‘‘Nice boat,'' he says, with just the right note of respect and admiration.
There are faster, bigger and more expensive boats on Lake Wanaka, but Swan Song is the one that gets the smiles and the compliments.
Mr Duncan says the boat looks good, smells good and goes well on a flat lake.
But, he does not hesitate to point out some of the more trying features of his mahogany-clad 1930s-style ‘‘woody''.
There is the need to use an extra long drawbar to float the boat off and on the trailer, to avoid damage to the hull.
There is the small rudder, which makes steering more than a little vague at slow speeds.
The lack of a canopy is noticeable when the sun beats down.
And, when the Duncans are not using the boat, there is always plenty of minor maintenance to do.
Not that Mr Duncan minds in the slightest.
Mrs Duncan said it took her husband months to decide to drill a couple of small holes in the mahogany deck so he could fit two period-piece air horns.
She recalls, with a laugh, that when Wanaka had an earthquake earlier this year, she found her husband steadying the boat in the barn, oblivious to all other potential safety concerns.
Their barn, incidentally, was built to fit the boat.
Mr and Mrs Duncan describe themselves as the boat's ‘‘stewards'' rather than its owners, aware it is a piece of craftsmanship they are responsible for passing on in good shape.
Not that it will be leaving the Duncan family.
Swan Song is the last boat built by Jack Ryan, of Ryan Custom Craft Boat Builders in Christchurch, and when Mr Duncan bought it in 2000, he gave Mr Ryan the undertaking he would keep it in the family.
The boat, though inspired by the designs of the 1930s, is only 16 years old and has many of the mechanical features of modern boats.
It has a kahikatea frame, and plywood hull and deck overlaid with 9mm mahogany planking.
It has a V6 Holden/Buick motor and a 270mm brass propeller.
In 2005, it was judged best powered craft at the Lake Rotoiti Antique and Classic Boat Show.
Swan Song had outings on Christmas and Boxing Days, but is back in the barn again until the holidays are over and the lake is a little less crowded.
