Icebreaker Healey escorting Fuel tanker to Nome.

[numerouno]

If these are not facts, then there's been some blatant lies publicly available (and broadcasted) by the national broadcasting company on one of the flagship's of the nation's shipbuilding industry, which as I told has built some 60% of the world's present icebreaker fleet.

It's healthy to be critical, but in the scientific method is also included the ability and necessity to admit when one has been shown to be wrong.

[sigurdur]

iceskaters:
I don't know if most people think that numerouno has a personality disorder, as much as he belives strongly in AGW.
He is an interesting contributor to this forum.

[glennkoks]

"I don't know if most people think that numerouno has a personality disorder, as much as he belives strongly in AGW. He is an interesting contributor to this forum." - sigurdur.

He certainly is an interesting contributor. Clearly very intelligent. However, I think he is in the same mold as astromet and their is no point in trying to argue with him.

I could be totally off base on this but I get the feeling numerouno would argue the very definition of a trench, tell you the proper dimensions and how to dig one but yet has never picked up a shovel and dug one himself. Probably comes from a wealthy family, has been very well educated but has never had to work a day in his life.

I apologize in advance if I am off the mark on this one.

[glennkoks]

The above entry should say there instead of their. And when I mean "work" I mean the manual type of labor. Righty tighty, lefty loosey, gloves on manual type of work.

[numerouno]

However, I think he is in the same mold as astromet and their is no point in trying to argue with him.

No, especially not with false arguments. But, thank you for you compliment.

Mr Astrowet is a hoax.

The first video says that Sisu can penetrate ice that is 14 meter thick below the water line. Why the limitation if it can go thru any ice?


Iceskaters, I think the answer lies in the definition of "any" meaning "any [first year] pack ice in the Baltic" vs "any ice anywhere", where pack ice of a multi-year origin would be encountered. EDIT: a lot clearly would depend on the flexibility of ice when the weight of the icebreaker is resting on it.

Certainly interesting to see if you could refute the findings of the yard's own research.

[numerouno]

At this stage it appears to be maingly how we interpret what is being told to us rather than necessarily refuting it.

Hhm, I think you were developing an antithesis of: "icebreakers of the Urho class are indicated to be able to "dig" a path into [Baltic] ice that is deeper than their own depth." Your mini-research goal is to show they can't. If you really do not have anything to refute, you could as well quit right away then. If you can't trust other peoples' research, you'll need to set up your own shop!

Some background: the specifications you've found consider the multipurpose icebreaker. As winters have become relatively milder in the Baltic, heavy single-purpose icebreakers such as the Urho class have been becoming more uneconomical to operate. Therefore, there's a need to develop multipurpose vessels that are able to be hired by contractors as e.g. cable laying and oil drilling support ships during the summer. These vessels will have different specifications regarding their duties as a conventional icebreaker. For breaking up the remaining thick ice in the Baltic, the Urho class is scheduled to remain in operation well into the 2020s.

[numerouno]

Fyi, you've misspelled the Urho class as "Urhu" three times now. I normally don't mind, I mistype things myself all teh time.

"Path" you can interpret any way you may want to.

The 2020s come from the YLE introduction to the video, and apparently refer to the design life of those 1970s' vessels. Rebuilding would extend the useful life, but then there's the question of whether there is anything left to break in the Baltic at that time.

[numerouno]

Belief is not a scientific concept, which you should know. You're welcome to show the YLE documentary and the yard are wrong, and support it with other evidence than your personal first reaction.

[numerouno]

The first thing he said was that these boats could not work in very thick ice. I then asked him if the boats could drill thru ice and he said they could.

Which incidentally negates the "ramming" you presented as the
mechanism of breaking up the ice under difficult conditions. The reversing to me appears to serve a similar purpose that you are applying to removing the residues when you're drilling a hole in the wall at home.
As I said, the primary factor is the weight of the ship.

I thank you for your efforts in clarifying this. It could be the YLE documentary was based on research situations that were not encountered in real life situations that Capt Valtari has worked in, though, as he seemed to be unsure on whether this was an outright impossible scenario. One would need to have an access to the original Wärtsilä research documents.

[glennkoks]

numerouno, you are welcome! These boards would not be the same without you and I certainly value your contrary opinion even if I do not agree 100%.

Was I wrong about coming from a wealthy family, and never having to do manual labor?

[numerouno]

Iceskaters, the forward momentum is close to 0 (in relative terms) in the situation we're discussing. There will be no need to "ram", as I understand the term. Its use here is if not totally at least greatly misleading.

I wonder if you gave the link to the YLE video to Capt Valtari? I also would tend to agree the captains of the major Finnish icebreakers would be closer to their 60th than 40th birthday. Thinking of it, in his post there might have been no need for him to have served on an icebreaker at all, given the changing circumstances of the now fully commercial (at least in theory) operations.

