Experience Feedback
A large container ship was on a fixed trans-continental service, regularly crossing the ocean on a tight schedule. Every month, at the turnaround port, it was a routine for the engine crew to isolate, cool down and open the economiser (also known as waste heat or exhaust gas boiler) to clean out the accumulated soot and unburnt carbon particles. (Being very corrosive, these deposits can cause rapid wastage of the water tubes in the economiser and their eventual rupture. – Ed)
When sailing from this port, the first few starts of the very large marine diesel engine would eject clouds of soot from the main engine exhaust uptake. These particles would rain down on the bridge wings and external decks, often ruining the clothing of the unwary. Subsequently, after the outward pilot had disembarked and the engine was rung up on the sea passage (Full Away), the volume, temperature and velocity of exhaust gases would increase. By day, the soot particles would now appear like a continuous plume of smoke, (burning embers not visible) and, by night, it would appear as if there was a prolonged fireworks display atop the funnel. On many occasions, with a cross wind blowing, the fiery embers would be blown across the channel or fairway, and we would slow down or even temporarily stop the main engine to allow a terrified inbound oil tanker to pass. Generally, the exhaust would become clear after about 20 minutes’ steaming at full sea speed.
There were instances when the burning cinders would settle on the fabric roof or ‘soft top’ of open top containers stowed on the top tier on deck and burn holes in them. As a precaution, charged fire hoses would be kept rigged on the bridge wings and external decks and two seamen wearing overalls, boots, helmets and eye protection, would be constantly directing a fine spray over the area downwind from the funnel.
On one such passage, several slots in the last four cargo bays over the aft mooring winches were empty. It was around lunch time and the crew was in the messroom after having secured the pilot ladder. As expected, the exhaust appeared ‘smoky’, and unknown to the bridge watch, the strong head wind carried the sparks almost 100 metres astern from the funnel and deposited them on the exposed nylon mooring ropes wound on the storage reels of the mooring winches. The crew returned to the deck after lunch at about 1300 and noticed a strong smell of burning plastic. On reaching the aft mooring station, they noticed that one of the mooring ropes was on fire. The bridge was informed and emergency stations were sounded and the fire pump was started. The fire was put out within ten minutes but not before the rope had been completely destroyed.
Corrective / preventative actions
1. A fleet circular was issued to all vessels, listing the fire hazards arising from exhaust uptakes, especially after economiser cleaning and during routine soot blowing at sea, and procedures to mitigate the risks;
2. After every economiser cleaning, for the first hour after Full Away, it became standard practice to deploy an additional seaman on the upper deck, in radio contact with the two seamen already entrusted with the task of spraying the container tops from the navigating bridge deck with sea water;
3. Regional planning centres, contracted terminals and deck officers were instructed not to leave the container slots above the aft mooring station empty, especially when sailing from ports where the economiser had been cleaned;
4. Deck crew were instructed to immediately rig the protective covers over the mooring ropes once they had been wound on the storage reels of the winches.
Source: Mars/Nautical Institute