What's the Name of That Book??? discussion

I read this book I the 1980's, don't know exactly when. Set in the modern day the story is about the search by a man who witnesses an abduction of a female office colleague by a gang of people/beings from a duel/alternative world based around the sea (old sailing ships) and deserted docks

Anything about the cover?
Location story takes place?
Part of a series?

How old were the characters? Could this possibly been a book for an older audience?

Any supernatural elements like witches, trolls, etc?

I can't remember anything about the cover. It started in the modern world with the kidnapping from an office block. The premise was that there is another world along side ours populated by shady characters. A world that we don't see or know about but can be drawn into. It's a world based on old sailing ships (say mid 18th century) that trade on the sea and have unseen docks within the modern docks. The world does not stray far from the sea and the raid on the office was unusual as it was a distance from the coast. The story follows a man as he learns and gets drawn into the shadow world in search of the woman. I don't believe it was part of a series just a stand alone book. The main characters were in their twenties and other than the shadowy people and the whole alternative world there were no particular supernatural beings like trolls etc.

Chase the Morning by Michael Scott Rohan maybe?

M, are you still looking for this or did you find it?

No response, moving to Abandoned folder.

M (OP) was last active on the site in February 2017.