The temp forms are lower than the side panels so that the deck and hull temp forms do not hit each other when you mate the hull and deck together when tack gluing the boat.

I don't know if there is an issue on the Wood Duck 8 but on the 12 you need to make the forms shorter than the plans on the 10' forms and you need to move the 8' deck form so that it doesn't hit the rear bulkhead.  I built a slightly smaller 8.5' form and used that instead of the 8' form so that I could mate the deck and hull without any forms hitting.  

I checked the permenent bulkhead - it's smaller too. so it doesn't mate the deck and there is a gap. :( I wander how all this works on the kit.

I built two Ducklings from plans and didn't have this issue. Have you beveled the panels as indicated in the manual? This will tighten things up about the forms.

Some pictures of your predicament would help.

Good luck,

Patrick

   here is pictures. I just measured the plans. 1/4 inch diff on one measure. So for 2 side pallens it adds up to 1/2. this is a lot.

  I didn't bevel the edges when I test fitted things.Overall the bottom part of the hull is tights, of course, with exception of this 1/2 diff in size :)

Here is bulkhead measured for the bottom-side pannel:

here is corresponding measurment for the pannel:

I wander what do I miss in this? 

Unfortunately the pictures didn't post properly. The bevel will definitely tighten up the fit, and with it your problem may evaporate. It needs to be done anyway, so I'd give it a shot.

Good luck,

Patrick

will do beveling and see if it helps. :)

   I ended up with 1/4" to 1/2" gap above my rear bulkhead.  Filled it with epoxy and wood flour to seal off the rear watertight

Canmore - this is what I observe too.

I beveled all the sides so it did give me some better fit. However I'm still about 1/4 gap between aft bulkhead and deck. I think about trimming some of the wood off the sides. This is going to be interesting.

 I departed from the original design by stripping the deck (as with a hybrid kayak), using the temporary forms as guides. Even so, I also found it was difficult to maintain a tight fit between the deck and permanent bulkhead. The deck curves up rather sharply from the bulkhead. The deck resists the abrupt transition and tends to lift off the bulkhead a bit. When it came time to join the deck and hull I placed bricks on the deck at the bulkhead to press it into place, and I used a piece of fiberglass tape to bond them together permanently.

While my build was unorthodox, I would guess that you’re experiencing something similar. Maybe this would work in your case, or you could just fill the gap as Canmore did.

Good luck,

Patrick

Bricks + beleving + filling gaps with epoxy - this what I end-up doing on this build. On next build I'll make aft bulkhead 1/4 inch "taller" or probably 1/2 inch just to be on the safe side.