Sitting down while at the Helm is a boon, especially on long watches.
I followed the curve of the bridge deck/traveler for the design. I rested it both on the aft deck area right next to the pulpit supports and on the cockpit sides. Originally, I notched the seat so it fit between the pulpit supports and they held it in place. But my wife is short and needs to be closer to the wheel, so we moved the seat forward and secure it with a webbed strap that goes around the post and snaps to the seat side, keeping it from moving forward. (If I remade it at this point, I would not bother with the notches at all.)
I took three pieces of teak; cut the curve across the top, screwed them together with bracing in between, and then screwed "slats" in place across the top. A Marine Surplus had teak steps from Wellcraft manufacturing that worked well for decorative slats. The slats are 16" long and the seat is 34" wide. We have a 4" vinyl covered cushion on top for padding. Because the back stay "cuts through" the area, you must sit on either side of the stay. I didn't want the more sharply curved seat since I sit on the low side when tacking in order to see the sail. For more comfort, we added two 2" nylon straps laced between the two pulpit posts to support two seat-back cushions that double as cockpit seats forward when we're not underway. These two have a strap that fastens them to each other so they don't move out of position.
Cliff and Bezy McKay on Ceilidh (Kaylee) Hull 261