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Post by trbixler on Jan 15, 2012 14:47:32 GMT
Back to the story. "Tanker makes final preparations for tricky fuel transfer in Alaska" A Russian tanker with a cargo of much-needed fuel for Nome was moored less than a half mile from the Alaska town's iced-in harbor Sunday morning, holding for disturbed ice to refreeze before crews can finish work to deliver the fuel, the Coast Guard said. The U.S Coast Guard Cutter Healy, which cleared a path through hundreds of miles of Bering Sea ice for the tanker, was nearby. "We were able to successfully navigate that last bit of ice," Coast Guard spokesman Kip Wadlow said. "We were able to get it pretty much right on the money, in the position that the industry representatives wanted to start the fuel transfer process." www.foxnews.com/us/2012/01/14/tricky-transfer-awaits-tanker-in-alaska/#ixzz1jXRC8JkBmore pics and stuff abcnews.go.com/US/wireStory/tricky-transfer-awaits-tanker-inching-alaska-15360333#.TxLndnpv-e0
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Post by numerouno on Jan 16, 2012 13:36:49 GMT
Numerouno began by saying boats do not ram ice. He is now saying that ramming ice as a description of what the Urho class of boats is doing when moving slowly forwards as shown in the video is dishonest or at least misleadingYes I did, and I won't be changing what I said. These boats do not "ram" anything. They do not have any structures that are designed to receive or give strong blows in the horizontal direction. You might as wll argue that when a surgeon is opening your skin, he or she is "ramming" the skin with his or her knife, or that a pair of scissors is "ramming" the paper. The icebreaker is not a blunt instrument. If a surgeon needs to say, cut through a layer of fat in a patients abdomen, he or she will have to make several incisions, each one deeper in the tissue than the previous one. This is not "ramming" either. I would have to say what we have here is the difference between a verb and a nounIcefisher, did you notice I posted pictures of what "ajo-oja", the actual term used, means according to a google search. "Trenching": www.propertysolutions.me.uk/trench.htm"avo-oja" www.ymparisto.fi/default.asp?contentid=181882&lan=fi(Official instructions on how to build a private sewage treatment plant)
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Post by numerouno on Jan 16, 2012 14:59:08 GMT
And i can tell you that here in Helsinki if you place your finger hard against solid ice at -19C it burns your finger without showing any visible signs of melting.
You did not mention you're a living dead ... it's getting sort of scary.
If you are alive, on the other hand, by all means take the ice into your hand. I could record it for you on the video, since you come from other parts and your hands are tender.
Since you know how to translate Finnish into English, how would you translate "avo-oja"? Just curious.
So your science is IT science? And you're bloody stubborn? Welcome to Finland then!
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Post by numerouno on Jan 16, 2012 17:09:35 GMT
Iceskaters, let's work the basic physics a bit shall we?
Take undisturbed mature ice (sea or freshwater):
The bottom of the ice is at what temperature? The top of the ice is at what temperature?
Any Gnomes inside the ice working their mysterious cooling system to any wildly cold temperature, as you seem to suggest?
You're perfectly free to call anyone. If you need to call "an expert", what originally made you think you're an expert in translating Finnish? This is a difficult language, they say.
I don't think I saw your proposing a translation to "avo-oja" into English? Is there one forthcoming in the near future? How many "sides" do you see in the "avo-oja" I posted? Two, three, more?
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Post by numerouno on Jan 16, 2012 19:41:25 GMT
Iceskaters, I don't think I've seen your (or your wife's) English translation of "avo-oja"? Can I have it now please? Sorry if you've posted it before, I just can't seem to be able to find it.
What would you be calling the formation in my picture of "avo-oja"? Would it be totally out of place to call it a trench? Also when the British (picture posted above) were "trenching", what they actually appeared to have been creating, in the picture?
