The technical argument at issue here is more simply viewed if one compares the water to very "thick" wind, if an uplift from this and some inherrant bouyancy in the vehicle is sufficient to negate the friction of the tryres away you'll go.
Water also is pretty dense stuff, there arent many people who can actually stand in fast moving water above calf height, I didnt believe it till I tried it. I've also seen a diesel landrover with its backend floating up unable to move, doors and load area open etc.
Quite right which is why the vehicle needs to be flooded BEFORE it can float off.
Used to do quite a lot of caving so know what you mean about fast moving water!!!
Just love the 101 - missed a mint one a few years ago - ambulance version - local scappies sold it for £250 - bloke later sold it for £4,000!!!
To preserve you pride and joy have a go with Acrypol - awesome stuff for use on a roof - can even be put on in the wet!!! Just pressure wash/wire brush the underside and slap it all over - really easy and will stick to anything - £40 tin enough for 2 vehicles. I followed that off with waxoyl underbody seal - mates Rangie still looks like new underneath 4 years later.
My poor 110 not looking too good at the moment - mate of mine offered to do a full restoration on it for £400!!! Told him he was nuts but he needed the cash - trouble is I had a perfectly drivable 110 - now I have a kit car!!! The bodyshell is off at the moment and we have been sandblasting the chassis - not a hole anywhere thank God - not bad after 17 years of hard use!!!
If only! 
