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Flash
3681.  Sat Dec 27, 2003 12:28 pm Reply with quote

Q: Why might you hold your breath on a submarine?

A #1: Submarines are unable to send or receive radio communications whilst submerged, so they surface once a day to contact base. Whilst on the surface, an officer is sent out to stand in the conning tower and keep watch. The conning tower is the only bit of the vessel which is out of the water, so this guy is basically standing in a dustbin in the middle of the ocean with absolutely nothing but water visible in all directions - a fairly weird experience, I would think. Now, if a big wave comes along, it gets weirder still, because the wave's going to go right over this guy's head and he will in fact be completely submerged, standing on top of the submarine - and he has to hold his breath until the wave passes. He's harnessed in so he doesn't get washed away, but if it's a really big wave and he runs out of puff then all he can do is release the harness and pop up to the surface like a cork, and hope that someone notices he's missing before the sub dives again.

A #2: The ambient smell on a submarine is basically essence of thrice-unwashed sock, and the only person who is exposed to any other smell is the guy in the previous answer. The others all become acclimatised, to the point that when they get their first lungful of fresh air after months at sea it smells rank and makes them retch. So, submariners emerging from the vessel for the first time hold their breath until they're somewhere suitable for throwing up.

Forfeit: "when you're escaping from a sinking sub". The one time you shouldn't hold your breath is when you are ascending from deep water, because the air expands as the pressure decreases and can burst your lungs. In fact, in a fast ascent you have to breathe out quite hard just to maintain a constant volume in your lungs (if you are breathing in whilst under pressure, that is - eg with scuba equipment).

s: conversation with Commander Arnie Lustman RN, a former submariner

 
JumpingJack
4079.  Sat Jan 10, 2004 8:50 pm Reply with quote

Very QI, Flash.

Enjoyed that a lot.

 
Jenny
4087.  Sat Jan 10, 2004 9:36 pm Reply with quote

The first American submarine was David Bushnell’s Turtle, built in 1775. It was powered by a hand-driven propellor, and normally floated with about six inches of exposed surface. It was intended to break the British naval blockade of New York harbour during the American Revolution. The operator would submerge under the target by flooding water into the craft until it started to sink, although this unfortunately left the operator knee-deep in water. He would then use a screw projecting from the top of the submarine to attach a delayed-action explosive charge detonated by a clock. He used a hand pump to remove the water from the submarine to enable it to resurface.

http://tinyurl.com/2b9g2

Sorry - corrected the link now so the page formatting isn't screwed up. The site is 'How Stuff Works'.


Last edited by Jenny on Sun Jan 11, 2004 10:02 am; edited 1 time in total

 
hardie
4108.  Sun Jan 11, 2004 7:35 am Reply with quote

During the Cold War Polaris submarines would spend months at a time on the sea floor in the Arctic literally inching forward to test Soviet defence systems. The subs submerged on leaving the Clyde and would only surface again when they got back. Only two officers were alllowed to know their destination. The incidents of mental health problems almost always occured during the first or last days of the voyage.
Source: a cousin of the wife who was at the time a Polaris officer ....

 
Flash
4158.  Sun Jan 11, 2004 6:50 pm Reply with quote

Soviet submarines used to have a naval commander on board but also a political commissar whose responsibility was directly back to the political authorities in Moscow. The commissar's bunk was in the radio room, an armoured chamber which had the only lockable door on the vessel, the idea being that if there was a mutiny or attempt to defect he could barricade himself in and hold out against the crew.

Psychologically an interesting situation to be in - living literally cheek by jowl with the crew for weeks on end, whilst all the time they and you both know that your only function there is to keep tabs on them and report on their conduct to the authorities.

s: my visit to a Soviet submarine docked in Folkestone harbour as a tourist attraction.

 
Frederick The Monk
4768.  Sun Jan 18, 2004 7:46 am Reply with quote

Unusual Boats
(prompted by some saints stories)

St. Pirrin floated from Ireland to Cornwall on a millstone
St. Bega came across the Irish Sea to Cumberland on a clod of earth
St Ia reached Cornwall on a leaf (and had St. Ives names after her)
St. Francis of Paola crossed the straits of Messina on his cloak (Franz Liszt commemorated this in his "St. Francis of Paola Walking on the Waters"

s:http://www.sheetmusicarchive.netdlpage_new.cfm?composition_id=1827
http://www.catholic-forum.com/saints/indexsnt.htm

 
DELETED
4789.  Sun Jan 18, 2004 12:51 pm Reply with quote

DELETED

 
Stapes
6060.  Tue Feb 17, 2004 10:44 am Reply with quote

In 1943 the SS Schenectady sunk, at only 1 day old, having just returned to harbour after sea trials. The cause of its demise was a tiny crack, which ended up splitting the vessel in 2. In 1928 the White Star Liner Majestic was saved from a similar fate by a porthole.

