NEAR MISS !
The vessel was in Nigerian waters doing coastal run. She was light with permanent ballast and anchored off port Lagos. There was no record of cleaning low sea suction filter for nearly two years. So one fine morning I planned to do the Job. First opened all the hinged bolts one by one eased up greased and tightened back for easy removal of cover. All sea water valves shut tight including the isolating v/v of high sea suction. Cover vent cock of filter opened and welding rod passed thro’ to clear passage. Found not even a drop of sea water coming out from cock. Waited for a little while then started opening the hinged bolts one by one cross wise. Kept cover on two slackened bolts and eased cover by flat scrappers. Still no seepage of water from cover & body flange. Lifted cover about 20mm and found no water.. Assuming the v/vs, are holding good the cover was removed manually by four Nigerian crew members.
Now the tragic incident happened. The cover was kept aside, and filter was checked found dry and full of shells & sea weeds. After about 3 to 4 minutes all of a sudden full force of water started coming out like one meter dia fountain of ½ mtr height pouring out in to ER and I was stunned. I told the crew to put the cover back but in vain, and the cover was floating in the water force. 4 crew and my self stood on cover but could not bring it near enough to the body flange to put the hinged bolt in to the slot of the cover.
I did not panic because, I had been in Nigerian waters for quite a long time and I was aware that I can get shoree assistance in case of an emergency.
I asked 3rd Engr. & 4th Engr. to start main s.w. pump on low suction line and shut high suction. The pump pressure was fluctuating, but the water flow stopped and the filter became empty again. 2 pumps were on for pumping out bilges as it was already ½ mtr above tank tops. We cleaned the filter thoroughly and fitted back in place. SW p/p suction c/o to high suction and all v/vs on low suction line opened after venting of filter was and found all normal.
If the water flow would have continued in the same way, the bilge would be above bottom platform floor plated with in an hour. Thank god. He saved us it was near miss.
It is always better to keep the vent cock of sea suction filters open for much longer period if the is not cleaned occasionally.