this could be due to the movement of the vessel due to heavy weather, which might have disturbed the water lying in the bottom of the service tank below the suction and caused it to mix with the oil in the lower part of the service tank.

• Drain the settling and service tanks frequently to remove accumulated water.
• Run two purifiers in series at minimal throughput to maximise water separation from the fuel.
• If high and low suction points are available in the service tank, change over to the high suction line to avoid drawing water from the lower layers of the tank.
• Divert the return line from the engine to the settling tank instead of the mixing column to remove the remaining water in the fuel system quickly.
• Operate back-flushing filters continuously to prevent clogging from contaminants. Do not reduce the engine load, as this may worsen misfiring and lead to stalling. If the engine stalls, restarting would require flushing the entire fuel system.
• Check for potential issues like leaking sealing water, incorrect gravity disc size, or malfunctioning water detection systems.
• As a last resort, switch from HFO to low-sulfur gas oil (LSGO), which is less likely to have water contamination issues.

• Fuel bunkered with excessive water content due to poor quality or improper testing can introduce water into the system.
• Leaks in the purifier sealing water, an incorrect gravity disc, or faulty water detection sensors can allow water to pass into the fuel supply.
• Damaged steam heating coils in bunker, settling, or service tanks may allow condensate to mix with the fuel.
• Corrosion or structural damage to the tank top can cause water ingress, especially during heavy weather.
• Corroded or sheared vent pipes at deck level can allow seawater ingress during rough seas.
• A ruptured ship side or cracks in double-bottom tanks can lead to seawater entering fuel tanks, especially in older vessels.

• While receiving bunkers, a sample must be tested onboard for the presence of water. If water content is found to be above 0.5%, then extra attention should be paid to ensure purifiers are removing water efficiently.
• Maintain settling tank temperature above 70deg C and service tank above 90deg C as this will allow water separation.
• Every watchkeeper must drain the settling and service tanks during their watch to remove any accumulated water.
• The purifier is to be continuously operated, and when the service tank is full, the overflow should lead to settling tank and the fuel to be circulated to enable efficient purification.
• The purifier is to be operated with the correct size of gravity disc. This can be found by checking the fuel analysis report from the laboratory, and the relevant gravity disc can be found in the purifier manual.
• The duty engineer should check the purifier while in operation and also monitor the desludging cycles to see if it is operating correctly.
• Check steam heating coils in all tanks for leaks or damage. Ensure drain water does not show signs of oil contamination, as this indicates potential steam coil leaks.
• Inspect vent pipes regularly to ensure they are intact and properly sealed to prevent water ingress during rough seas.
• In case of any doubt or if water content is found to be more in any situation, call me immediately.