Heckler
Well-Known Member
Excellent description
Stu
Stu
What IS bunker oil?
- Thread starter Greenheart
- Start date
Heckler
Well-Known Member
cryan
Well-Known Member
Bunker Oil is any oil bunkered as fuel, Most large commercial ships use Heavy Fuel Oil, HFO. HFO is approximately 360 centistokes in viscosity @ 40 degrees centigrade (engine sump oil is normally 40 centistokes @40 deg for a comparison). It is a residual fuel very similar to bitumen at room temperature. It is heated with either steam coils or thermal heating oil coils to about 120 degrees centigrade to put through the injectors but it is stored at about 60 degrees centigrade. It is pumped to the settling tank from the bunker tanks. Here it is settled out to drain water off the bottom. It is then purified through a centrifuge and filters and transferred to the service tanks where it is brought to the operation temperature (120deg) in a device called a viscotherm which regulates the temperature. it is then pumped to the fuel rail via final filters and injected. Very few ships switch to diesel or marine gas oil before docking these days as the system tends to leak like crazy when you do and ships are rarely in port long enough to require it. They will switch if drydocking or putting in to port for a few days or more. It is usual to keep one generator set up on Marine Gas oil as an emergency back up as HFO is a nightmare in a blackout situation as it solidifies in the pipes if unheated. HFO is also very high in sulphur. however it is considerably cheaper than either marine diesel or marine gas oil which is of great importance when your burning 360 cubic metres of fuel per day. I have sailed on ships which may carry 15,000 cubic metres of HFO but only 10 cubic metres of Marine Gas Oil for a back up for emergency generators.
To answer the other question. Fuel tanks are cleaned now and then. Bunker tanks not so much but settling and service tanks are cleaned at each five year drydock.
To answer the other question. Fuel tanks are cleaned now and then. Bunker tanks not so much but settling and service tanks are cleaned at each five year drydock.
AngusMcDoon
Well-Known Member
daveyw
Well-Known Member
Cryan, your details are better than mine but then I've not been on a ship for 28 years! Our gennys were always on diesel, they were about 750kw to 950kw. Think we always changed to diesel during pilotage but then again it was cheaper in those days. The only ship I was on that didn't use HO was a methane carrier when we burnt the cargo in the boilers!
Heckler
Well-Known Member
John
All the crackers I worked with used heat
Stu
All the crackers I worked with used heat
Stu
cryan
Well-Known Member
The few times we ever had to switch to diesel the E/R was like a Gas Oil rain storm. Ships these days are on 12 hour turnarounds at best so switching over is an non required hassle. I've not seen HFO for a few years now as I finished up on offshore boats and then inshore tugs which all ran on MGO. I don't miss the HFO, it's nasty stuff.
AngusMcDoon
Well-Known Member
Maybe so, but still cracking is more than just heating and condensing; distillation does that. Cracking causes chemical changes...gloop in, petrol out.
Amulet
Well-Known Member
An admission of ignorance. One of the marinas I visit (Ramsgate ?) has a sign saying "No bunkering in the marina". Since I don't know what "bunkering" means, I live in anxiety that I might be doing it.
Presumably it has something to do with this thread.
Presumably it has something to do with this thread.
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prv
Well-Known Member
Bunkering just means refuelling. Whether you burn road tar, diesel, or petrol.
Some marinas worry about people topping up from jerrycans and spilling fuel everywhere.
Pete
Amulet
Well-Known Member
Tempted to say - why don't they just say "refuelling", but it would be a breach of nautical tradition to use plain language. Good heavens, people might start to think a sheet was a bit of cloth!
prv
Well-Known Member
Bilgediver
Well-Known Member
They do in the Royal Navy where they hook up at sea for a RAS and take fuel and other things. However traditions live on in the MN. It is surprising how many words used in these forums and elsewhere go back to 16th century sailing and beyond.
cryan
Well-Known Member
RAS stands for Replenishment At Sea not refuelling. I have never sailed in the Grey Funnel Line but I was previously employed in marine ops at Rosyth Royal Dockyard. When we used to fuel the warships before sea trials they used to pipe that Fuel Bunkering was in progress, however they used to call the barge the Fuel Barge where as in the the MN its always the Bunker Barge. When we received fuel from them before dry docking they piped for De-Fuelling Ops, not de-bunkering? The RN also call Diesel, DIESO which I never understood. In the MN its called Marine Diesel Oil colloquially MDO or Marine Gas Oil = MGO or just Diesel and Gas Oil.
