You only need to be licenced if you are on federal navigatable waterways. If your on a boat in a lake (like tapps for instance), and its under 16 feet with a propulsion system you dont require licencing...Lake Washington and the Columbia are a different story. You should however check regulations because I think there is a h.p. limit. I learned of all this the first time I went to Tillamook in my driftboat with a 7.5 Johnson on the back. It cost a 100.00 for the on water coarse. Much less if you take care of it on land.