Seventy-seven entries have been received in the Green Fleet championship, which is for the up-and-coming open fleet sailors.
The championship is held every year at a different sailing club throughout the country.
Toyota New Zealand's association with the event dates back to 2000 and has the backing of the "Believe" programme.
Kylie Cotton, sponsorship manager for Toyota NZ, said the company helped sailing clubs host such world-class events as the one in Napier so that aspiring sailors could receive valuable racing and coaching experience.
Several elite optimist sailors from the country are vying for a place in the national team for the Optimist World Championship, which will be held in Malaysia at the Royal Varuna Yacht Club, near Bangkok, in July.
The team has five places and the nationals here will be the deciding regatta to secure the berths.
The nationals finish on Tuesday next week.
A teams' racing day will be staged this Sunday.
The Napier Sailing Club hosted the Flying Fifteens World Championship last month.