Any reason why not?

Some icebreakers ride up over the top of the ice to crack it.

If it doesn’t crack, just keep going on top of the ice until it does crack, then continue as a ship again.

Why not?

Probably a bit hard to do. Needs a separate land/ice propulsion system. AFAIK they use water jets instead of propellers, but they are not much good if completely out of the water.

Also they tend to use sea water for engine cooling, also a bit of a problem if they are spending an extended time out of water.

It probably would be doable in some way shape or form engineering wise. But so far the absolute need for it had not arisen, nor the situation where it would be economically more advantageous to do it that way.

party_pants said:

Probably a bit hard to do. Needs a separate land/ice propulsion system. AFAIK they use water jets instead of propellers, but they are not much good if completely out of the water.

Also they tend to use sea water for engine cooling, also a bit of a problem if they are spending an extended time out of water.

It probably would be doable in some way shape or form engineering wise. But so far the absolute need for it had not arisen, nor the situation where it would be economically more advantageous to do it that way.

Ships get trapped in ice every year and need to call privately owned icebreakers to get them out. The economic cost due to delay plus calling an icebreaker plus cost of ice damage is really expensive, not unusal for a ship caught in ice to run at a loss.

Hadn’t thought that cooling when travelling on ice may be a problem, but you’re right. It might be.

mollwollfumble said:

Any reason why not?

Some icebreakers ride up over the top of the ice to crack it.

If it doesn’t crack, just keep going on top of the ice until it does crack, then continue as a ship again.

Why not?

They currently break thick ice by riding up on to the outer edge, at least then the ship is at the ice weakest point, plus the weight at the sharp end of the ship and its momentum, I would think would be more efficient than climbing onto the ice and spreading the weight of the ship.

mollwollfumble said:

party_pants said:

Probably a bit hard to do. Needs a separate land/ice propulsion system. AFAIK they use water jets instead of propellers, but they are not much good if completely out of the water.

Also they tend to use sea water for engine cooling, also a bit of a problem if they are spending an extended time out of water.

It probably would be doable in some way shape or form engineering wise. But so far the absolute need for it had not arisen, nor the situation where it would be economically more advantageous to do it that way.

Ships get trapped in ice every year and need to call privately owned icebreakers to get them out. The economic cost due to delay plus calling an icebreaker plus cost of ice damage is really expensive, not unusal for a ship caught in ice to run at a loss.

Hadn’t thought that cooling when travelling on ice may be a problem, but you’re right. It might be.

Rarely is the ice flat enough to travel on. Weather and tidal movement often forces ice upwards trapping it in ragged ridges.

PermeateFree said:

mollwollfumble said:

party_pants said:

Probably a bit hard to do. Needs a separate land/ice propulsion system. AFAIK they use water jets instead of propellers, but they are not much good if completely out of the water.

Also they tend to use sea water for engine cooling, also a bit of a problem if they are spending an extended time out of water.

It probably would be doable in some way shape or form engineering wise. But so far the absolute need for it had not arisen, nor the situation where it would be economically more advantageous to do it that way.

Ships get trapped in ice every year and need to call privately owned icebreakers to get them out. The economic cost due to delay plus calling an icebreaker plus cost of ice damage is really expensive, not unusal for a ship caught in ice to run at a loss.

Hadn’t thought that cooling when travelling on ice may be a problem, but you’re right. It might be.

Rarely is the ice flat enough to travel on. Weather and tidal movement often forces ice upwards trapping it in ragged ridges.

If ice is rarely flat enough to travel on, then why do we have a TV show called “ice road truckers”? But yes, i’m aware of pressure ridges. But they do tend to be only 3 or so metes high.

Yes it’s far more energy climbing out on ice than cracking it. But not as much energy as repeatedly ramming it and failing to make headway.

I suspect one big argument against using amphibious vehicles would be seasonal variation. They would only be most efficient at times of freeze and thaw, for perhaps only one month a year, no more than two months a year.

And there would be the extra weight and either width or water drag generated by the amphibious tracks.

mollwollfumble said:

PermeateFree said:

mollwollfumble said:

Ships get trapped in ice every year and need to call privately owned icebreakers to get them out. The economic cost due to delay plus calling an icebreaker plus cost of ice damage is really expensive, not unusal for a ship caught in ice to run at a loss.

Hadn’t thought that cooling when travelling on ice may be a problem, but you’re right. It might be.

Rarely is the ice flat enough to travel on. Weather and tidal movement often forces ice upwards trapping it in ragged ridges.

If ice is rarely flat enough to travel on, then why do we have a TV show called “ice road truckers”? But yes, i’m aware of pressure ridges. But they do tend to be only 3 or so metes high.

Yes it’s far more energy climbing out on ice than cracking it. But not as much energy as repeatedly ramming it and failing to make headway.

I suspect one big argument against using amphibious vehicles would be seasonal variation. They would only be most efficient at times of freeze and thaw, for perhaps only one month a year, no more than two months a year.

And there would be the extra weight and either width or water drag generated by the amphibious tracks.

Ice Road Truckers from the few episodes I have seen operate on freshwater lakes, which obviously would not be subject to the tides and currents leading to compaction and upheaval generated from moving sea ice.

PermeateFree said:

Ice Road Truckers from the few episodes I have seen operate on freshwater lakes, which obviously would not be subject to the tides and currents leading to compaction and upheaval generated from moving sea ice.

Yah. I see the point. Freshwater lakes and rivers (eg. Alaskan rivers). You do occasionally need icebreakers on freshwater lakes, such as the US Great Lakes, but it’s nowhere near as harsh an environment as open ocean.

I had been wondering how to operate the propulsion system on land, thinking of vehicles like those that operate in Antarctica, tyres or caterpillar tracks. Thinking of amphibious army vehicles that resemble army tanks, with an unacceptably huge drag in the water.

And then it occurred to me that I was going about this the wrong way around. Think snowmobile. These travel on skis and most importantly get their propulsion from a gear wheel that bites into the ice. So the icebreaker under the water becomes something like a trimaran, a central knife cuts through and breaks the ice and acts as a central ski further back from the bow. The outer parts of the trimaran are the main skis. At high enough speeds in water these three skis would actually act as hydrofoils, (if designed to go that fast).

Instead of a single gearwheel that bites into the ice, have two. The main thrusters for the ship operation are avipods, propellers capable of being rotated 90 degrees for tight maneuvering. These are standard on many large ships. Rotate these propellers 90 degrees and reverse the rotation direction of one of them and they become like the gear wheel that propels a snowmobile.

The propellers and avipods need to be hugely strengthened, with roughened edges to bit into the ice, and geared down to lower speeds for travelling on ice. Steering on land would be largely by changing the relative speeds of the two avipods.

There are three big advantages of this design. One is that it will all fit in a rectangle that will still fit through locks without loss of capacity, it utilises otherwise unused space in the corners for the trimaran-skis. A second is that you don’t lose significant fuel through increased water drag. A third is that you actually improve watergoing stability with the outriggers, and these have the potential for increasing travel speed on water as well.

party_pants said:

Probably a bit hard to do. Needs a separate land/ice propulsion system. AFAIK they use water jets instead of propellers, but they are not much good if completely out of the water.

Also they tend to use sea water for engine cooling, also a bit of a problem if they are spending an extended time out of water.

It probably would be doable in some way shape or form engineering wise. But so far the absolute need for it had not arisen, nor the situation where it would be economically more advantageous to do it that way.

The problem of water cooling for the engines still remains, would require some engineering innovation such as a more efficient heat exchanger and an engine oil that is more tolerant of high temperatures.