To be honest with you, they just want your money, so just WALK into the DMV with that form filled out and see what happens.
If you are missing something they will tell you, you come back and that is it.
I have never done it but when I was contemplating buying an aftermarket hull I did some research.
This is from a DIY Sailboat forum, I am glad I save the posting as it is no longer there.
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http://www.messing-about.com
California (Frank Hagan)
California's Department of Boating and Waterways has a web site with the legal mumbo jumbo on it, but
they don't really clarify how to register a home-built boat.
I'll explain how you register a home-built boat to be in compliance with the Legal Mumbo-Jumbo.
The Department of Motor Vehicles (DMV) handles the boat registration.
The only thing they require is that you fill out form
Boat 101, available at
http://www.dmv.ca.gov/forms/boat/boat101.htm (thanks to John Wright in the rec.boats.building newsgroup for pointing out the correct form for me!)
On form Boat 101, you declare the value of the boat, which is the cost of the materials.
In California, you have to pay sales tax on any new vehicle purchases, so you have to show that you paid sales tax on the
materials to build your boat. I have over 100 receipts, but they were happy with seeing just 10 of the largest ones (for lumber, plywood, sails, etc.) that showed I paid state sales tax when I purchased the materials. Those 10 receipts were about 1/2 the declared cost of the boat.
Once they get the form and your receipts, they issue a state registration number, and two license tags that have to go on the boat.
They don't inspect the boat, they don't need to see a picture, they simply collect your money and give you the number. For a sailboat 16' long with a small outboard, with a declared value of $2490, the California DMV assessed a registration fee of $9. No kidding. Your local county is responsible for assessing the personal property tax portion of the bill (in my county, the county tax assessor sends a letter out asking for the value of the boat, and a picture, and they promise to send you a tax bill with your property tax bill. So far ... 3 years now ... I haven't seen the tax bill.)
If I hadn't kept the receipts, I would have had to pay sales tax on that $2490, which would have been many times the regular registration fee.
You also receive a HIN (Hull Identification Number) which must be placed on the starboard side of the transom, 2" from the deck, and either engraved, burned (yikes!), embossed or otherwise placed so that alteration or removal will be obvious.
Office Depot and other stationery stores sell brass nameplates that will work for this. I routed a recess in the transom, placed the plate in it, and covered it with a few thin coats of epoxy (and three coats of a clear varnish to protect the epoxy.)
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I hope this helps!
Benny