A yacht skipper who forced a container ship to change course in the Tauranga Harbour entrance has been fined by the Bay of Plenty Regional Council Harbourmaster.

The incident occurred on June 5 as the container ship was coming into the Port of Tauranga in the Matakana channel.

The ship tried repeatedly to alert the yacht with five short blasts of the horn, with no response or alteration of course from the yacht. The ship was forced to change its course.

Under the Regional Navigation Safety Bylaw, a skipper of any vessel under 500 gross tonnage within the Tauranga pilotage area can not impede the navigation of any vessel over 500 gross tonnage.

Harbourmaster Jon Jon Peters said there was a moving prohibited zone in the Matakana channel to help protect smaller boats.

"This means skippers must not navigate 500 metres in front of and 50 metres either side of large ships," Peters said.

"We had a patrol boat in the area and the skipper of the yacht was spoken to after the incident."

Under maritime law, the skipper has been fined the maximum amount of $200.