A ladder is useful short-term, but carrying paint buckets, tools and other heavy things up and down a boat 25 times a day using a ladder is an invitation to disaster; all you need is one slip to ruin everything. So I decided to make some stairs put of treated lumber, which could also serve as a tool storage shed and outdoor kitchen space. I was able to knock it out in a day. It isn't perfect but it is safer than a ladder. I overbuilt it of course...the fellas at my previous yard told me later folks were fighting over the stairs I had built but had to abandon there when I moved the boat. Most prebuilt boatyard stairs, if not already being used, are pretty rusty and dangerous themselves, or they aren't the right size & fit. For bigger boats it is sometimes worth renting commercial scaffolding, which can be built as high as two or three storys.
For my particular project I just want to make sure there was about 2-foot gap separating the stairs from the boat to allow me room to freely work on the hull on that side. I built the top platform as kinda a Frank Lloyd Wright-ish cantilevered bit that provided cover for my outdoor boatyard kitchen located behind the stairs and also served as a ramp to step over the gap between the stairs and the boat safely. Other design features were solid, secure handrails and good lighting in the form of a solar-charged yard light. All this may seem like overkill but staging a project site is actually important, for efficiency as well as safety.