hi Ghost, thanks for your note - had to look up a few words
So, today I learned that there is a structure called Breakwater ... it was just a name I made up
and I've learned that oblique means an angle not 90 percent (did know the word in its font use though)

Concerning my Breakwater ... it is at the ocean, but I haven't gotten around to map the harbour/docks/breakwaters yet, still busy with the land structures - I'm planning to make some docks for fishing boats in the river close to the sea as the original harbour, then as the city grew they added a new harbour on the ocean side. When I get that far, feel free to correct me in my attempts to map those elements