Iceskaters as well, I just put my finger against the frozen freezer wall (about -20C) wall. After some 15-20 seconds, I did not have the tip of my finger fall off, but felt my finger was starting to glide against the ice. That is a sign of some water having formed. Where would it have originated from? I suggest melting. How about you? (Advanced question: what physical property of ice and snow does greatly contribute to [persons on] skis gliding on the surface of snow or ice?)
Btw, you've listed yourself as "female". Are there two "Ms Iceskaters" in total? Not that I would mind, but just asking.
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Post by numerouno on Jan 16, 2012 20:58:53 GMT
Iceskaters, are you possibly high on something (legal) You seem to be making less and less sense as the day's drawing to an end. You've got my winter sports mystery to solve still: why do [people on] skis glide fast and swift on snow and ice?
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Post by numerouno on Jan 16, 2012 21:06:44 GMT
You've got my winter sports mystery to solve still: why do [people on] skis glide fast and swift on snow and ice?
And the translation from your spouse for "avo-oja"?
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Post by trbixler on Jan 17, 2012 5:19:44 GMT
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Post by numerouno on Jan 17, 2012 21:16:38 GMT
You said your question about water under skis was advanced, but i did not think it worth answering
Are you planning to ski while in Finland? Or slip and fall in the streets? Then you should know more about the ice & snow physics basics, if it suits your inquisitive mind.
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Post by numerouno on Jan 17, 2012 21:50:05 GMT
Yes, Water. Water contributes greatly to making the skis glide. It's coming from the friction-induced heat between the skier and snow/ice.
Your icebreker never actually leaves water when on ice, only the scale changes.
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Post by sigurdur on Jan 18, 2012 1:36:30 GMT
LOL......I knew where this was going a number of posts ago.
I am sure the film of water under the hull of the ice breaker provides enough continuous fluid mass so that the propellers can keep that mights surge forward alive.
Something tells me that ice chunks, while quite heavy to move, cavitate when used as resistance to drive the ice breaker through the ice.
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Post by trbixler on Jan 18, 2012 13:30:45 GMT
Not to slide into this discussion but here is some info. There are some formulas in the pdf but they do not reproduce well here. "The modern description of surface melting is that “the surface of a solid, at uniform temperature, develops a thin layer of its melt at temperature below the bulk transition temperature” (Wettlaufer, 1999b) (Fig. 3). The layer is a precursor of the complete melting of the solid and influences adhesion, crystal growth and other behaviour of the material (Wettlaufer, 1999a). Molecular solids, like ice as well as other materials, undergo the process of surface melting. It begins well below the melting point of the material and gradually thickens with rising temperature. At start, the layer is a few molecules thick and at the melting point the layer diverges. As outlined by Wettlaufer (1999a), surface melting is a special case of wetting, where the intra fluid forces (cohesive forces) are weaker than the adhesive forces of the substrate (the solid). This pre-melted layer probably is an important factor, reducing friction at lower temperatures. Because of the non-nucleation barrier during melting, this effect is valid over a wide temperature range, whereas if it would have been a nucleation barrier, the temperature range for the influence would have been much narrower. The phenomenon of surface melting on a microscopic scale has impact on several macroscopic processes such as slipperiness of ice, facilitates sintering of snow, thundercloud electrification and frost heave (Dash and others, 1995; Wettlaufer and Dash, 2000). The thickness of the liquid like layer is between ~50 monomolecular layers close to 0°C and reduces to ~3 monolayers (the thickness of a H2O molecule) around -10°C. Other important material properties for the slipperiness of ice is the low shear strength and the relative high values of hardness, even close to its melting point" www.swixsport.com/dav/babc49f803.pdf
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Post by numerouno on Jan 18, 2012 13:50:06 GMT
Sigurdur, thanks for your contribution, however, ice blocks don't cavitate, it's the propellers that cavitate. Practical example of cavitation is the m/s Finnjet that was able to exceed 33kts: (The ship had both turbines and later conventional engines installed.) 1. VIBRATIONS
1.1. Where do the vibrations come from?
Everybody who has been on board the FINNJET knows about the Vibrations. But almost nobody really knows how these occur! Have they got to do something with the turbines? Or is it the shallow water effect? Neither nor!! Ex. Cruise Manager Steen Lolck Burnaes has given me a good explaination lately and here it is: The real reason for the vibrations on board the ship are so called cavitations!
