We consider the situation of a boat pinned or wrapped against a rock by moving water in a river. The force exerted by moving water is calculated and the force required to extricate the boat is estimated. Rafts, canoes and kayaks are each considered. A rope system commonly employed by river runners to extricate a boat is analysed. This system includes a mechanical advantage z-drag and a self-equalizing tie-off, and the tensions in various parts of the system are calculated. Introductory undergraduate physics is used throughout this work.