Bogging happens when a vehicle has become mired in soft ground to such an extent that it cannot move. The vehicle is said to be bogged. Bogged vehicles risk immobilization.
A bogged vehicle cannot move. It displays a “Bogged” text on its unit panel. Its move commands remain intact, and it will continue performing them as soon as it becomes un-bogged. Bogged units attempt to un-bog themselves automatically, which will usually succeed after a minute or two. However, there is a significant chance for each bogging event to turn into immobilization. This chance seems to vary with the terrain: it has been observed as roughly 1 in 10 in mud, but perhaps as high as 75% at road edges.
As of CMBN 1.01, immobilizations from bogging seems to happen at a high rate. However, no exact details of the bogging system and subsequent immobilization are known. Here is what can be gleaned from the manual:
- all vehicles are rated for offroad performance. In CMBO, all vehicle types had a ground pressure statistic. Therefore it is likely that all CM games have ground pressure for each type of vehicle.
- Fast moves have a somewhat higher chance to bog.
- Bogging is likelier in some terrain types than others -- mud is probably worst, roads best.
- Ground conditions affect bogging. Ground conditions can change during the course of a battle; e.g. during a downpour, ground conditions may change from Wet to Muddy.
- When a vehicle drives over an obstacle (low wall, fence, etc.) there greatly increased risk of immobilization and bogging.
There is testing work going on at the forums to try to figure out if bogging is buggy or not, and to try to get some general sense of how it works. (See this thread, in particular this post by Lt. Bull.) Here is what is known from this testing work, so far:
- ShermanM4A1 (mids) with regular crews traveling Fast over GRASSXT terrain in a straight line, with "dry" ground conditions, will suffer on average 1 bogging every 150 km (150000 m).
- The same setup as above, except using MUD, results in 1 bogging per 350 m. That is a rate of roughly 428 times the rate on grass!
- The mud test showed that 1 in 10 bogging incidents resulted in immobilization. This number is consistent with the grassXT test, where there was insufficient testing to get enough immobilizations to be confident of a rate.
In another thread, the result suspected by many players was confirmed: bogging (and subsequent immobilization) is much likelier when tanks are partly on a road and partly off. Thus, when drive on roads you should be very careful to keep your tanks fully on the road.