I have been trying to think how to explain it on here. You have to think of it this way. If you built the entire boat to plans, then chopped off the top of the wheelhouse at the top of the gunwall......then built a second wheelhouse and slid it down inside the first one and put the roof on. Everything is tied together through the helm in front, and the bulkhead in the rear. The sides then bolt through and become one with the bottom sides when extended upward.
I compensated for the additional weigh of the inner wheelhouse by building it of 1X2 framing covered with 1/4" plywood for the walls and roof. Everything is solid as a rock with no "wiggly-giggly" at all. I hope that all makes sense.