no doubt they are moving at something like 20knots? you probably havn't much time once they sail pass thats it! my advice is get as close to your target as you can running at 2 knots (as long as your in front of them). then let loose your fish on the BB.
I came across a huge taskforce in my last patrol sailing with a convoy, 2 nelsons, 2 carriers, the king george and a heavy cruiser all moving with the convoy at 6 knots! There was no escorts. Sunk the light carrier and one of the nelsons.
Good luck
