"Imagine sitting in the RailCruiser with nothing ahead of you but the unobstructed curve of the rail stretching out into the distance, the countryside drifting by and the clickety clack sound of the rail beneath you," he said.
"To date the only way to come close to such an experience is to ride in the cab of a train locomotive, however not many people have been lucky enough to.
"It is this kind of unique experience that inspired RailCruising," he said.
"It's the freedom of being on the rail and going somewhere but not caring, just enjoying the ride."
The RailCruisers will run about 250m apart in one direction to the destination railway station where they will be turned around, ready to return.
Mr Oppatt said the venture would make good use of a previously unused, deteriorating railway line, adding value to Rotorua as a tourist destination.
It also opened the way to save other abandoned lines, he said.
"The world is full of abandoned railway lines which, together with a huge worldwide tourist interest in railway journeys, makes RailCruising the ultimate rail experience."
The longest RailCruising excursion will be the Mamaku Outback, an 86km return excursion from the Rotorua Railway Station to Bart's Crossing, Ngatira near Putaruru.
Next year the venture will introduce RailBiking, on the Rotorua to Ngongotaha section of the track. RailBikes are four-seater pedal-powered rail vehicles, for more energetic customers.
With work now being done to make Lake Rd into four lanes, Rail Riders planned to develop a new Rotorua Railway Station beside the railway line at the junction of Lake and Railway roads, Mr Oppatt said.
This would be the headquarters and main booking office for RailCruising and RailBiking.
Other railway owners in New Zealand and Australia had already approached Rail Riders with a view to establishing RailCruising on their lines.
Mamaku Express had been operating for a month and there were future bookings coming in, including quite a few from cruise ship vintage car enthusiasts and railway groups, Mr Oppatt said.
Although there was huge potential for the venture in the Asian tourism market, the domestic market was also very important, he said.
It would take time to build up numbers and a reputation within the tourism industry but Mr Oppatt expected RailCruising could become Rotorua's iconic tourist attraction.