Using both this and Cargo Ships with the natural continents preset, water based oil patches spawned by the Cargo Ships mod are never generated.

Have tried turning off replace vanilla water setting but issue persists. Disabling mod causes oil to generate on water again.

Thanks for letting me know. I believe this requires changes to the Cargo Ships mod to resolve.

I looked at the Cargo Ships code and found two possible issues:

(1) If on_chunk_generated is called on that mod before this mod, then oil patches will be placed before this mod has had a chance to generate water.
(2) I believe Cargo Ships only places oil patches in deep water. This mod (mostly) only generates shallow water, because you shouldn't place deep water next to land, and it's hard to predict where the land will be for many patterns.

I'll leave a message on the Cargo Ships mod to bring this up.

Thank you for the fast response and looking into this for me! :D