Rate of Bog

[752ndTank]

Bogging means just that either in soft sand mud etc... and while trying to get out you can become imobile ie throw a track etc

Mud was a real problem for armor in Italy, especially during the rainy months in the spring and fall. Sherman tanks had relatively short and narrow tracks, and the relatively small "footprint" created a high ground pressure. This left Shermans prone to sinking into soft ground. In the winter, the ground would go through freeze-thaw cycles, with the tank sinking deeper and deeper into the ground as the cycles progressed.

This problem was alleviated to some extent by the introduction of "duckbill" track extenders (also called "floats"), which added more surface area to reduce ground pressure.

To see a photo of a Sherman that is bogged down in Italy, see the second photo on the following web page:

Bogged Sherman in Italy

Hope this helps.

752nd Tank Battalion in WWII

[tar]

Well, in my previous test, I found the numbers somewhat close, but with an edge to the fast or hunt moving. This was based on admittedly limited numbers of test cases in CMBB on different terrain types in wet weather.

I have seen Moon's claim that Charles had taken care of this in the past, but it seems that almost all of the empirical tests indicate that whatever fix was made did not completely get rid of the issue.

In my test I used 80 vehicles (40 at each speed half Pz IVE and half Pz VIE) and had the following results:

Summary:

Slow movement 26 incidents of bogging, 7 immobilizations, mean distance before immobilization 265m

Fast movement 18 incidens of bogging, 7 immobilizations, mean distance before immobilization 370m

The details can be found in this thread

[Moon]

Right, well, I still didn't have time to check into this in detail, but I did find a few tidbits from what I think was the last time this topic has been discussed in quite a bit detail. That was back in January 2003. Here's a quote from Charles:

The chance per-check is proportional to speed, so going faster doesn't

help you. In other words, the OVERALL probability of bogging is

proportional to the distance covered, not the speed at which you cross it.

I don't recall any major changes to this in CMAK, so it should still apply as far as I know.

Martin

[Treeburst155]

Here's a quote from Charles:

The chance per-check is proportional to speed, so going faster doesn't

help you. In other words, the OVERALL probability of bogging is

proportional to the distance covered, not the speed at which you cross it.

Let's ponder this statement for a bit. The bog chances per check may go up with speed; but what triggers a check for bogging? Is it time, or distance? I'll bet the check is based on time, and the increased chances per check when moving fast don't completely make up for the increased distance covered between checks.

If checks were based on distance, with chances per check increased for moving fast, we would not see the results we do. The fast movers would be checked more often, and with higher chances of bogging.

Yep, I'm convinced the checks are based on time, and Charles has tried to balance this by increasing the chances per check for fast movers. Maybe an adjustment of the chances per check for fast movers is possible.

Thanks, Moon. I'm always interested in the inner-workings of CM.

Treeburst155 out.

[Moon]

Yep, I'm convinced the checks are based on time, and Charles has tried to balance this by increasing the chances per check for fast movers. Maybe an adjustment of the chances per check for fast movers is possible.

Yes, I think you are right, it's based on time. However, Charles is pretty good at math , so when he says that it's "proportional to the distance coverd", then I would be surprised if the increased chances don't (at least) completely make up for the difference. Of course there can always be a bug. Charles might be a brain in a jar filled with liquid nutrient, but he's still semi-human you know

Martin

[Redwolf]

Originally posted by Moon:

Here's a quote from Charles: </font><blockquote>quote:</font><hr />The chance per-check is proportional to speed, so going faster doesn't

help you. In other words, the OVERALL probability of bogging is

proportional to the distance covered, not the speed at which you cross it.

</font>

[Treeburst155]

Let's not confuse "checks" with "chances" here, Redwolf.

As Charles has used the terms, each CHECK has a certain CHANCE of causing a bog, with a higher chance per check for fast movers. I think we can assume that Charles has indeed made the chances per check higher for fast movers; but, did he calculate this higher chance per check correctly, so that it overcomes the greater distance travelled by fast movers between checks? I think he might have made a little math error here, or there is a little bug unrelated to the math that happens.

You may have a point with the accelleration factor; but I don't think it's that complicated. My testing was done at a steady speed. There was no accelleration involved other than Turn 1.

Treeburst155 out.

[Redwolf]

Well, if we continue speculating some more.

I think we can assume that the CM1 engine works in "phases", that means there is no continuous checking of possible events going on and for the bogging there is no precomputation of when it will bog during the next minute. Instead there are checkpoints in time and a chance is applied at each checkpoint. For simplicity lets say there is one per second although it is probably different and possibly not the same for different kinds of events (LOS checks are much more computationally expensive than -say- bogging checks and will probably have as long phases as possible).

Anyway, lets say the phase tick for bog check is one a second.

So Charles does the bog check at phase tick. He looks at the kind of ground the vehicle is in (open ground etc.), the condition of the ground (wet, mud etc.), the vehicle ground pressure and possibly at the crew quality (unlikely, if at all I guess this influences the unbog chance).

So he figures: hm, that's not fair, in fast move you can cover more ground between phase ticks, I need to calculate that out, and -that's what the quote implies- he wants to have it equal for all kinds of moves so that the chance is equal by distance, not time.

But where does he gets the speed? Just because the vehicle is going with the "fast" move command it can still be anywhere between zero and the max speed of the vehicle.

He probably doesn't want to spend a major engineering effort on this and a rough estimate will probably do, because it is unlikely that some forum idiots come along and dissect this mechanism in detail to figure out how to get 7.5 meter average un-bogged movement out of their tanks.

So, there are two choices for Charles (remember this is my speculation):

1) he can get the speed by looking at the distance actually traveled during the last phase tick.

2) he can just assume the "normal" speed of that kind of vehicle in that kind of ground with that kind of ground condition. That would mean during acceleration you would get a higher big chance per meter.

Solution 1) is obviously more elegant but it would depend whether that information about the last phase tick stays around. But I doubt it does, keeping crap like this would cost a lot of memory. I would guess that at the end of a phase tick the engine doesn't have any idea where these digital dudes were hanging out at the beginning.

Solution 2) would be appropriate if you didn't have the data floating around anymore. And I think it would be realistic. Going one mad rush through a piece of mud obviously has a lower chance of bogging down than doing constant acceleration and deceleration.

For the game results that would mean that if Charles chose 1) then you would get the same meters out of your vehicles no matter what you do. If he chose 2) you would get much fewer meters if you were constantly switching from fast to move (or halt in between).

Unfortunately it is hard to test because you cannot use group move to plot such a path. I wonder whether my boss would mind if I abuse an intern or two for a while...

[Treeburst155]

Redwolf says:

"He probably doesn't want to spend a major engineering effort on this and a rough estimate will probably do, because it is unlikely that some forum idiots come along and dissect this mechanism in detail to figure out how to get 7.5 meter average un-bogged movement out of their tanks."

LOL! Charles is probably amazed that anyone would even bother to analyze bogging to this degree. I just can't help myself. Anything that involves luck, and luck alone, compels me to analyze my chances. It pays off too; but not enough to justify the large amount of time I spend on CM luck factors.

Treeburst155 out.

[junk2drive]

real bog

[tar]

Yeah, but the first 39 tanks made it through OK.