yes, you do, even an electric motor on a boat would need to be licensed..

federal waters here include

Puget Sound

Lake Washington

Hood Canal

Lake Union

Sammamish

Columbia River

Snake River

Yakima River

Pend Orielle

Capitol Lake

and a few others i cant remember, i think American may be Federal too, but not sure..

i think its everything affected by tide, is Federal Waters, and you need to be licensed if you are using any method of propulsion, and i think sails are part of that, but not 100% on that...

i would contact the USCG for further clarification of what bodies of water are classified as Federal in this state, because i know i missed a few..