if you want to do a chesapeake with a flush hatch and no obvious stuff on the deck, you basically convert it to the same system as a shearwater (to get the flush element) and then repeat the same operation you described above to replace the toggles.

in terms of material, you then need a spacer and shelf piece below the hole you cut for the hatches.   the chesapeake kit comes with a seperate piece of wood for the hatch which can serve as material for the 'shelf' peice (assuming you use the same shape hatch per the plans).  with respect to the spacer piece, some 3 mm okoume is all you need and it can probably be done with 4 mm scraps that get created from the deck if you don't mind glueing a couple pieces of wood together. 

if you want to make it easy, however, i would just order the kit with the flush kit option.  see the following link: https://www.clcboats.com/modules/catalog/product.php?category_qn=boat-gear&subcat_qn=kayak-gear-accessories&code=kayak-flush-hatch-kit

CLC also sells a an invisible hold down kit  https://www.clcboats.com/shop/products/boat-gear/kayak-gear-accessories/bungie-hatch-hold-down.html which makes it easy.  of course you can configure your own...its just time.

to the extent you want to do something really interesting, you can also do an invisible hold down with rare earth magnets.  a little google search on the topic and stuff will come up.   but in my view, that starts to get a little too complicated for me.

hope that helps

h

   Thank you so much.  And, "Duh..." now how did I miss seeing that the flush hatch kits were for sale?  Were they there 8 months ago?  I'd already seen the invisible hold down kit when I was building the Shearwater, but decided to make the hold downs on my own.  Maybe a case of not seeing what you're not looking for, and since the Shearwater hatch was already flush I wasn't looking?

I like challenges.  It is no fun having problems solved so quickly, so I'll have to think of something else to fret about now - like maybe actually getting the kayak kit on order.  Thanks again.

   OK, I'm now about ready to put the deck on the Chesapeake, and not so long after to do the flush hatches, with kit in hand.  I'm thinking about not following directions - imagine that. 

Anyone with thoughts on this idea? Like the Shearwater, I intend to use the deck cutout (matching grain) for the hatch lid.  But unlike the Shearwater (no curvature, cut out the hatches prior to any glass/epoxy coating) why not completely finish glassing the Chesapeake deck first, before cutting out the hatch?  Before final coat on the glass I'd make the cutout.  With the epoxy on the inside and glass on the outside, I'm guessing that there will be little to no springback of the hatch lid back to flat, and whatever there is can probably be taken back to the correct curvature with the strongbacks that glue under the hatch just as easily as putting the bend in raw, uncoated plywood (because the curve will have already be in the "memory" of the glassed hatch).  Anyone with experience in this?  Stop me before I sin.

The only technical tip I've thought of myself will be to score the sabre saw cut line with a knife or dremel prior to sawing.  It might not be necessary, but might help prevent any tendecy for the saw teeth to lift the edge of the glass away from the wood.  And yes, relatively fine teeth, sharp blade will be in the saw.

Dear Bubblehead,

I have not built a Chesapeake, but have bent a bit of plywood. The glass will help resist, but not stop the spring back. I would recommend epoxying a couple of shaped pieces of wood to the backside of the hatch that will definately keep the plywood in the correct camber. can even be plywood at right angle to the hatch with generous fillets.

Joel

Bubblehead, 

i admire you for thinking it through....and i agree with you....while you are trying to create a certain effect, your order of construction often changes depending on circumstances.  so i am in total agreement that you should complete the deck of the chesapeake including attaching it to the hull prior to cutting the hatch and doing the under deck work.

the key difference, that you picked up, is the deck does not assume anything close to its final shape until it is attached to the hull.   this is very different than the shearwater construction where the deck is 'pre-tortured' into its curved shape with a temporary bulkhead.

i also agree with Joel, that you will experience some spring-back and you will probably need some structure (shaped pieces) to hold it in position.  that said, you can wait and see what happens.....and decide then what you want to do.  

on the teeth pulling up the glass...my experience is that i would not worry about that with a fine tooth sabre saw.  personally, i usually just use a japanese pull saw and have had less 'accidents' when i do it by hand and simply mentally commit that it is going to take a bit longer.

anyway, good catch on thinking about the order of construction.  i think it would have been a mess otherwise.

h

  "..... my experience is that i would not worry about that with a fine tooth sabre saw.  personally, i usually just use a japanese pull saw ....."      I agree.  It takes longer to screw it up with the hand tool vs power tool and you can adjust.

Your concern with spring back is correct.  I still don't have a good seal on my rear hatch. I made a second built up hatch and was a little slow getting the backing on and the hatch flattened out.   The flush hatches will be better but more work of course.

   Update:  The hatches turned out fine. There is just one 1/8 inch wide gap aroung the hatch perimeter, and the wood grain matches, so the whole hatch is pretty invisible from a few feet away.

I used the fine toothed sabre saw for the cut (started with a dremel blade for the initial punch-through blade slot).  I used wide blue tape just to give me something nice on which to draw the hatch outline and limit saw base scratching, but no indication of any desire for glass to lift away from wood, tape or not.  There was some spring-back to the hatch lid shape, maybe 50% of the curvature.  This was easily pulled back in to shape with clamps when I added the under-hatch lid strongbacks.  I added a third (middle) plywood stongback even to the smaller hatch.  This allowed me to cut the "hooks" for the bungee cords right into the ends of the center strongbacks. I used a custom sort of design for the hatch rim reenforcement/hatch lip support rim glued under the deck.  

All that is left to do is the varnishing and rigging and sticking on the foam gasket tape. I intend to put one loop of webbing (just like the deck cargo bungee loops) onto the top of the hatch lid (screwing into the strongback) to serve as the lid-lift device, even though something smaller and even less noticeable might suffice.  Bungees will serve as the hatch lid hold-downs; I epoxied a small wood block with holes near the port and stbd chines on the hull interior under the hatch openings as a place to attach the bungee loops to the boat.   I intend to stick the gasket tape to the the deck, not the hatch lid. That might help with overall water-tightness of seal just a bit.