On a hunch, based on general characteristics I could see in your photos, I checked my earlier files and found your painting. Dated July 27, 1973, it would be among the paintings I did on my first year living full time in Ephraim, taking up full time painting after some 20 years of collegiate teaching.
The title is "Schooner Augustus", a full size watercolor (21 x 28), sold to Art Kelm in August of 1973 for $300, paid for on the installment plan by June of '74.
The painting has my early, confident vigor in style. The ship is a Great Lakes schooner sailing southward past the bluff at Ephraim and into the Strawberry Channel on Green Bay heading toward ports to the south like Sturgeon Bay or perhaps Green Bay itself. I'm not sure where I found details for the Augustus, but she looks typical of the class of commercial carriers hauling lumber and general produce in the 19th Century, and I have a vague memory that she was a Green Bay vessel. I do remember doing commissioned work about then for a Green Bay shipping company.
I don't have first hand experience with secondary market values, though a lot of my old paintings have been sold in local galleries over these last years. My guess would be something in the $3000 to $4000 range if it is in top shape.
Thank you letting me review your painting; I enjoyed it. Charles Peterson