Hi Paul,
I built two Pygmy Osprey HPs, so I hope these thoughts apply to the Tern construction, too.
By "overhang," do you mean the lip which will help secure your sprayskirt; or the overlapping ends of the coaming pieces, where they meet at the center joint of the deck?
If you mean the lip overhang, I'd say just double-check the instructions and your measurements and leave it as it. That overhang is important in securing the sprayskirt down snug. And don't worry about the edges of the plywood being sharp. They've not been a problem for me. If you want, you could probably sand the edges very lightly to smooth them out. Installed as instructed, they're very, very strong despite the overhang.
If you mean the overlap where the coaming pieces meet, I believe the instructions show you how to cut these so that they match perfectly with each other and with the deck on which they sit.
Hope that helps. I'm assuming the Tern and HP coamings are similar. Then again, my coaming was constructed of two halves -- and I noticed your note says they're one solid piece.
Good luck. The Tern's on my to-do-someday list. Great boat.
Grambo

: I'm close to finishing the construction of a Pygmy Arctic Tern. The coaming
: seems to both have a quite large overhang and be quite sharp (it's made
: from a single 3/16" (?) piece of plywood). What have other people
: done with this?

: Should I just leave it as is? Trim it back and round it off? Other?

: ---Paul