all valid points, but lets assume that a number of enemy sailors bailed overboard from their sinking cargo ship. and the ship quickly sank beneath the waves.
there you are at periscope depth, surrounded by 30 or so drifting sailors all floating by above you.
there is no ship to "hide under" now, only floating men. In real life, as long as those men were floating above you or even floating within a reasonable distance of your sub... no DD in his right mind would plow through them and launch a DC attack on you - because now that he did that every merchant marine adrift in the area is now dead.
i was thinking about a mod for SH3 - the GWX boys have placed dolphins and the like around at random points. you cant shoot them (i tried

) so would there be a way to add the little gunners from the ships that you can see flying overboard as objects just floating in the water? even if they only floated there for 20 or 30 minutes before just dissapearing? you cant shoot them - you cant pick them up - they would just be there for eye candy only.
whenever a man is floating in the water and a depth charge attack is launched nearby, it basically causes his internal organs to explode, depending on the proximity of the attack... the further away from the survivers the attack is the less pronounced the effects of a DC attack becomes, at best, the floater will feel as though he has just gone 10 rounds with mike tyson and this is a distant depth charge attack - a close depth charge attack would result in the survivers being killed instantly therfore if you were hiding under a group of survivors the destroyers couldnt launch an attack until A - you went further away from the floaters or B- all of the floaters were rescued.