Interesting article, @nexrules! You've taught me a few things, and you have included some really great pictures.
To answer your question, aren't those things that hold, raise and lower the lifeboats on a ship also called derricks?
I've upvoted and resteemed this article as one of my daily post promotions for the @mitneb Curation Trail Project. It will be featured in the @mitneb Curation Trail Project Daily Report for 15 JAN 2018.
Cheers!
Way to go @mitneb, yes they are although they usually go by the name crane most of the time. A Derrick is an assembly for lifting heavy equipment from one place to another. You're correct. Cheers