I was about to prime the mezzanine deck and just in time remembered the overhead lifting track that runs around the sweep deck, and then back to detailing the superstructure my rule of thumb is, if it's glued to a flat surface like doors, vents. various pipework etc. I do it before painting, if it stands up from a deck, guns, winches etc. I do it after painting with the exception of bollards and fair leads, ho and the foc'sle water brake, ok it's a very loose rule of thumb, and she now has her pennant numbers.