A group of whale watchers got more than they bargained for over the weekend. Passengers onboard a SLO Tours charter boat received a head-bump from a 16-to-18 foot great white shark. The boat was about three miles offshore when the shark bumped the side of the boat. The tour company shared the video on its Instagram page. No one was injured in the incident. Wildlife officials say great white shark sightings on the Central Coast are common. Attacks are rare.