There has been a couple law suits against the state about personal property tax on boats registered in AZ, stored in AZ and only used in AZ, and as far as I know, the state can still tax you for the boat if your work in Cal, your income is Cal, and your PRIMARY residence is Cal.

However, if the boat is registered in Cal, your are already paying that personal property tax thru the registration fees, and it makes no difference where you store or use the boat.
If you think you can dodge the tax by registering it in AZ and only using it in AZ, just hope they don't find out. And they are actively looking.