the other vessel could avoid the collision.
There are computer system radars called ARPA (Automated Radar Plotting Aids) which track other vessels and their positions as well as there predicted courses based on the objects apparent speed and course, relative to the course that the ARPA equipped vessel is on. It is a legal requirement for certain size vessels to be equipped.


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Subject: RE: Can you really raise a ship with hot air
From: Gareth
Date: 10 Sep 03 - 07:01 PM

Chief C - "Constant Bearing = Certain Crunch" - but as you say, the plot was misinterpreted - with tragic results.

Unfortunatley too great a trust in electronic navigational aids still goes on.

I once took a 20' sloop though the Narrows in the Swale/ with my crew member using my old rotating LED Echo Sounder and calling the depth.

Panic ! Until he got his head out of the hatch, and could see where we were. - one can to port, one cone to starbord, pistol shot either side. Panic over - We made the pub in Queenboro' befor shut tap.

Gareth


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Subject: RE: Can you really raise a ship with hot air
From: EBarnacle1
Date: 11 Sep 03 - 12:35 AM

Lawnchair Larry's exploit was anticipated by both Cyrano deBergerac and Baron Munchausen. Both of these heroes report having arrived on the moon by balloon prior to the 19th century. Of course, if the aether extends sufficiently into Space, our satellites would fall down due to friction...or is it all a fiction maintained by a vast international conspiracy?


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Subject: RE: Can you really raise a ship with hot air
From: MudGuard
Date: 11 Sep 03 - 02:09 AM

About the temperature dropping with depth:

If I remember correctly, quite close under the surface the temperature of roughly 4° Celsius is reached. From there on the temperature does NOT fall any further.

(at roughly 4°Celsius water has its smallest volume - that is why ice cubes are swimming in water...)


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Subject: RE: Can you really raise a ship with hot air
From: Don Firth
Date: 11 Sep 03 - 02:13 AM

I recall seeing a cartoon that was published just before the Apollo 10 moon shot. That was the one where they went around the moon, but didn't land. The cartoon showed the Apollo capsule going around the back of the moon. A couple of astronauts were rubbernecking out of a window and what they saw was a hollow hemisphere, obviously a wooden frame with a monstrous sheet of canvas stretched over it, and on part of the frame, it read "Act III, scene 2."

Don Firth


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Subject: RE: Can you really raise a ship with hot air
From: Teribus
Date: 11 Sep 03 - 03:20 AM

The trick with salvage, according to an old US Navy Salvage Master, is to get the water out and keep enough of it out to attain positive buoyancy - lots of ways to do that, provided the structure to be raised has the integral strength to withstand the forces required.

In the Mary Ellen Carter's case, "Thank God she's only sixty feet and the currents here are slow".

Cox and Danks raised the scuttled ships of the German High Seas Fleet from the bottom of Scapa Flow by cutting into the hulls and "winning" them back compartment by compartment. Cofferdams were attached to the hulls and built up in sections until the top of the coffer dam reached above the surface. The lowest section attached to the hull was an air lock. The book written about it, "The Man who bought a Navy" is a great read for those interested in that sort of thing.

On the radar assisted collision, even with the earliest radar sets (all relative plotting), three "paints" of any target will give you its actual range, relative course and relative speed from which its actual speed, actual course and CPA (closest point of approach) can be very easily calculated. As stated by Gareth above if those three "paints" show no indication of relative bearing change - unless you alter course/speed you are going to collide with that contact.


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Subject: RE: Can you really raise a ship with hot air
From: GUEST
Date: 11 Sep 03 - 12:34 PM

Larry,

Regards your original question.

Maybe.....

Don Meixner


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Subject: RE: Can you really raise a ship with hot air
From: Chief Chaos
Date: 11 Sep 03 - 04:49 PM

I learned about radar assisted collision my first time underway using a faulty set. The bearing was somehow skewed 90 degrees from actual course. Instead of heading upriver we were quickly headed for an allision with the end of a dock!

Chief Chaos definitions:
1. Illusion - when it looks like something is taking place that isn't.
2. Allision - When a underway (moving) object strikes a non-moving object (not a sandbar, bank, or otherwise natural part of the waterbody).
3. Collision - When two underway objects (vessels) strike each other.
4. Allusion/Collusion - When it looks like a moving object or two moving objects are about to hit each other (otherwise known as "time to clean the underware!)


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Subject: RE: Can you really raise a ship with hot air
From: Mr Happy
Date: 12 Sep 03 - 02:48 AM

by sheer coincidence, my own query about balloons need to raise a person, was answered by last nights 'science shack' programme on bbc2.

adam hart davies was propelling himself along with wimgs strapped to his arms, while suspended a few feet in the air by a very large, I'd estimate 10ft diameter, balloon.

drat!, i thought, that puts the kybosh on my brilliant new invention!


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Subject: RE: Can you really raise a ship with hot air
From: InOBU
Date: 12 Sep 03 - 03:19 PM

Hi Don! I think we proved the intitial question's point well enough... catch you all after another twenty pages... and see how far up the shi.... ...p is rising. Cheers Larry


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Subject: RE: Can you really raise a ship with hot air
From: Mr Happy
Date: 18 Sep 03 - 04:14 AM

Come Take a Trip in my Airship [George Evans and Ren Shields]
I once loved a sailor
Once a sailor loved me
But he was not a sailor who sailed on the wide blue sea
He sailed in an airship -- sailed like a bird on the wing --
and every Friday at midnight, he would come to my window and sing:

Chorus:
Come take a trip in my airship
Come sail away to the stars
We'll travel to Venus
We'll sail away to Mars

No one will see as we're kissing
No one will know as we swoon
So come take a trip in my airship,
and we'll visit the man in the moon

One night while sailing away from the crowds
we passed through the milky-white way
While idly drifting watching the clouds he asked if I'd name the day
Just by the dipper I gave him my heart
The sun shone on our honeymoon
We swore to each other we never would part, and to teach all the babies this tune

Chorus


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Subject: RE: Can you really raise a ship with hot air
From: The Fooles Troupe
Date: 18 Sep 03 - 06:04 AM

There is now a recent movie in which a guy has (helium) balooons tied to his lawn chair, takes off, lands somewhere, and has a new life. Have only seen the trailer on TV.

The story sems like what happened to the Wizard, in The Wizard of Oz... from his viewpoint... :-)

Robin


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Subject: RE: Can you really raise a ship with hot air
From: Gurney
Date: 18 Sep 03 - 06:20 AM

More ramblings.

I once saw a salvor disprove the ping-pong ball method on a TV programme. Even at wet-suit depth they crushed into cup-shapes and lost all boyancy.

I thought that a standard method was to use the tide:
Hitch one sunken vessel to two floating ones at low tide.
Drag the salvee through the water at high tide until it grounds.
Wait for the tide to fall, shorten the hitches, wait for the tide to rise..... have to be not too far to shore, among other requirements.


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Mudcat time: 22 September 6:05 AM EDT

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