A 6m McLay boat with 4 people on board reported they had a flat battery and requested assistance.  The boat was midway between Whale Island and Raurimu Island.  Nightfall was eminent and the sea was calm with a 3kt SE wind. Whakatane Rescue was tasked to provide assistance and with a crew of three found the boat in the dark and provided a power pack battery unit to get the boat started and underway.  Whakatane Rescue followed the boat back to Whakatane and all arrived safely.