QUOTE(dragon1w4e5 @ Mon 27 Oct 2008 0923)

All BMPs have trim vain.
BMP-2
BMP-3
Rather a frontal wave breaker. Most of western designs (M113, M114, M2 Bradley even Sherman-DD had one) has all around Trim vain that prevents water to go over hull level. see:
http://images.google.fi/imgres?imgurl=http...iFI284%26sa%3DNQUOTE(dragon1w4e5 @ Mon 27 Oct 2008 0923)

BMP-1A1. Greek BMP-1A1 crews during river crossing operation, always have their hatches open as you can see.
Sorry man but you just can make those kind of accusations if you haven't done it by your self! Please read at least one properly done book before you come to tell these theories of yours...Because majority that you show to as is total BS!
According to Russian manula and FDF orders: You should never ever swim with your hull hatches open due the possibility of getting water in from open hatch as you don't have all around trim vain. A mater of fact Russian manual orders all hull hatches to be closed during swimming and those are also ordered to seal with special watertight paste that is supplied as a part of IFV's own gears (I've got no clue about its ingredients but we used to call it "bears sh*t" by its looks) - also rear doors are sealed. You can see why from this picture:
http://tanksinmoscow.com/Kubinka/Foto3/BMP-2_05.jpg BTW 1: you can also see in above picture special swimming periscope (that also belongs to every IFV gears) that is about three times longer than the normal one and is put during swimming in place of drivers middle periscope. And this due the waves going over the hull.
BTW 2: Notice that in photo above the BMP-2 looks like its swimming straight and its hull line way over water line, but that is just what the angle of this pic lies.
In fact normally it is only the left side of BMP-2 that is well over the waterline as all BMP-2's have a bit slanting way of swimming due the extra weight that transmission and engine causes to right side as those are situated bit off the hull centerline.
Most of those BMP-1 photos you posted doesn't show swimming. Couple of those show how it is done going in and out from the water - not actual swimming - and others most probably wading over streams than swimming. The last photo though is interesting (I've seen couple of other similar Russians too), it seems to be
possible to swim with BMP-1 (I haven't seen though any photos of BMP-2 doing that)
while empty (no INF Squad, INF ammo, crew and INF Squad gears, RPG's, AA-missiles or IFV's own ammo inside = about 3,1 tons lighter as the swimming weight that is 13t +-2%) hatches open if there is calm waters.
Russian manual though say that it is not allowed - besides it is just purely stupid to drive any hull hatches open if in combat situation no mater are you in water or in land because you can't the traverse turret electrically.
Still this is seems to become just some kind of CV bashing event...while there still is no real comments on the issue.The issue was originally in
post 19 usability of swimming in heavy forces IFV...