Just about any S&G design, including my own, is going to require temporary station forms, as many as five, to help hold the designed shape of the hull until a layer of glass is applied to help hold it in place.

Also, even well cut out panels need some work to be faired out well. Here is a paragraph from my instructions regarding the stitching process:

"Now comes the most critical part of plywood kayak construction. It is extremely important to sight down the chines, and especially the keel, to make sure that the lines are fair or straight. These lines can be checked most accurately with the hull upside down. Look for hollows, bulges and hooks, especially in the keel. Now is the best time for any adjustments to correct the lines. If the lines are not fair or straight, first check to see that the panel edges are even against each other. If necessary, loosen some wires, push and pull the panels until the edeges are even, and then retighten the wires. Along the keel you may need to tighten the stitches in the area of bulges and loosen the stitches in the area of hallows. Small wedges of wood in the seam help to remove larger hallows. It is OK to have small gaps between the panels to avoid hallows. Any gaps can be well reinforced later with fiberglass. Also, make sure that the kayak is not twisted. With the hull right side up, sight along the vertical lines on the stations and the bow and stern stems to make sure they line up. If necessary, twist the hull to get them straight."

http://www.rollordrown.com/kayak/pb175.html