First let me say I'm an automotive shadetree mechanic, but have no clue how to work on boat motors. Was at the lake and the motor was running great, then I got a rope tangled up in the prop. After that it would run OK at low throttle, but at WOT the prop was slipping. The engine ran fine but it wasn't applying all of the torque to the prop. In car lingo it felt like the clutch was slipping. Once again, I'm a novice so please talk in novice lingo. Where should I begin to look for the problem? Thanks for any help