An 18-foot Canadian-registered boat caught fire last evening shortly after 7:00 p.m. south of the Blue Water Bridge in the St. Clair River.  Four people and a dog were aboard the boat at the time of the blaze.  Those aboard were able to put the fire out before rescue crews arrived.  The boat was towed to the Canadian side of the river.  Port Huron Fire Department,  St. Clair County Sheriff Department dive team and the U.S. Coast Guard responded to the scene.  No injuries were reported.