There could be a solution to the problem I hit upon when clearing snow from our yard for the bookmobile, not your typical household chore, but happens with us. The "ice under keel" scenario is to me much too conspicuously presented to be a simple mistake. I think it can happen, but, with a limitation. Unless there are enough cracks for water to emerge sufficiently in the opened channel, the bow propellers will suffer from what is know as cavitation, and their effectivity will drop dramatically right away. The use of the air bubblers (likely I'd think) would only serve to aggravate the situation.

Am I btw correct in assuming that your science is CS? That would explain one or two things I think could be rectified on your practical ice and show physics.

[icefisher]

In answering he did not discuss heeling at all. Potentially he has never heard of it. However he was clear that the boat cannot tunnel thru ice to create a canal and was authoritative in his responses.


The confusion is in the language. "Trenching" or like "digging a trench" is different than "a trench".

When one uses a spade shovel to dig a hole the shoveling gets more tiring if you just dig in one spot. The friction on the sides of the shovel exhaust your effort so you soon learn to cleam up the sides of the hole, like you do when you dig a trench. A posthole digger operates on that premise with the two blades vertical it cleans the hole as you go.

So this heeling operation is really like cleaning the sides of the hole. By propeller the vessel slides up on the ice and when it loses its ahead steam it stops with broken ice on both sides of the vessel pressing against the sides of the ship helping support it.

The heeling action shifts the weight of the vessel onto one side of the ice, allowing the ice on the other side to collapse back into the hole. When the vessel shifts back the other way its now ontop of broken ice (instead of having its edges pressing hard against the side of the vessel backed by the ice sheet behind it.

So really all its doing is breaking up some of the physics (leverage and friction) that the ice sort of chaotically creates from a simple forward attack on it.

And going back to the shovel analogy. You can dig the hole by persevering straight ahead in one spot (the vessel backing up and attacking in one direction) but there is an energy and time economy by adding the additional action of side cleaning the hole.

Thus it is like trenching where the sides are cleaned as you go but its not actually a trench. In fact, when faced with thick ice that stops the vessel the nose of the vessel is in a trench more frontal attacks on that trench has a lot of physics working against you not the least of which is the nose of the vessel is missing the ideal point of attack by riding up on the ice.

I would have to say what we have here is the difference between a verb and a noun. Or butting your head against a stone wall repeatedly and not thinking of imaginative ways to change the physics of the game.

[numerouno]

if you place very cold material of similar heat capacity to water

Ice is sitting there already, and has the ambient temperature. Some of it will be close to the temperature of the water, some of the air, and anything in between. It's an insulating material between the two. The practical "coldness" of it on your hand, for instance, is due to the phase change energy of ice, i.e. melting. I said this as you mentioned "low temperature ice" above.

[sigurdur]

I know nothing about how ice breakers operate. Interesting perspectives.
Thank you numerouno and iceskater.

[icefisher]

We can progress the research. These icebreakers do "ram" ice. If they are travelling thru ice at 14kts that is thin they can deal with thicker ice using the momentum of the boat. Baltic class has to be able to deal with 16m of ice at 13kts. An icebreaker that cannot 'ram' ice at speed is at risk of severe frontal damage. Ramming appears to be the technical term used to convert momentum to ice breaking using normal ice breaking action.

I agree. Ramming as a word is far broader than what nonum wants to limit it to. In war or in an accident when a large strong ship rams a smaller less strong ship the lesser vessel goes "under the keel" of the greater vessel. However, when the ramming ship rams a near equal or greater ship you frequently end up with two wrecked ships.

In war the 2 wrecked ship outcome is only chosen when you are trying to protect something else from the other ship.

Thus ramming must be done with discretion and with enough knowledge that what is rammed goes under the keel. "under the keel" ice is in effect successfully rammed ice even if a heeling manuever is required to disengage the ice to under the keel.

For ice a ship only needs to 10% of the mass of the ice to submerge it under the keel (if it can get on top of it). Obviously thick sheet ice can greatly exceed 10 times the mass of the ship. But ice is brittle so the mass of the entire sheet may not come into play.

One of the links above shows a ship heeling and breaking through the ice. It tilts the first way with little breakthrough but when it rolls back thats when it drops a lot.

If it were trenching the ice you would not see the bigger drop which is caused by the ice breaking and going sub keel. If it were a trenching action you would get approximate the same drop each roll as the ice grinds away. Short of finding out they outfit the chines of the vessel with a cutting edge I rather strongly don't think thats what the heeling is for.

That of course does not mean trenching is impossible but I would like to see a bit more evidence of it as opposed to just a nonum translation of what he thinks a word means. I believe the heeling is for the purpose I described it. When trying to pull a stake out of the ground when you can't just pull it straight is to rock it back and forth to clear friction away from the stake.