Upon arrival at Makarska, Croatia on 28 June 2024, three crew members remained on board the yacht Acceptus – the captain, the chief engineer, and one crew member. They immediately connected the shore power cable to the shore cabinet, thereby using the harbour’s electrical supply. Later that day, the crew noticed unstable voltage in the network, after which they switched to the yacht’s generator, while the shore power cable remained connected to the shore distribution cabinet.
On the same day, at around 11pm, passers-by noticed smoke at the aft section of the yacht. At the same time, the chief engineer, heard the fire alarm signal from the fire control panel. He immediately activated the general alarm, closed the fuel supply valves, and shut down the ventilation. All crew members abandoned the vessel.
Flames were initially observed in the technical area in the lower deck and soon spread to the adjacent underdeck spaces. Shortly thereafter, the municipal fire brigade arrived and commenced firefighting operations. The firefighters were unable to access the compartment where the presumed fire source was located. They therefore attempted to extinguish the fire by directing water from the shore hydrant into a small opening connected to the technical area.
The fire subsequently spread to the yacht’s hull structural elements, while at the same time, due to the additional weight of water from the hydrant, the yacht gradually listed to port until the port side rested on the seabed. Burning of the starboard side of the hull continued until the afternoon hours.
There were no injuries and no damage to nearby vessels, while the pollution was immediately contained and remediated by the competent authorities. As a result of the accident, the starboard side of the yacht that remained above the sea surface was severely fire-damaged, while the port side remained submerged, with the yacht resting on the seabed.
The wreck was towed to a repair yard, where it was recycled, and the yacht was deleted from the Register of Yachts of the Republic of Malta.
The investigation determined that the cause of the fire was the installation of untinned copper conductors and a poor connection between two segments of the shore power cable, which caused burning of the connection point inside the junction box. Therefore, the installation of a power cable of these specifications, along with the configuration of the connection point between its two segments, is a causal factor in this accident.
The following contributory factors were also established:
- The yacht’s power cable remained physically connected to the shore supply and energized.
- The use of an unapproved extension cable with unverified technical characteristics as an extension cable of the yacht’s power cable when connected to the shore distribution cabinet.
- The material of the junction box (PVC), which melted and initially spread the fire.
- The design of the cable ducts and cable routes without fire-resistant partitions and linings.
- The absence of a fixed firefighting system in the technical area and control room.
Two safety lessons were issued: the first concerns the technical safety of the design, installation, maintenance, and use of onboard systems, and the second concerning the necessity of installing fixed fire-extinguishing systems in technical spaces and control rooms. Two safety recommendations were issued to the classification society.
Based on the results of the safety investigation into the marine casualty of the motor yacht Acceptus and following the analysis and conclusions of this report, the Agency for the Investigation
✓ AIN05-SL-2/2026
Safety Standards of the Electrical Installations on Vessel
Electrical installations are a frequent source of fires. Therefore, the proper design, installation, maintenance, and use of onboard systems are essential for the vessel’s fire safety.
Cables installed on vessels must be technically compatible with the corresponding systems, but even more importantly, they must be suitable for the specific environmental conditions in which they operate. For the safety of the vessel, it is important to use only cables specifically designed for marine and shipboard applications.
The key difference lies in the conductor construction – marine cables use tinned copper wires, which significantly reduce the risk of corrosion at the connections and within the conductors themselves. Cables must also have appropriate insulation that does not support combustion and serves as fire-resistant insulation.
All power cables must only be connected inside junction boxes or cabinets with enhanced protection levels. Even in this case, connection points within the cabinets must be further protected with coatings against condensation and salt retention from the air. Elevated protection of distribution cabinets does not guarantee complete safety against the ingress of air, and thus moisture and salt. These substances deposit on surfaces after evaporation, creating hygroscopic layers that attract additional moisture.
Junction boxes must be made of materials that can prevent, or at least effectively slow down, the spread of flames originating inside them. Additionally, various technical solutions can be applied to reduce the negative impact of the marine environment, such as anti-corrosion sprays, boxes with controlled internal overpressure, and similar measures. Since these locations can be sources of sparking, regular inspections must verify the tightness of screw connections, not only mechanically but also by checking for conductor pull-out resistance.
When not used for power transmission, the shore power cable must be physically disconnected from the shore distribution panel to reduce the risk of voltage effects on damaged or degraded parts of the cable.
Cable routes should be installed according to class rules, providing adequate fire protection, with the aim of preventing the spread of fire. This applies especially to cables intended for the high-power transmissions, from one panel to another, or to larger consumers.
Such routes should be enclosed, and all cable penetrations through bulkheads must be executed using protective barriers, in accordance with the manufacturer’s instructions. Routes containing cables of different voltage levels must be separated by a safe distance.
Any additional interventions on the electrical installations must be carried out by authorized personnel, with the knowledge and approval of the classification society. The proper installation and operation of the electrical system must be checked during the vessel’s construction and throughout its service life.
Recipients: This safety lesson is intended for classification societies, flag state maritime administrations, yacht owners and managers, yacht crews, charter companies, and port authorities managing marinas and yacht harbours.
✓ AIN05-SL-3/2026
Fire Protection of Technical Areas and Control Stations
Fire protection must primarily focus on prevention. However, if a fire does occur, it is essential to ensure that flames cannot spread rapidly and that the fire can be brought under control as effectively as possible.
This is achieved by dividing the vessel into fire zones, using fire-resistant bulkheads and fire doors, implementing early detection and alarm systems, and installing fire-extinguishing systems.
Fire-extinguishing systems include:
- – Initial-phase firefighting devices (e.g., portable fire extinguishers, sprays, and passive systems in transparent containers that release their contents when exposed to high temperatures—particularly suitable for electrical cabinets).
- – Developed-fire suppression systems, such as sprinkler systems, water mist systems, CO₂ systems, NOVEC 1230 gas systems, and similar technologies.
Apart from the engine room, which is particularly critical due to the equipment and flammable materials present but is usually adequately covered by fire protection systems, attention must also be given to other spaces that require additional fire protection. Areas containing significant electrical equipment, fuel, or hydraulic oils should be equipped with fixed fire-extinguishing systems (automatic or remotely activated). Early activation of these systems can significantly improve the chances of successfully controlling a fire on the vessel and may even fully extinguish it in its initial stage.
The installation of such systems is especially important on vessels with sandwich-structure construction. When flames and high temperatures reach the inner layer of the structure, the suppression of the fire spread becomes extremely challenging, as the outer, non-combustible layer insulates the flammable core from the action of fire-fighting agents.
Recipients: This safety lesson is intended for classification societies, flag state maritime administrations, yacht owners and managers, yacht crews, charter companies, and port authorities managing marinas and yacht harbours.
Safety recommendations are intended for those recipients who are most competent for their implementation, with the aim of preventing future accidents and incidents and improving safety in general. Safety recommendations in no case create a presumption of liability or blame for the accident.
Based on the results of the safety investigation of this accident, and derived from the analysis and conclusions of this report, the Air, Maritime and Railway Traffic Accidents Investigation Agency issue the following safety recommendation:
✓ AIN05-SR-2/2026
It is recommended that RINA Classification Society amend the Rules for the Classification of Yachts so as to extend the existing requirements for fixed firefighting systems of appropriate specifications in technical areas and control spaces containing highly flammable materials and liquids to all yachts, regardless of size.
✓ AIN05-SR-3/2026
It is recommended that RINA Classification Society amend the Rules for the Classification of Yachts to require high-capacity power cables on yachts to be installed exclusively within enclosures and cabinets constructed of materials that effectively limit the spread of flames originating within them.