I'm trying to track down the title of a great little gem that came out in the 1980's. The movie is about a boy, who lives with his father (I think a sister also),near a lake or a rock quarry. There is a local legend about a "Loch Ness" type of monster living in the water. The boy does some investigating and becomes obessed with discovering what it really is. After doing some experiments, the boy comes to a conclusion that a mechanical crane, that was used years back in creating a bridge, is what in the source of the "monster" legend. At the end of the movie, he dives and somehow gets stuck inside the jaws of the machine, and has to get rescued by his down and local authorities. I cannot remeber what the title of the film is or who stars in it. It came on HBO and The Disney Channel I believe. If anyone has any recollection I'd appreciate any help! Thanks!