Are Dc's Pressure And Contact Detonation Based?

The questions of whether the game does, or will have code eventually to remember leftover DC charges, may be relevant to the situation concerning minefields... will those stay on forever after being placed by a player if the player logs out (multiplayer).

If multiplayer code can remember minefields, would the situation ever happen that an unexploded DC may stick to the deck of a sub and later be seen when surfaced? This amount of realism is probably to much to ask when all things concerning total game resources are considered... but if some resources could be available would this be desired?