A line cutting the body plan diagonally from the frames to the middle line in the loft lay-out and usually a mean normal to a group of frames of similar curvature, representing a plane introduced for line fairing purposes.
Umgca osika iplani yesiqu ngokuxwesileyo ukusuka kwiifreyimu ukuya kumgca osembindini kwindawo ephantsi kophahla.