Situation: at sea in rough weather, fire sparks observed coming from the funnel; investigation shows the fuel contains considerable quantities of water and sludge. As Second Engineer:

1. Notify the Chief Engineer and the bridge immediately, recording the time and the problem; if there is a risk of further escalation, prepare to reduce load.
2. Stop/adjust the fuel flow to the engine and change over to a better-quality fuel (clean distillate or a different service tank) that is confirmed water/sludge-free, isolated the contaminated tank.
3. Stop the purifiers gently/safely to prevent water entering the fuel system; change the fuel filters (or renew filter elements) - the pressure differential will have risen; the filter will be full of sludge/water.
4. Bring in the standby/alternate service tank and Use the transfer lines to run on the good tank until the contamination is dealt with (purifiers refilled after draining).
5. Drain any water collected at the bottom of the service tank drains; the sludge/water separator will have collected water - drain the automatic water drain and clean the filters.
6. If the engine is running on badly contaminated HFO and the injectors/nozzles are blocked or the governor cannot hold speed, reduce engine speed/load to a safe minimum to prevent stalling.
7. Take the contaminated fuel out of the system - put the contaminated tank(s) on a quarantine line, drain the water, and arrange to separate/transfer the good fuel; the purifier and its clarifier to be re-run only after the water/sludge is dealt with (usually after stopping and cleaning).
8. Visually check the funnel/smoke and exhaust temperatures; if sparks persist or engine stalling occurs, stop the engine and have the injection/turbo cleaning and fuel system attended to; prepare standby arrangements.

The immediate aim is to prevent continued spraying of oil/sludge into the funnel (which ignites as sparks/soot) and to prevent engine damage.

1. Institute proper fuel management: routine draining and cleaning of fuel oil tanks, correct purifier/centrifuge operation (set throughput and separation temperature correctly), and routine inspection and change of filter elements.
2. Regular and correct purifier operation - maintain correct temperature, throughput and discard; carry out stand-by separators and keep the separator bowl clean; never operate with contaminated (watery/sludgy) tanks.
3. Daily/weekly rounds: drain all fuel tanks' water drains regularly, check fuel oil service tanks for water, check filter differentials, and log. Ensure the automatic water drain/separator on the fuel line functions.
4. Never allow water ingress: check for leaks in the steam tracing, fuel heaters, deck water, and any leaks between the fuel and water systems; ensure no contamination during bunkering - sample/top bunker quality, proper bunkering procedure.
5. Prevent mixing fuel types: keep separate tanks for different fuels; never let water-contaminated or sludge-laden tanks be mixed into service, and keep correct settling to remove water.
6. Maintain the fuel system clean: periodic cleaning of the fuel filters, heater, and lines; audit the on-board fuel specification and bunker analysis; check for oxidation/sludge build-up from ageing fuel.
7. Dispose of sludge correctly (sludge tank), never return sludge to the fuel system.
8. On the funnel side, good combustion by correct viscosity/temperature, and correct nozzle/atomization, maintaining proper scavenging so soot/oil does not ignite; keep the combustion and turbocharger clean.

The aim is to ensure only clean, dry, correctly filtered fuel reaches the engine so the stack remains clean and the risk of a funnel fire/engine damage is eliminated.