The hull "shrinks" (top gets narrower) when the forms are removed for a period of time.  However, you don't want the hull to be in the shrunken (narrower) form for the boat shape to be correct, so when you do the final attachment of hull and deck you need to un-shrink (widen) the hull again. CLC cuts the forms so they will make the correct final shape. 

Wires might be OK, but I have made 2 stitch and glue boats and you really need to get in there and pry the hull out while pushing the deck together to get everything to line up, and then attach it with your preferred method.  I have found that clear packing tape works really well and is faster than wiring for the deck to hull connection process.  It really helps to have at least 2 people and several sticks (to push hull apart) and a putty knife (to stick in crack and pry in appropriate direction).  This process is described in several other posts if you want details. 

Good luck - it takes persistence to get them together, but it's worth it in the end. 

Thanks Kathy for your comment. I had read in one posting that packing tape didn't hold, that is, was not sticky enough to keep the hull expanded - but perhaps that is just one case, or pernaps his hull expansion was worse than yours (which may be my case0

My current thought is not to remove the foms that are reachable from the cockpit and hatch openings, but to fillet and apply tape between them, and then remove the forms. After removal, the small area where they were could be epoxied. The worse expansion seems to be in the center of the boat where these forms are. The 4.5 form (one at front of cockpit) would have to be cut down so 3.5 could be reached for removal, but that would not affect its holding the hull apart. Do you see any problem with this scneme?

I now think your scheme of packing tape would work near the bow and stern where the expansion is not as severe (in my case). 

When I attached the deck to the hull,  I used hot glue (same heavy duty strength I used for the deck forms) to glue a small scrap of cedar to the underside of the deck every 6-8 inches or so along the length and roughly 3/16" from the edge of the deck.  This allowed me to basically "insert" the deck into the hull and those little scraps held the hull to its shape.  Some packing tape  was used to hold everything in place while I syringed some thickened epoxy along the deck-hull joint between the little scraps.  Once this epoxy set, I removed the cedar scraps and cleaned up any left over hot glue with a chisel.  The regular epoxy fillet and fibreglass tape followed.

That is a very interesting, and from my reading the forum, unique idea. Did you place the little stips along the entire length? If so, how were you able to use a syringe all the way up to the bow?

I placed the scraps from the stern to about a foot from the bow...as far as I felt I could reach in to remove them.  I found that once the hull was  spread apart this way, the last foot by the bow didn't need any additional help. 

I used the syringe up as far as I could reach and then used a stick to apply a few dabs of epoxy beyond that. 

Thanks again. The more I think about it the more I realize what a good idea you had because the 3/16 is the thikness of the plywood hull so the edge of the deck aligned perfectly with the ourside of the hull.

BTW, I like your design of a 3 strip sheer with the dark in the center. looks great!

Dogan - your hot-glued scrap/cleat treatment looks like a good way to go - I anticipate needing to do this because I have a portion of my wood duck that required quite a bit of effort to fit the deck forms (pushing out on the sheer panels).  

Two questions
1 - did you place the scraps/cleats a consistent distance inboard of your deck edge?  and if so,

2- did you plane down the deck edge after stripping (and before removing the deck from the forms) so that you knew your deck edge matched the correct hull shape (with sheer pushed out)?

When fitting the sheer strips, I placed the bead of the bead/cove strip outward.  There is a natural line where the rounded bead ends and the surface of the strip starts. I knew that when I eventually planed the edge of the deck that I would be planing so as to entirely remove that bead from the first strip.  Thus, when I fitted the sheer strip, I lined up that natural line with the outward edge of the sheer panel and so the bead itself overhung the sheer panel.

When I glued my scrap blocks to the underside of the deck, I glued them 3/16 " (4mm) from that natural line on the strip effectively ignoring the bead.  I'm probably making it sound more complicated than it is.