A fine and a formal warning have been handed out to the skipper of a boat which capsized while crossing the Tairua bar, meaning he and his two passengers had to be rescued by emergency responders.

The men were not wearing lifejackets as they were required to when they were flipped into the sea during the March incident.

Police and bystanders retrieving the aluminium boat which capsized while crossing the Tairua-Pauanui bar on Monday. Photo: Claire Fitzjames/Fairfax NZ

One of the main nationwide rules is that people must wear lifejackets while crossing a bar.

Waikato Regional Council's maritime services team leader Richard Barnett says a formal investigation found the skipper was at fault.

'He has been issued with a $400 fine for failing to ensure life jackets were worn and given a formal written warning for operating a vessel in a manner which caused unnecessary danger or risk.

'The level of the penalties imposed reflects the lack of injuries sustained by the crew and the skipper's previously clean record with the council.”

Witnesses told the council the boat turned side on to the waves after an initial attempt to cross the bar.

The boat then capsized.

Richard says crossing a bar is an extremely hazardous activity.

'Because of the risks, we have worked with others to create a series of bar crossing videos for boaties. So there's plenty of information available via the internet about crossing bars, with a specific video on the Tairua bar. People need to do their homework.

'Boaties also need to make wise decisions about whether it is safe to go on the water in the first place and never try to turn mid-crossing.”

More information on how to cross bars safely is available at www.waikatoregion.govt.nz/barcrossing/

Waikato Regional Council's maritime services team leader Richard Barnett.