Off the top of my head...
If the sub is snagged they will take cutting gear.
If it is on the surface 20 miles away they narrow their search.
So far what you've said:
Mariners wouldn't know morse code!
You (not the rescuers) KNOW that the banging is them.
You don't believe knowing that the sub is tangled, powered, on the surface or not... none of that is important.
Are you Simon Jordan?
Who will take cutting gear? there are very few platforms that can operate at those depths, let alone have cutting gear capability that are readily available where needed now. If time were more plentiful, then a more capable rescue platform could maybe get there and all bases for rescue could be catered for.
If it were on the surface, it will have been spotted.
They are not mariners and would unlikely know morse code. The pilot may have some knowledge, but under the circumstances, his priority will be simply to make a noise by repeat tapping at timely intervals.
No, I don't know that the noises are from the sub, but if noises are being heard, what do you think it could be causing them considering the remoteness of the area and depth of water?
As above, with the timeframes involved, knowing whether it is tangled or has no power is sadly irrelevant.
I'm not Simon Jordan, just someone with experience in subs and escape training if stranded on the bottom
We're clearly not going to agree on this, so will leave it there and simply pray they are rescued alive