: 1. Is there a putty or something that can be used hide the wire tie holes on
: my hull panels.

I put 3M blue masking tape on the outside of the hull over the holes and the seam when I epoxied and glass taped the insde of the seam. The holes just filled with epoxy. They don't show too much and its fun seeing the light shine through them from the inside. The tape also prevents drips and runs from bleeding through and discoloring the hull before taping the outside.

: 2. How far behind the backband should the cockpit opening be.

The real question is where should the paddler be located in the boat and then position the cockpit to the paddler. I found the CG to be 12" in front of my back in my Yare. If you are building to plans or a kit the cockpit should be located correctly. I velcroed the carved foam seat to the hull and used adjustable straps for the backband. I can make CG adjustments by moving the seat.

: 3. Has anyone used 2" minicell for bulkheads. The 3" seems really
: thick and heavy. I was thinking about slicing alittle off for other parts
: of the boat.

I used 1/8 inch plywood bulk heads. They really helped to shape the radiused deck.

: 4. The hull panels are slightly unfair running along the chines of my boat.
: Also the panel joins at the bow and stern mismatch by about an eighth of
: an inch. Like a dummy I glued it all together already.....

Not to worry. Round off the outside corners slightly, by sanding, to remove any offsets before taping the outside of the seams. The deck runs wild past the shear clamps and is trimmed to mach the sides. When you plane the shear clamps for the deck radius, eliminate any vertical offsets at the bow or stearn.

: Is this not uncommon. Will the boat paddle in circles or something.

I added a little trim "tab" at the stearn of my Yare to trim out a slight turn by sanding one side and adding a few layers of glass and epoxy to the other side of the keel at the stearn. Yares don't turn when you lean; its all with the paddle so the trim helped.