A passive security system and personal equipment on vessels is for man over board situations. The personal equipment, prepared for being worn by a crewmember of the vessel, includes a first module (2) integrated into a belt (4); a life jacket (5) folded inside of the first module (2) and attached thereto by at least one strap (6); a second module (8) placed in the interior of the first module (2), connected to the life jacket (5) and configured to inflate the life jacket (5) when it detects a man over board situation. The first module (2) has on its rear part one flap (3) configured to be opened by the life jacket (5) inflating action, allowing the passage thereof to the exterior of the first module (2). It is used as a passive security element for “man over board” situations, to allow an immediate detection of the situation and a fast rescue.