This poor photo shows the true keel, which is very thin. The covering board has cleats on the bottom of it to ensure that the true keel is kept straight during construction. When I took this picture I suddenly thought I had used the wrong timbers for the first two stringers, but I haven't, so that is a bit of effort saved.
The slots in the frames for the stringers have to be filed slightly at an angle towards the end to accommodate the sloping stringers in straight cut slots. The first stringers are marked and tied at the ends to ensure that the hull is symmetrical, which looks OK here. The tricky part will be to cut them to length and chamfer them to fit either side of the stem. The designer says the simplest way is to sand them with a power file or sanding block until they fit. I will try my Bosch multi tool to see how that works