MC: Tanks using Snorkels

[Volcano Man]

Here is something I just found... it is from Wikipedia of all things which we know is not always accurate but this sums it up nicely:

For most tanks, water operations are limited to fording. The fording depth is usually limited to the height of the air intake of the engine, and to a lesser extent the driver's position. The typical fording depth for MBTs is 90-120 cm. (3-4 ft).

However, with preparation some tanks are able to ford considerably deeper waters...

This type of fording requires careful preparation of the tank and the ingress and egress sites on the banks of the water obstacle. Tank crews usually have a negative reaction towards deep fording. This has influenced tactics in those countries where the psychological health of the crews or their capacity for rebellion is taken into account...

This sums it up nicely, it is just something that would not be done and if it were it would be one of those risky ops that might happen once and at great loss. With that in mind, it does not make this justification to give soviet tanks an amphibious flag because it would not be realistically considered the norm. I know I have never been on a tank that could keep rain water out of the hatches, much less be considered air tight enough to submerge under water. I am sure anyone else who has ever been on a tracked vehicle would say the same thing.