Maersk Rio Bravo berthed at Port Chalmers yesterday. The size of the ship and the cargo it was loading forced the ship to run a second and unsilenced generator. Port Otago chief executive Kevin Winders said as soon as the second generator started it made a noise. With meat products, a second generator was needed to keep the cargo at a specific temperature. Yesterday the wind was blowing from the north, directing the noise straight at the Port Otago office and down the harbour towards Dunedin.