[Capnblu]

Ok, so here is my GUESS. I think that your cutlass bearing housing, is leaking around it's perimeter, where it exits the hull. If it were mine, and after reviewing the other suggestions, and ideas, and it still seemed plausible, I would haul the boat, pull the shaft (into the boat), make an airtight plug and insert it into the stuffing box inside. I would get some butyl tape, and tape an area off completely surrounding the cutlass bearing area 2-3' cover with poly so you have an airtight bag, and insert a vacuum source. check and halt any air leaks. Now look for water being pulled OUT of the hull. My 2 cents thinks its going to be leaking on the outer perimeter of the cutlass bearing. For a good vacuum source, go to your local refrigerator repairman, and ask him for a refrigerator compressor. These will draw a nice vacuum to about -25psi. Do not think you can use your own, by cutting it out of your old fridge, Let a professional empty and dispose of the refrigerant. Good luck.

 

[Capnblu]

Sorry, but I do not think you will be able to be 100% sure where or how your leak is located before you actually haul it. Some others ideas of patching for the season, may work, just remember, or consider the removing of any patch that may interfere later. Is it possible that this area froze last winter? If so I would expect to encounter some de-lamination when you get into it. Good luck.