Is a documented vessel exempt from state jurisdiction?

No.

Any documented vessel must comply with the laws of the state in which they are operated, including the laws relating to safety equipment, according to the Government. 

Upon demand, the vessel’s Certificate of Documentation must be shown to state law enforcement.

Depending on the state, documented vessels may be required to display state decals detailing that they are in compliance with state requirements. Additionally, states may necessitate documented vessels to be registered but not state numbered.