: In the past I've made foam knee hooks which I've glued under the
: deck/coaming, but would like to try wooden ones on the kayak
: that I'm making for my nephew. I've stripped the deck and the
: cockpit recess, but have not yet done the coaming or even cut
: out the cockpit opening. I am considering just lengthening the
: strips of the recess so that they'd narrow the space at the
: front of the cockpit opening. I'd put on the coaming then run an
: extra layer of strips under the recess and under the coaming so
: that they extend to where the paddler's knees will be.

Another strategy would be to make a 'keyhole' cockpit opening, where the deck forms the knee brace and the coaming rim width varies.
http://www.atlantickayaktours.com/images/retail/Kayaks/NDK/Romany-HV/Knee-Bumps-top.jpg
There are lots of commercial examples of this.
I'm building a boat inspired by commercial designs right now, and the better commercial boats have a pronounced curve on the deck to form the knee 'bump' or recess. It's not easy to duplicate with strip construction - easier to just make the deck a smooth profile and then pad down with foam.
If you can have a 'good look' at a bunch of (good) commercial boats you will get the idea pretty quickly.

: Does anyone have dimensions for a comfortable size and distance
: apart, for where the knees should be? Also, I'd like a shape
: template if anyone has one. I've always just used trial and
: error with the foam ones, trimming until they are comfortable.

If folks of different leg lengths are to use the boat, there has to be some fore-aft flexibility built in. The seat position is pretty well 'locked' (relative to the center of buoyancy) so knees will fall in different positions. So think 'trough' for the thighs.
As for dimensions:
On the NDK Romany, the keyhole-shaped cockpit cutout is (all dimensions approximate) 32.5L x 15W. The 'keyhole' at the forward end extends back about 10.5" before it flares out. The width of the keyhole area is about 8" at the front, 9.5" further back. The outside of the coaming rim is a smooth oval-like shape 35.5 x 18.

Even without the keyhole, it's possible to make a good thigh 'grip' without padding (other than a thin foam for comfort), with the right deck shape. The Mariner kayak decks were built to accommodate the sliding seat and are comfortable (for me) with a seat position that can vary 8-10" fore and aft. It's all in the deck re-curve shape.

Have a look at the NDK Pilgrim for an example of prominent 'knee bumps' - not something easily done with strip construction!

I don't much like the 'sticking out fin' style of thigh 'hooks', though they are popular.