Ferry Plumbing?

I was looking for something to blip on the trip home today and spotted this. I have no idea why I find things like this interesting - maybe because I have no idea what they are and what they do - but I like the shapes and details of them.
I had a great time with family on the weekend and am glad to be home. I'm looking forward to catching up with all the blips I've missed in the past few days!