Here you can see the difference between before and after sanding the bog to a fair finish. The idea is to create a flat surface chine to chine. I haven't filled the gaps chine to chine so I wont get a totally flat finish, I will have a slightly concave finish as I feather the bog from the tape edges toward the middles  meaning the centre between each edge will be slightly lower than the tape edges ammounting to fractions of a millimeter difference and imperceptible.