When the Strait of Hormuz opens for safe passage, vessels may face operational risk affecting the fuel systems, hull condition, and anti-fouling performance. Proper inspection and mitigation are required before resuming service or operation.

Fuel system

Extended idling, especially in high-temperature or tropical regions such as the Arabian Gulf, can lead to significant fuel degradation, water contamination, microbial growth, and sludge formation, increasing the likelihood of machinery damage, operational delays and insurance claims. Extended storage of fuel under heat and inactivity accelerates the fuel instability. Key risks are microbial contamination, sediments and sludge accumulation, fuel oxidation, and water contamination from condensation and wax precipitation.

Some operational risks of failing to control fuel quality include filter clogging in the fuel system and purifier failure.

To mitigate the risks, a fuel quality test is recommended. The vessel should obtain representative samples from all fuel storage tanks (top, middle, and bottom). The test should be carried out for water content, microbial contamination, fuel stability, and sediment levels. Proper tank and fuel management should be carried out, including draining all settling and service tanks for free water and sediments. Inspection of tank vents and air pipes for any moisture ingress should be carried out, and biocide treatment performed if microbial contamination is detected. Fuel polishing systems to remove any suspended solids and water should be utilised. Machinery needs to be checked as well, including cleaning or replacing filters and strainers, and verifying the operation of heaters and viscosity control systems. Running the fuel purifiers in recirculation mode before engine start should also be performed.

Hull condition

Vessels with an extended idle period, particularly in warm or tropical waters, lead to marine growth such as slime, algae and heavy barnacle accumulation. This will result in increased hydrodynamic resistance and, in the worst case, blockage of seawater intakes.

To mitigate the risk, we recommend conducting an underwater inspection to assess hull fouling, sea chest integrity, and the cleanliness of the rudder and propeller. If the fouling exceeds the acceptable levels, cleaning is necessary. Use only the approved cleaning techniques to avoid coating damage. The vessel needs to monitor speed and engine load during the initial voyages closely.

Hull performance directly affects fuel consumption, and it is important to keep the hull clean and maintain the specialised coating to reduce overall energy consumption.

Anti-fouling coating performance

Prolonged vessel inactivity will result in reduced coating activity, accelerated fouling, and potential coating degradation. Self-polishing and ablative coatings require vessel movement to remain effective.

Inspections should be carried out to check for uneven polishing, flaking or blistering, and localised corrosion.

If required, we recommend gentle cleaning to preserve coating integrity and resume operation with a progressive speed increase to reactivate coating functionality, where applicable. If coating performance is severely compromised, plan for dry-docking.

Members may contact Skuld’s Loss Prevention / Technical department for any clarification on this advisory.