It does look like the chainplate itself is inside the knee in that photo, but it's actually bolted to the outside of the knee. Here's another photo of the same chainplate that I didn't post, because it's slightly blurry, that shows it more clearly:
That being said, they look kind of small to me - and I have heard of A-30 owners having trouble with the forward lower chainplates
, so I will no doubt look into it more before I do any boisterous sailing.
If your chainplates
are stainless steel, and are encapsulated, I'd probably dig in and have a look-see, and possible move them "outside." But then I'm not a fan of stainless (the world should be bronze!), so I tend to be suspicious of it. As I understand it, stainless requires air (or flowing water that contains some oxygen if underwater) to form the protective coating that makes it stainless, so when it's in an oxygen-starved environment, it can develop nasty things like crevice corrosion, and subsequently fail.
I'll probably take the paint off the chainplates
on my boat, at the very least, just to give the stainless a bit of air (perhaps it can get some through the paint, but I'd like to be able to see them anyway).