As a former Washington
resident, I will offer only what I believe to be true and you can verify, then decide how it applies to your situation.
Vessels registered in their home state are allowed to be used for 60 days from the date of their arrival without permit. If the vessel is going to be in Washington
for longer than that, an additional 60 day permit may be secured from a DMV licensing office. This must be done prior to the original 60 days expiring. To obtain that permit, a current registration
from the the home state must be presented ( they will not give an extension on an expired registration). If the vessel is intended to be in Washington for more than 120 days, it will need to be registered with the state and wear WN registration
Note that if you are planning on mooring
in Washington waters for more than 30 days, you will need to provide the marina with a copy of a Vessel Registration Exemption form. This form is available online at:
I hope this helps-