What causes this - is it bad?
 

i've been looking at some boats for sale and some have the paint on the lower unit near the prop chipped away. is this a common condition?

http://home.comcast.net/~erich.baumg...utdrive(2).png

Your pic didn't work.

Judging off what you said, IMO a little chipping of paint over a few years isn't abnormal. If there is alot of chipping, it could mean that it got real hot. Also IMO if you are looking at boats for sale and they don't spend the $5 on a can a paint, look over the boat good.

I would much rather look at chips when shopping than wonder just what is hidden behind the krylon detail job.......

TTT - fixed pic

That picture is to large it will not fit on my screen can you make it smaller for me? :D

Make sure you have the correct zincs on the drives. You use different ones for salt or fresh. Maybe you have the wrong ones?

i didn't even think about it being corrosion. excuse my ignorance, but is that what it is? i've always had outboards so i've never had to worry about it. like i said, i'm looking at buying this boat, so should this make me think twice about it?

here's another pic:

http://home.comcast.net/~erich.baumg.../outdrives.png

kind of looks like electrolysis

Thats normal,,they all look like that after a while.

Check the zink annodes behind the props if they're still there...

It looks like it's been left at a hot dock.

Stray electric currents from shorepower, whether on that boat or another one close, can cause electrolysis. It looks like electrolysis.