I have a 1975 Bayliner Admirality 2050 Cuddy with a 5.0L Ford Inboard V-8 and an OMC drive unit. I was out on the lake for about 3 1/3 hours pulling tubes...fishing, etc, and on the way back to the public launch the engine started to smoke, and I noticed the temp guage was at 240. I had been running hard all day with absolutely no problems. I immediately shut the engine down. I was told that the impeller was what failed. I know nothing about boats, and I am in desperate need of ANY advice. Thank you ahead of time...