Even in moderate winds on smaller boats, the force of the boom when jibing can be deadly, let alone potentially damaging to the rig. Although inexperienced crew or guests are especially at risk, knowledgeable sailors have also been killed or injured in jibing accidents. If you want to sail downwind without worrying or having to set up a preventer, the Dutchman Boom Brake is for you.
The Boom Brake uses the same principle as a line wrapped around a winch to control side-to-side boom movements. Under tension, the boom brake works like a preventer. Ease the tension, and the boom swings at a slow, controlled rate. With the tension off, there is no effect on the boom's movement, and tacking upwind is not affected. No more near misses or worse, because the boom never has a chance to speed up to dangerous velocities.
The boom brake uses a line (not included) run from the chainplates to the brake. You regulate the boom speed by adjusting the tension on the line.