I know absolutely nothing about Braidbar narrowboats but I recently had my boat surveyed for insurance purposes . Whilst discussing with the surveyor the merits of blacking the base plate he commented that he had surveyed a Braidbar boat that had huge pits on the base plate , 5 -6 mm I believe he said ,needless to say that base plate hadn't been blacked . As Alan has mentioned those pits could be have caused by other factors but the surveyor mentioned the boat had cost over £100,000 when new . I forget how old he said the boat was but it was certainly less than 12 years.