Despite a fifth placing with Polyatomic in race eight, Mr Ralph held his lead, taking home the top prize and leaving Mr Pender in second place with the $1500.
Mr Ralph said the wet weather had suited his horses.
He had been training them since early January and said he had waited for the Autumn competitions because they raced better on wet tracks.
Racing Tauranga put on the cash competition to try and attract more entries to the the Bayleys International Japan New Zealand Raceday on March 22, and Saturday's Carnival, with the winner judged over both weekends.
President of Racing Tauranga Roger Hills said Autumn was a tough time to get entries.
"At this time of year it is always a struggle for horse numbers with the change from summer and winter horses racing."
Despite the attraction of the cash prize, there were also a lot of scratched entries due to the severe weather leading up to the weekend.
TRAC general manager Jen Evans said the trainer competition was a highlight, coming down to the last race as the decider.
"This competition really made the day. It added a lot of excitement," she said.