A trenasse is a small waterway in the brackish marsh, important to trappers for gaining access to furbearing animals. Some trenasses are natural, but many are created by people, often using a homemade craft like this one. Rotating blades in front, powered by a large automobile V-8 engine, bite into the marsh and pull the craft forward, creating a waterway 4 feet wide and about 2 1/2 feet deep, adequate for the pirogues that use it.