Original Oil Painting with Ship signed "Rietberg" or "Riatberg"

I found this painting at a thrift store for $100.  It is an original painting (looks to be oil) and is painted on a Viktoria Maltuch canvas.  It is about 30" x 40" in size and is signed in the lower left hand corner (picture of signature included) as either Rietberg or Riatberg.  I'm having a hard time finding any information on the artist, the time period (although it looks late 19th c.-early 20th c.), or any other information about this piece.

I've done a Google Images look-up to no avail.  A major problem I keep running into is that there is a Rietberg Museum in Germany that houses art galleries, so this seems to keep coming up on every search.  

If you have any information about this piece, or, if you think the investment of $100 was well worth it, please let me know....it will be greatly appreciated!

Regards,

Rick

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