The next stage being to mask off from the waterline down to the mid-point of the submarine. Doing a bit of research on this subject, one shipyard would paint down to the mid-point, while another shipyard would only paint to the waterline, leaving the red antifouling visible just below the waterline.
A light dusting of black, from a rattle can, went on first, followed by green, misted on along the waterline edge and in downward passes, in a random fashion. With the masking removed, the effect looked a little 'fish' like at first. Also, the model had suffered some damage from the removal of the masking tape. Once this was made good, and following a couple of hours to set off, I assaulted the paintwork with a medium Scotchbrite pad, red I believe, and an old shirt. Light downward strokes in the direction of any water run off or general wear and tear. This helps to blend in the green misting and helps to show off the shape of the sub.
The last shots showing the model with the corrected paint damage and the blended effect of the green to good effect.