I believe the one-time vessel use permit is $500, and after the 12 months you then can't return to Washington for 24 months.
There are other options, see
http://dor.wa.gov/docs/Pubs/WatercraftVesselTax/BoatBroc.pdf
That's right. Pay careful attention do the do-not-return clause, especially if you plan to travel south again after your year is up.
And all the other rules and regs may seem straight forward, but if you are coming and going in and out of the state over a year or more, the rules suddenly become a lot less clear, the state's permitting procedures appear contradictory to the actual laws, and you will get completely conflicting info from state officials if you ask.
I finally gave up after finding it impossible to determine how long I would remain exempt, and left for Canada. On our return south, we won't/can't stop in Washington. It's a lose-lose for everyone. I don't get to enjoy Washington, Washington bushiness lose my business, and the state loses the tax revenue on that business. And of course the sate doesn't get the use tax either. The only winner is Canada.
A friend of mine visiting from Australia went through the same run around, along with countless other people I know.
Nobody likes taxes, but I accept they are part of our society, and I'm happy to respect any jurisdiction's tax structure. But it needs to be clear what the rules are so I can comply and/or decide whether to visit and how long. Washington's rules are such a murky mess, and the use tax is so high, it's just too big a risk to do anything other than visit for the allowed 60 days a year, then leave.