This year, event co-ordinator Stephanie Rush said they decided to host one large field, made popular by the Armada Cup in Switzerland.
Armada Cup is unique in that it has a mass start with lines of 25 boats stretching across the river.
It is more inclusive and also reduces the production costs by having one giant race as opposed to a main event with several support races.
"Single scullers are invited to compete on the Whanganui River, going head to head against Rowing NZ summer school elite athletes, including Olympic champions Drysdale, Murray, and Hamish Bond," said Rush.
Bond was the only gold medallist unable to attend in 2012, due to his girlfriend's graduation.
While single scullers of all levels will compete together, Rush said there will be prize purses for winners from each category - elite men, elite women, club, masters and school.
"The extra participants should provide an exciting spectacle for the crowd."
Drysdale, a five-time winner of the Armada Cup, welcomed the change.
"This is an awesome race. It's unique in the fact the scullers all start together in a shotgun start.
"It's carnage and a big advantage to be in front."
He last entered in the Swiss cup race in October 2013, finishing tenth overall, over a minute behind local winner Nico Stahlberg.
In addition to the Billy Webb trophy race, there will be the Corporate Eights Challenge, which will feature heats in the Aon Jury Cup Regatta on Saturday, November 29, with the final on the Sunday.
The Billy Webb Challenge commemorates world champion Billy Webb's historic defence of his title on the Whanganui River back in 1908.
For more information, visit www.billywebbchallenge.co.nz