Abstract: A theft protection device which will protect either a docked boat or a parked boat mounted on a trailer includes a control box which houses electronic circuitry and batteries for energizing an audible alarm when the boat's battery cable or a cable connecting a lock box to an anchoring post is severed. The lock box completes an electronic circuit which is integrated with the electronic circuitry in the control box and includes a pair of shackles which receive a key operated lock which may be adjustably received on the shackles.