AntarcticPilot
Well-Known Member
Yes. Not allowed in our marina, either, and the fuel berth (where it is allowed) has all the kit to cope with a spill. They are extremely careful about mopping up even a tiny spill. It's funny, really - the loation is a Victorian dock which over the years must have seen most kinds of fuel spilled in it. But it's regarded as a heritage site now, and the owners (Clydeport) are very keen on it being kept clean, to the extent that we don't pump oily bilge-water out.
Kukri
Well-Known Member
In the 1980s my then employers had a nice little 30,000 ton product tanker built at Tsuneishi which we owned jointly with a very charming bunch of Norwegians. She spent quite some time pottering up and down the South and East China Sea loading bunker fuel oil at Dalian, discharging it at Singapore, loading bunker fuel oil at Singapore and taking it to Dalian.
This made sense because in those days Chinese refineries were a bit basic; the stuff you got in Dalian was worth "re-cracking" in a modern refinery in Singapore and this and the export tax rebate (I never understood how that worked) paid for the freight.
We did get her clean again in the end.
This made sense because in those days Chinese refineries were a bit basic; the stuff you got in Dalian was worth "re-cracking" in a modern refinery in Singapore and this and the export tax rebate (I never understood how that worked) paid for the freight.
We did get her clean again in the end.
Greenheart
Well-Known Member
Was any part of her cargo usable as the vessel's fuel?
Kukri
Well-Known Member
All of it would have been, yes, but we were NOT THAT SORT OF SHIPOWNING COMPANY.
In fact I can bore for Britain on this subject as I had spent some time bringing another shipowner, who did help himself to the cargo, to justice.
A few years earlier, ships were being built with connections between the cargo and bunker tanks for use as required. My employers bought a nice 1975 Dutch built steam VLCC laid up in Greece and the first time I went on board in lay up the first sight that met my eye was the manifold with the bunker to cargo connection in place - my first instruction was "gas axe that!" as there was no way any owner could risk being seen with such equipment by the mid-80's.
I remember chatting to one of DK Ludwig's ULCC Masters who, in the Seventies, had found himself short of fuel for some reason and had asked his charterers, who were Exxon I think, if he could "help himself" to their cargo - their only question was "Did it burn OK?" Of course, having crude oil, with its low flash point, in an engine room is contrary to a raft of regulations and obviously very dangerous yet it was often done and maybe it is still done today. A number of tanker engine room fires and explosions are attributed, sotto voce, to this, but nothing has been proved.
There was a theory that diesel engines didn't like crude oil - this was blown to smithereens when someone in Brookes Bell pointed out that a pipeline had been built with diesel booster pumps which took their fuel from the line and they needed less maintenance than most!
Greenheart
Well-Known Member
Very interesting stuff. I suppose that however hellishly thirsty big crude-carriers are, they must potentially have the longest range of any non-nuclear vessels!
View attachment 31809
I wonder what her gallons-per-mile consumption was?
View attachment 31809
I wonder what her gallons-per-mile consumption was?
Kukri
Well-Known Member
I remember her well. About the same as a modern large containership, 270 tons/day, but she was a 15 knot steamer and they are 24.5 knot motorships.
A modern motor tanker is incredibly fuel efficient - the most fuel efficient means of transport known to man.
Actually almost all deepsea merchant ships are built to have a range on full tanks of 20,000 nautical miles, unlike the Royal Navy's toy boats which can barely waddle across the Atlantic at reduced speed before refuelling.