rip rap is where the current hits the shore (usually a rocky shoreline)and deflects the current making a bunch of turbulance or “rip-rap”. the best example i can give is at baypoint in red wing just down-river from the no wake zone. that rocky shore line is considered rip rap.
i am not an expert on the topic but this is how i translate the term. hopefully somebody else will shoot their opinion on the subject.
I was always brought up learning that rip rap was old broken up concrete and rocks that line dams and other areas to prevent erosion and keep things in place. Those areas provide current breaks and places to hide that smallies love, as well as crappies, walleyes, and other fish. The rip rap also clears up the water in some areas, which make it more attractive to smallies. Throwing crawdad imitating cranks and plastics in these places can really be dynamite. Here are a few examples of rip rap that I could find on my pc real quick.
Down this way rip rap is anything along the bank, rocks and tree limbs and the occasional drunken fools that party along a favorite spot and throw cans and bottles in the water.