how to get a job Shipkeeping

[ssamericanracer]

I have found a few articles about shipkeeping, describing the duties of the job and such, and while it may not be non-stop fun, I'm still wondering how one could get started and hired on as such. Are people with licences preferred? Are these jobs just listed in the classifieds in the local area, or does one contact the shipping company? I am assuming shipkeepers are employees of the shipowners and no the port authorities. Any info will be helpful. Also, do ships on long-term lay up (?.S. John Sherwin, etc.) tend to have keepers?