Hello everyone ,I am sure this question haas been asked many times but .I am /have taken of my rotten inner and outer sills on my Discovery 1 , I have bought new panels from Y.R.M ,and have removed the rotten areas back to where there is a spot welded joint running full length of floor ,approx 270mm from outer edge .I bolted these new panels/inner and outer sill (outer ssill compised of the sill shape and metal of 270 mm depth ) in position prior to welding ,although I cannot weld I was to have a go .My idea was to stitch weld, on showing my handy work to a friend he says that you can no longer stitch weldbut I will have to remove all and thoroughly clean of all paint so that the work can be seam welded as per M.O.T regs .Could not I spot weld the area that was spot welded and also the sill seams .Also what is `plug welding `,thank you Coachman .