Cal. Veh. Code § 9845
The director, deputy director, registrar, deputy registrar, investigators of the department, and peace officers, as defined in Chapter 4.5 (commencing with Section 830) of the Penal Code, may inspect the hull identification number, certificate of number, and certificate of ownership of any vessel, as defined in Section 9840, when transported on a highway, or in any public garage, repair shop, public or private marina, dry storage facility, new or used vessel sales lot or boat yard, or other similar establishment for the purpose of investigating the ownership and registration of vessels, locating stolen vessels, and for inspection of wrecked, dismantled, or abandoned vessels. The authority to inspect pursuant to this section does not extend to any enclosed living area aboard a vessel.
Ca. Veh. Code § 9845