Shark circling our boat while fishing

This happend half an hour off shore from Blacksmiths beach. We were out fishing when this shark started circling our little boat. It felt like getting trapped in a room with an angry pit bull. he just wouldn't leave us alone. it actually nudged the boat (there was some blood in the boat that was washed in and out) . at one point i tried to pull start the engine and it came right underneath and head butted the engine while trying to open its mouth. Scary and owe inspiring.