When a crack starts, all of the stress is concentrated at the sharp tip of the crack (like when someone stands on your foot with a stiletto heel, it hurts). If there is enough pressure to start a crack, there's enough pressure to finish the job and crack something completely in half. As the crack can only progress if the tip remains sharp, you can stop a crack by blunting its point, which then dissipates the pressure and therefore the progress of the crack.

"Crack stoppers" are any soft components in a composite material - that's why specific materials and combinations of materials are needed to eg. build a jet engine, a bridge, or even a biscuit. The crack stoppers in a biscuit are sugar, starch and fat. The best crack stopper on a biscuit is a coating of chocolate (this has been scientifically proven with dunking experiments).

Any rounded corner also stops, or at least slows a crack, as the sharpness of the crack is blunted so the pressure dissipates. The ultimate crack stopper is an actual hole - the Shenectady sunk while the Majestic was saved because the crack in the Majestic hit a porthole.

S: How to dunk doughnut - Len Fisher

 
Jenny
6061.  Tue Feb 17, 2004 11:22 am Reply with quote

There's got to be a question in that somewhere, even if it's only about dunking biscuits. There's an article on the net by Len Fisher, about dunking: http://www.firstscience.com/site/articles/dunking.asp

Q At what angle would you have to dunk a biscuit into your tea to make it less likely to collapse and fill your teacup with soggy biscuit crumbs?

A Hold it with the flat surface parallel to the tea rather than at 90 degrees, as long as you don't mind burning your fingers on the hot tea.

We could go in further detail into the Washburn equation if necessary - there's a rather nice analogy Fisher makes about the length of time a drunken man takes to stagger back from the pub.

 
Flash
6078.  Tue Feb 17, 2004 7:02 pm Reply with quote

Agreed.

In Australia you can get a biscuit called a TamTam which is sort of like a Penguin. They bite two pieces off opposite corners, then dip one end in their tea and suck the tea up through the wafers, like a straw. Then they eat the tea-impregnated biscuit. Excellent, I imagine. Dan?

 
Stapes
6086.  Wed Feb 18, 2004 6:32 am Reply with quote

For further info on dunking, the first chapter of How to Dunk a Doughnut goes into it in huge detail, including biscuit thinness, brittleness, angle of dunk, time of dunk, hot liquids, cold liquids - there didn't seem space to go into it, but I will if we're going to have a question on it. Standing by.

 
Jenny
6194.  Sat Feb 21, 2004 10:28 pm Reply with quote

To wrench the subject back to boats - or rather, ships - my husband presented me with a nice little snippet today and suggested I post it here. However, be warned, I have not fact-checked this:

Quote:
The U.S.S. Constitution (Old Ironsides) as a combat vessel carried 48,600 gallons of fresh water for her crew of 475 officers and men.

This was sufficient to last six months of sustained operations at sea.

She carried no evaporators (fresh water distillers).

However, let it be noted that according to her log, "On July 27, 1798, the U.S.S. Constitution sailed from Boston with a full complement of 475 officers and men, 48,600 gallons of fresh water, 7,400 cannon shot, 11,600 pounds of black powder and 79,400 gallons of rum."

Her mission: "To destroy and harass English shipping."

Making Jamaica on 6 October, she took on 826 pounds of flour and 68,300
gallons of rum.

Then she headed for the Azores, arriving there 12 November. She provisioned with 550 pounds of beef and 64,300 gallons of Portuguese wine.

On 18 November, she set sail for England.

In the ensuing days she defeated five British men-of-war and captured and scuttled 12 English merchantmen, salvaging only the rum aboard each.

By 26 January, her powder and shot were exhausted.

Nevertheless, and though unarmed, she made a night raid up the Firth of Clyde in Scotland.

Her landing party captured a whiskey distillery and transferred 40,000 gallons of single malt Scotch aboard by dawn.

Then she headed home.

The U.S.S. Constitution arrived in Boston on 20 February 1799, with no
cannon shot, no food, no powder, NO rum, NO wine, NO whiskey and 38,600
gallons of stagnant water.

 
Flash
6195.  Sun Feb 22, 2004 7:50 am Reply with quote

Very nice. Is the implication meant to be simply that they drunk it all, do you think? ie is this the story of the mother of all pub crawls, or is there something more interesting going on?

 
Jenny
6198.  Sun Feb 22, 2004 11:00 am Reply with quote

The bits I didn't post said things like 'Now there were men who knew how to drink - GO NAVY!' so I think the implication was that they drank it all.

 
megra
559937.  Tue May 26, 2009 6:54 am Reply with quote

Contrary to what was said on QI, I was told by an RN officer I knew some years ago that nuclear submarines are ships and all other submarines are boats. Just because he was in the RN doesn't mean he was right of course so could the elves check this.

 

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