"Cavitation is the forming of gas bubbles in liquids at low pressure. The boiling point of water depends on the pressure. The higher the pressure, the higher the boiling point (see "Fast Cooking pot") and conversely. At low pressure the boiling point of e.g. water can even reach a temperature which is lower than the actual temperature of the water. This means a spontaneous forming of gas bubbles. While pressure increases, these bubbles implode (decay) again, while generating a small bang. At ship screws cavitation is a destructive factor. On the one hand side it decreases overall efficiency, on the other side it produces damages, because of the temporary high pressures and temperatures which occur during the implosion of the gas bubbles. Up to now, no material is steady enough to resist these forces for a long period" (Wikipedia)
For Finnjet this means, that the continuosely changing pressure relations because of the gas bubbles make the screws vibrate. The long axles bigger the effect even more and transform the vibrations to the whole ship. Depending on Speed and propeller setting the vibrations have different strengths in different parts of the ship; the different speeds and vibrations are known very well! It is also made use of this fact, so that the vibrations can be always moved where they disturb the least. Still, the influence they have is small and it is surely not possible to transfer all vibrations from the back to the front. The reason why FINNJET shows so much stronger vibrations than other ferries can be found in the long screw axles as well as in the lack of know-how about cavitation in 1977. Also the speed plays a role. But why does it not vibrate on Superfast's ships then? Simply because the ships' hull and screw axles were designed with the computer and because the yards have learned from the experiences made on board ships such as FINNJET!www.finnjetweb.com/en/fakten/FAQ.htm
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Post by icefisher on Jan 18, 2012 17:19:21 GMT
Not to slide into this discussion but here is some info. There are some formulas in the pdf but they do not reproduce well here. "The modern description of surface melting is that “the surface of a solid, at uniform temperature, develops a thin layer of its melt at temperature below the bulk transition temperature” (Wettlaufer, 1999b) (Fig. 3). The layer is a precursor of the complete melting of the solid and influences adhesion, crystal growth and other behaviour of the material (Wettlaufer, 1999a). Molecular solids, like ice as well as other materials, undergo the process of surface melting. It begins well below the melting point of the material and gradually thickens with rising temperature. At start, the layer is a few molecules thick and at the melting point the layer diverges. As outlined by Wettlaufer (1999a), surface melting is a special case of wetting, where the intra fluid forces (cohesive forces) are weaker than the adhesive forces of the substrate (the solid). This pre-melted layer probably is an important factor, reducing friction at lower temperatures. Because of the non-nucleation barrier during melting, this effect is valid over a wide temperature range, whereas if it would have been a nucleation barrier, the temperature range for the influence would have been much narrower. The phenomenon of surface melting on a microscopic scale has impact on several macroscopic processes such as slipperiness of ice, facilitates sintering of snow, thundercloud electrification and frost heave (Dash and others, 1995; Wettlaufer and Dash, 2000). The thickness of the liquid like layer is between ~50 monomolecular layers close to 0°C and reduces to ~3 monolayers (the thickness of a H2O molecule) around -10°C. Other important material properties for the slipperiness of ice is the low shear strength and the relative high values of hardness, even close to its melting point" www.swixsport.com/dav/babc49f803.pdfgood job trbixler! So there is low temperature ice! And a whole internet page was wasted by somebody trying to claim there wasn't. Good thing you found it before SolarHam ran out of harddrive space! So the phase change melting process starts some 10C below the melting point!
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Post by numerouno on Jan 18, 2012 21:09:44 GMT
Hold you horses, Icefisher. The catch is "on surface only" and "all solid materials".
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