Jim,

Sounds like how the Mill Creek is constructed.  I like sheer clamps in a boat.  I recommend you put a plastic screw in port hole in the bulkhead.  It allows you to store some items in the water tight compartment while still providing flotation.  I think the most important thing it does is allow air pressure to equalize with the atmospheric pressure.  If your boat is sitting in the sun, the pressure could build up in there enough to damage the boat.

To deal with equalizing pressure, after having a hard time opening a hatch after putting the yak on cool water, I did a "drill-fill-drill" hole near the top of the bulkhead & just under the deck.

I drilled a ~1/4 hole, put tape on the back, filled it with thicked epoxy, let it dry, then drilled a 1/8" or 1/16" in that. If it ever gets in the water (upside down) not much water will flow through it.

Other reasons for a hatch is to provide access during completion work and to have a way to reach in for repairs or modifications in the future, and to have access to let it dry out if needed.

Jim,

I did this on my daughter's Ganymede and it worked out well. You can see photos and narrative at http://twofootartist.com/ganymede-construction-notes/

Left click on the photos to enlarge them to full screen.

-Wes

Our two Shearwaters that are in the hull fillet stage have had the front bulkheads already cut out for the 6 inch screw type hatches so that we do not have to cut the front deck for hatches.  I probably will drill a small hole in each hatch for air pressure release, since the hatch seems to have the perfect spot lined up in the middle of the hatch cover.  

FYI: I have screw type 'deck plates' in the bulk heads of both of my Shearwaters. Looks clean! Not sure I would do it again because when capsized and the boat is 'righted' the water left in the cockpit can[did] seep through the hatches- filling the ends- about impossible to bale out at sea. So, with traditional deck hatches, once the boat is flipped back correctly, water will stop coming through the hatches, not so with a cockpit full of water and bulkhead hatches. Yes, I know they shouldn't leak but they do a little.

Lew

Jim.  Woodsy3b is correct again.  I built the MC13, got in a hurry to get in the water and did not put in the bulkhead hatrches.  Parked it in the sun while I had lunch the boat was on top of the car.  The sealed bow with no way for the pressure to equal itself resulted in blowing up and breaking the seam between Sheer panel and Bilge panel.  Easy fix but lesson learned.  I have built 3 more mc13 they all have hatches.  Either screw in or flush hatches.  Have fun.

Lance

Lew: I'm a little concerned about your incident with capsizing.  Were you using a spray skirt?  Did you seal the hatch perimeter border with marine silicone?  Have you thought about putting some form of sealant or an o-ring under the hatch cover?  A six inch o-ring should be easy to find.

Lew, Beckson deck hatches http://www.beckson.com/screwout.html, the best I've found on the market, do not leak when properly installed. I drilled a 1/32 inch hole in the center of the hatch and never have a problem. SEEYA Jack