[Sailor Steve]

Fitting through tight chokepoints, lots of ships starting or stopping; these can be scripted in, but you will have dozens of ships colliding, burning and sinking.

Also not modelled into the game apparently are the dozens of harbor patrols, both ship and plane, which is why no u-boat ever went near places like Liverpool or Portsmouth - realistically you would be spotted in the shallow water and sunk very quickly. Look at the boats that tried to interdict at Normandy...all sunk.