Find out what it is from first . As mentioned bad bellows be it shift or driveshaft can cause more damage like input shaft seal corrosion and resultant leaks and ujoint damage. Bellows can be tough to spot given turning and raising of drive can leak or not leak at various points.
Could very well be from a loose cooling water hose or rubber on exhaust side.
As mentioned if bilge pump or battery dies then you can sink. If a trailered or hoist kept boat maybe if you know where it is leaking and you stay on top of it. If a slip kept boat you are playing with fire.
I broke my grandfathers boat lift years ago because bellows was leaking. Was fishing for an hour, couldn't get on plane. See bilge full of water, run bilge pump don't see water coming in... go on my way, put boat in hoist just high enough to take it out of the water a bit thinking im going to fish after dinner. Never go out, go down to hoist at 10 pm to pull the boat up... two back legs of hoist bend below water line...
The hoist and boat were 25 yrs old at this time, my 17 year old self didn't realize how much water I was taking on, and my grandfather didnt know his bellow were torn until next spring or the year after when the leak got obscene. Thought hoist was rusted below water line but real issue was the boat was full of water.
Im making a short story long, dont F around with it and spend some time assessing the leak before you cut corners and go out in what is essentially a sinking boat.
