OOPS, I got a line around the prop.
There it is, the spot you have been looking for all day. You drop your bow anchor and start to back down to set it. Suddenly the engine stops abruptly. "What theeeeee, OOPS I forgot to pull in the dinghy's painter line." Before you jump over the side, ease the boat in forward gear, this could unravel the line. If that doesn't work, try putting a pipe wrench around the shaft inside the boat and turn the shaft in the opposite direction of the wrap while someone on board pulls on the line. If not, you'll have to dive and cut the line free.
Don't forget to remove the key from the ignition.