I’ve had many canoes over the years. Cedar Geislers, Fiberglass Old Town and a Detroit Boat Works canvas that dates to 1910. A few years back I bought a 17’ Grumman with two factory installed wings at the water line. It has a square back for a motor. It is heavy! I have spoken to Marathon boats in New York state but they have no records of ever making this kind canoe. I even spoke to an employee that worked there back in the Grumman days. He said he kind of remembered some experimentation that was going on in the 1950’s or 1960’s with this type of craft. It rides well and is very stable. I sure wish I could find out more about it. It’s an attention getter and my outing always take extra time to show folks this unique craft.
What you have may be a Grumman Sportboat. It looks like a squaresterned freighter canoe with flat bench seats. They had the spray deflectors along the sides that helped reinforce the transom area.