I think my Ches 16 has the keel about 1 1/2" lower than the chine, right in the middle. Unfortunately the boat is at home and I am at work so I cant check it-but it definitely isn't flat.
I am building a second Ches 16, with all the offsets done at 12 3/4" (so the bottom panels just fit onto a scarfed 16" plank, for an overall length of about 17 feet), and will be reducing the beam about 1/2 inch.
I think the 16 picks up volume in the bow just a bit too fast, which means that in a two foot chop, the bow is always lifting right out of the water as far back as the front hatch, then crashing back down again with a big splash. These conditions are common where I paddle, and the continual splash...... splash...... splash really gets on my wick after a while. Anyway, I am hoping the small hull shape tweaks will help reduce that issue.
I am also reducing the height of the sheer about 3/4" (at 5'9, those sides are really slightly too high for me), flattening the rear deck to make rolling easier, moving the front bulkhead back about a foot to reduce cockpit volume (I STRONGLY suggest you do this), adding a second deckbeam under the foredeck to make up for the fact that the bulkhead has moved back, making the cockpit combing a bit smaller than the plans (if you are small enough to be paddling a 16, you probably don't need that jumbo deluxe size hole).
Dont get me wrong, I think the 16 is a great boat and I really enjoy paddling it-and when the waves get up to three feet it starts to surf really well.
But dont be afraid to tweak those plans-the world won't stop turning and you won't sink!
If Lee G reads this, I guess I'm in trouble, what with stretching his baby every which way.

Pete