I took a new photo of the starboard stringer today showing how it bends and changes from being edge on at the rear to flat at the front. Since taking the photo I’ve fitted a block between the two stringers shown here. And made a matching stringer for the port side.
This roller is mounted on the cabin roof just behind the transverse beam that is there to prevent water running down the cabin roof and dripping into the cockpit. Using rollers rather than slides should make the roof easier to open/close. I need to do more adjusting though, I realised today that the roof gets wider when it’s hot. When it was cold early ion the morning the hand rails are closer together and bind on the roof but in the afternoon (it was hot today) it moves freely.
Still need to do a little more woodwork on the front edge of the roof frame, then order the aluminium sheet to clad it.