What Would You Do?

[JK]

The ship bunkers in the afternoon by truck to 80% capacity, then sails.

She's about 90m in length, 20 m breadth. Has 4 double bottom tanks, 3 sets of wings, one set and day tank. The fuel tanks all have overlow lines at 98% to an overflow tank, which is alarmed at LL and HL. The overflow tank is either pumped through the FOP or the FO transfer pumps.
The fuel tank valves are hydraulic quick shut valves. The wing tank quick shut valves are located in the pipe tunnel and there is a manifold in the forward engineroom.

It is a coastal job, and about 2300, the ship is anchored along the coast. Given the direction of the wind the ship lies broadside to the waves, and just out past where the ship is anchored, there is an underwater shelf which increases the height of the waves quickly. The end result is the ship is rolling very heavily at anchor for about 4-5 hours, until the old man gets tired of it and rings for engines,

The on duty watch is plagued with the overflow tank alarming and they spend most of the watch pumping from this tank to the other tanks. It is so bad, that if the tanks had been pressed,there would have been a fuel spill.

The next morning the oiler sounds tanks at Noon as usual.

What did he find?
What should have been done during that night watch?
What was the defect found that caused the problem and what was done to address it?

This is an actual happening.

[Big Pete]

I can envisage 2 different scenarios:-
A)
1) I suspect the oiler found that the bunker tank levels had gone up.

2) When the overflow tank went into alarm, ideally all the bunker tanks should have been sounded in order to determine where the oil came from, however that is the ideal answer in an exam, I probably wouldn't have bothered until the second, or even the third time the overflow tank alarmed, even then it may not have been practical to get accurate soundings with the heavy rolling.

3) I suspect water ingress.
a)Maybe through an air vent on deck, heavy rolling, water on deck, cracked or corroded vent pipe above deck level or faulty float valve.
b)Alternatively a hull crack in one of the tanks below the waterline which would cause that tank to keep overflow ing into the overflow tank.

4) If a) above was the case it would be fairly easy to effect temporary repairs.
If b) above was the case, the water would be displacing the oil from the leaking tank, so it would probably be best to allow the oil to continue to overflow until the other bunker tanks were 95% full or whatever was the maximum normal bunkering % on that ship, or until sea water was overflowing into the overflow tank. This would minimise the pollution risk. Then blank the overflow line from the leaking bunker tank to the overflow tank. First making sure that all the manhole doors and any sounding cocks to the tank were tight. Effectively the ship would be floating on the tank top/ inner bulkhead of the tank.
Once in port arrangements could be made for shore reception facilities for the oil and the overflow line "un blanked until as much oil as possible had been removed, before docking for repairs.
It would then be the drydock's responsibility to to catch the oil as it came out through the crack.

B)
1) The oiler found that one or more of the wing tanks had gone down in level.

2) As above all the tanks should have been sounded to determine where the oil was coming from.

3) Bunkering valves not properly closed and oil from one or more wing tanks gravitating down into a double bottom tank which then overflowed to the overflow tank.
4) Consume all the oil from the leaking tank first so that the valve can be opened up for overhaul. (unless it was only a sticking actuator, unless it was operator error).
B.P.

[JK]

In Scenerio 1 I am going to add the tanks should be sounded with water finding paste.

What happened was the next day the same watch goes on at Noon and the tank soundings are are all over the place from the day before. One wing tank is empty, let's say #2P.
CE tells the oiler he is full of it and to resound.
During the course of the watch, they go to transfer fuel and the fuel transfer pump starts acting up. When I go on watch, the set tank level is way down and the other engineer is scratching his head.
I shut all of the quick close valves to the wing tanks, then open up the FO transfer manifold, starting with #2P. Actually I ended up opening all of them to check the condition of the valves .
#2P wing tank valve has worn enough to lift up and jam crosswise on the seat. I rebuild the valve reassemble the manifold and open up the quick close valves then transfer fuel.
The FO transfer pump had been trying to draw from an empty tank.
The watch had 2 problems. Yes, the tanks had initially overflowed from the rolling, but everytime, they opened the transfer valves to pump, the wing tank was pumped out of as well, they redistributed that tanks fuel through all of the other tanks, plus probably recirculated back to that particular tank several times. This went on until the tank was empty and then the pump lost suction.

They should have sounded the tanks with water finding paste as soon as the ship rolling stopped.
The tank valves should have been shut, nevermind we had to then open up the pipe tunnel to get into it to open them back up. As soon as the transfer pump started acting up, they should have realized that there was an open valve to the empty tank.

It is only the fact the Chief never had the time and opportunity to completely bunker the ship to 95% on that day, that saved us from a nasty fuel spill.

[Pacific Barbarian]

Have to admit that sounding tanks in the middle of the night sure is a pain in the ass. On our vessels we have remote sounding system on a computer which really simplifies things, so problems can be picked up quite easily.

If you do not have this luxury, part of good watchkeeping is to physically going around sounding the tanks, pain in the ass but has to be done!

Remote tank indicator is luxury, but still needs to be maintained and kept in calibration, but sure as hell a lot easier than taking dips!!!

[JK]

The ship does have a remote tank sounding system. Tanks are ( or were, who knows now) physically sounded daily.