On my pond most of the fish flee from the boat when it gets close (within about 10 feet) but farther than that away doesn't seem bother them much. Bullhead don't seem to care how close you get to them. We mostly fish from our boat, half of our pond is almost impossible to get to on foot. We don't use any type of motor though, we paddle our boat around the pond. We catch much more fish from the boat then we do from shore. With the ultra light rigs you can sail even a very light lure or hook set up (1/16oz) quite a long distance so you're not fishing anywhere near the boat anyway.

DIED's pond is about an acre and I can tell you from personal experience that his fish aren't bothered much by his jon boat. Once again though no motor is used.

JHAP
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"My mind is a raging torrent, flooded with rivulets of thought cascading into a waterfall of creative alternatives."
...Hedley Lamarr (that's Hedley not Hedy)