BEWARE - ICE PIECES :
Vessel was doing river passage in St. John Canada in December 2005 during winter and sea water temp was about -10oC. Pilot had warned us that sea suction filter may get blocked due to ICE pieces entering it. So sea suction steam heating was kept open. But after some time MSW pump suction pressure started coming down. Both M/E & A/E J.C.W temperature started rising. Opened and cleaned the suction filter of the running S.W. pump after starting stand by pump. But within few minutes noticed pressure of the pump also coming down. Again changed over pumps.
After this every 5 minutes changing over the pumps and cleaning filter became necessary to keep the engine going. Since this was creating tension unnecessarily, informed Master, about the problem and requested for stopping the engine, to make some alternate cooling arrangement for A/E, for which the temperature was shooting up fast. Engine could be stopped after 20 minutes only. After stopping the engine pressure came up because only while V/L was under way the ice pieces were drawn in with such magnitude.
External sea water connections were made to one of the generator and this was connected to the fire line. Fire pump was not drawing in much ice by virtue of its location. After this modification we coursed the remaining river passage without any incident.