RedactedNarrative: On July 15, USCG Sector San Diego initiated a Critical Incident Communication (CIC) conference call after receiving notification of a 50 – foot vessel engulfed in flames five nautical miles offshore Carlsbad, CA. Oceanside Harbor Master confirmed a live aboard recreation vessel matching the size description that was not in its usual slip. USCG San Diego was able to obtain a contact name and phone number for owner. Cell phone trace confirmed the location of the owners phone was in the position of the vessel fire at initial report. Oceanside Harbor Master stated the vessel is a single live aboard, unknown of any tender or dingy associated with the vessel. Owner was seen departing the harbor this morning on the vessel. The vessel has sank in 1800-feet of water. Debris visible on the surface with reports of a small sheen. It is unknown how much fuel was on board. Next of kin have not been located.