One year we had a bird strike in the afternoon, and that night it rained softly we ended up with water in the bunk, if the ladder was not there I would not have been able to repair the center marker light that the bird cracked on top could not see it from bellow in the dark, I used tape to secure and water proof the light until replaced, many times I have gone topside to check on the seams and clean the roof and access the cargo container or adjust the satellite dish, those ladders are useful.
navegator