Well it looks like Duff stuff to Me.
From the Evidence the piccie shows things are not right.
As said, the Job looks wrong.
A poor "Job" at best.
If the piccie dioes paint a"Thousand Words" a few Thousand Pounds should be changing hands.
The fact that the small holes are not "Concentric" is not the Total issue but as they are not gives leave to think that the whole "Job" was not correct at the time of build.
Taint normall for stuff not to be aligned.
The doubt that springs to mind therefore is the Stern Tube and all that goes with it was not correct either.
I aint no Marine engineer but I have just gone through the Whle Gambit with My boat.
From the piccies, which is all I have to go on.
I would say Yes.
There is a Case.
How tight?
More info, piccies, etc etc are needed.
No, it was the first thing I checked. Water is coming from aft, and dripping from somewhere above the waterline. I suspect some through the hull fitting (bilge pump exit or so).
Just a thought - I had a leak only on starboard tack. It turned out that the bilge pump exit through the hull didn't have a swan neck, so as soon as it was below water, it just flowed in.
I also had the same problem when heeled hard over on starboard tack, and it eventually turned out to be the electric bilge pump backfilling. The skin fitting is above the water line and it took me a lot of investigation to discover the cause
We now have a valve on the outlet which we close before sailing - problem solved