Use the Happy Troller to slow big motors to a fish tantalizing speed. The Happy Troller locks in the down position for trolling and locks in the up position for cruising. You can use Happy Troller year round in fresh or salt water. It stabilizes bow-light boats and installs in 15 minutes. The large Happy Troller fits I/Os plus all outboard motors 50 HP and larger. The small Happy Troller fits outboard motors 20-50 HP.