Shark vs Boat in Australia

Me and Allan went fishing about 8am off a local beach blacksmiths, after about 2hrs on the water about 15 kilometres out to see a large shark approached, and almost immediately started circling the boat then it started to get more aggressive nudging the boat. it went on for about 5 minutes and the shark got more aggressive as it went on. after the video we went to start the engine and it failed the shark went for the engine and nudged it whilst I was trying to start it. then it started and we took off.