OH MY GOD.
Michael, I do believe you've cracked it.

Eveleen left Aye for Belfast on 6th May, and a direct route would take her straight past Corsewall point (the area the uboat.net has listed as the area Sandhurst was sunk on the same day).
Looking at the map reference points in question, I can't believe how close Eveleen is supposed to come to a point where UB72 is already known to have an acredited kill that very day.
Her path is as straight as an arrow over the kill zone.

As you say, depending on the times of ships leaving port and being sunk, it would be almost conclusive Eveleen was sunk by this particular boat.

I think the circumstantial evedence alone makes UB72 an extreamly likely candidate for the two sinkings.

And as you've mentioned that weather would not be thought of as a factor in the sinking (and ships don't disapear outside the Bermuda Triangle) I believe this is the most likely answer.

Will contine to try to find out more about the exact times, but thank you very much for putting me onto such a positive lead.

Neil