Fishing line in props...

[tautog]

Must be luck of the draw with prop damage as a boat like the Paramount must collect about a hundred yards of braid per trip.

[Captain Rich]

Tog- It's not the props that suffer, the line will dig into the cutlass bearings and ruin them causing shaft wobble, or wear into the shaft as Jerry mentioned and either cause wobble or weaken the shaft to the point that it is unreliable. If there is minor scoring the shaft can be "splatter welded" and then lathed, if there is deep grooves then the shaft has to be replaced.