[desirableroasted]

At 5Kts, an elite escort certaiinly might hear you and investigate. A dull one might pass 1000 m in front and never twitch. You never know.

Remember, your great advantage is that you move in three dimensions, while your opponents cannot. The ability to go deep is your best friend in this game, which it is why it is madness to run the Channel in wartime: you can do it, but if you are caught, you are sailing around in a shallow bathtub.