I dunno if it counts as being onboard, but a few years back I visited Muskö(A swedish underground naval base), and I got to see one of our most high-end subs being picked apart for inspection, we're talking EVERY single bit of metal, electronic etc all picked apart inside this huge base inside a mountain, I can't remember what class the sub was, but I did get to walk in the area where it was picked apart, does that count as benig onboard?
