Help with identifying an artist

I have a pretty old what seems to be a watercolor in a heavy wooden frame. Paper on the back is glued to the frame so I'm hesitant to take it apart to remove the picture itself. There is a signature in the very lower right corner that says "A.Th"...there is more to the signature but it is hidden behind the frame. It is a rocky shoreline scene with small fishing boats and is done all in gray and white shades giving the impression it is nighttime.Pic of signature added here.