Years ago had a canoe blow off...it was one of those coleman red plastic ram-x things. Just stopped, drugged out of the ditch and tied it on better
My boyfriend had that happen with a friend's canoe last summer. Big old plastic thing that cost them $75 thirty years ago. Somehow chewed through a strap and flew off on the highway. Put a crack in the bow, but we patched it up with Splash Zone epoxy and it holds water just fine. They don't use it anymore anyways, so they let us have it in exchange for us supplying pallets for the big New Year's bonfire, which we do regardless. Not a bad deal.