I just returned from an enjoyable 8 day kayak trip in the Canadian wilds (see the trip report on the Trip Board if you are interested) so I can now say with authority that you do not need to cut finger grooves in your deck if you use the knob style hatch closure system, shown on the Eric Schade's Shearwater Boats site. My version of Eric's system passed the litmus test with flying colors.

I put a compression spring between the bottom of the hatch and the hatch closure bar. When I loosen the knob that closes the hatch, the spring pushes the closure bar and hatch apart and the hatch lifts away from the deck. No finger grooves needed. Give the laziest man a job and he'll find the easiest way to do it. I'll post pics of my hatches if I've not made myself clear and anybody is interested.

Now if you'll excuse me I have 12 days of catching up to do on my Kayak BBS

Ken