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[tubby tomo]

i just typed ships engines into PC and saw the monster of all engines the biggest diesel in the world well worth a look

[HS93 (RIP)]

this one, yep a monster I  like the way when fitted to tankers they have there own refinery to convert the crude to fuel.

Peter


http://people.bath.ac.uk/ccsshb/12cyl/

[Ghost in the shell]

at 2300 tons, yes it is a tad large, yet turns at less than 200 rpm,

[boatmadman]

Wow! That is a BEAST!

Peter, I am not sure where you got the onboard refinery info from, but in my day anyway, marine diesels ran on heavy fuel oil most of the time, and changed over to diesel oil for manouvering. The type of engine - diesel engine refers in this case to the combustion cycle in use, ie, compression ignition.

The motor ships I worked on were about 36" bore by 40" stroke - a baby! (only about 8000 bhp)

The most interesting was a 6 cylinder opposed piston Burmeister and Wain - watching those top pistons going up and down at 120rpm was an impressive sight to a young engineer!

Ian

[DavieTait]

The "refinery" isn't its a large scale heater as heavy bunker oil need to be heated up to 120-180'C before going to the engine to be burned. Its not great for an engine to run on as heavy bunker oil is far less refined than diesel and has a lot more sulphur in it meaning the injectors need cleaning out on a regular basis compared to marine grade diesel

[Ghost in the shell]

basically marine fuel oil is the crap at the bottom of the column then?

[boatmadman]

Ghost, its a poorer grade oil yes.

Davie is right about heating the oil, if it is allowed to get too cool it goes like treacle! I remember in the Baltic in winter a bucket of fuel oil had been left out - careless! -  and it was so thick I stood on it and only left a slight footprint on the surface of the oil!

On the motor tankers I was on we changed to diesel oil for manouvering to avoid the risk of fuel oil cooling in the fuel oil systems - it would have been a nightmare to get a system full of cold heavy oil flowing again.

Ian

[Bunkerbarge]

That only seems like a lot of power of course because it is in a single engine but there are many ships around with higher powered multi-engined installations.

The QE2 for example has a total engine power of about 130,000 hp but that is split into 9 seperate and independant engines.

The biggest single engine I have sailed with was by the same manufacturer and was a 10 RND90.

That was a 10 cylinder 900mm bore engine.  They have upped the cylinder size now to 960mm.

As for fuel don't be fooled into thinking that the fact that it is a residual fuel means it is a poor quality.  Residual fuels actually have a higher calorific value than fractions from higher up the column which is one of the problems that used to be encountered when engines changed over from heavy to diesel in port.  You actually get less power out of it for a given rpm.

Strangely enough the industry has gone away from that now for a number of years and heavy fuels are used all the time but new legislation being considered around the world may force ships to use diesel in port again for the purposes of emmission control.

[anmo]

Very interesting.

Any idea what temperature residual fuels have to be heated to before they can be used in engines like these? I remember when the Napoli went aground off the Devon coast, the salvagers had to spend quite some time heating the fuel that remained on board, before it could be pumped into lighters.

[Bunkerbarge]

To be able to pump the stuff it has to be up to somewhere in the region of 40-45 deg C but to burn it in the engines and be at the required viscosity it has to be at round about 140-145 deg C.

Obviously a lot of concerns regarding the fuel systems from a safety point of view as regards fire and personal contact.  It is difficult to deal with a leak when you can't get near the stuff and you are faced with an ever increasing risk of it bursting into flames.

[Colin H]

Fancy trying to de-coke that beast the spanners alone must be a nightmare.

Colin H.

[a3nige]

Surprisingly, they are very easy to work on. We used to hang our cylinder head 'spanner' (air operated) on the crane counterbalanced with a bucket of concrete, get the crane in the right position & keep moving it round to the next nut to be tightened or loosened.
When we had been together a few months the 5 engineers (and sometimes the lecky) could change a cylinder head gasket on a Sulzer 6RND76 in less than an hour because we all knew what the other was doing. We could change an injector (3ft high) in about 5 Min's. Big pieces for little hands we used to say. I will have to get my photos scanned and I will post a few.
Nige

[boatmadman]

agree with you there Nige, the bigger they are the easier to work on.

one comical job I often had to do was adjust/tighten the exhaust valve tappet whilst the engine was running - usually at about 50 or so revs!

Used to get into a dance with the sledge hammer, timing the swing to the motion of the tappet, with my mate holding the spanner using a long length of rope - he didnt trust me with the sledge!

Cant remember for sure now, but I think the spanner sizes were about 150 mm.

Ian

[Bunkerbarge]

Nowadays cylinder heads are tightened down hydraulically and all at the same time so it couldn't be any easier.  It takes all the fun out of swinging a large sledge hammer though!  That was usually why the third engineers were built like brick toilets as they were the ones on the end of the hammer while the cowering little Fifth Engineer held the spanner on the nut.

In my experience the bigger the engine the easier it is to work on, especially Sulzers.  The RND 90's had a ladder inside the crankcase so that you could climb up to the piston stuffing box and crosshead slide assembly and everything inside was tightened hydraulically.  The main bearing caps were held by hydraulic tie rods and you could have the top shell out in half an hour.

[a3nige]

I remember the tappets on the Burmeister & Wain engines we had. we used to buy grinding paste by the box! I used to sit on a bosun's chair hung off the crane to go down the cylinder liner to measure the wear, 5mm I think was the limit, then it was changed and re chromed. We used a crowbar to break the old piston rings off the piston, the edges were so sharp they would take your fingers off if you touched them.
Great days, Chief Eng would come and say when we got into port " Number 2 head gasket, job and knock, we were up the road in less than 2 hours!
My favourite engine was the Sulzer. CP prop, UMS engine room, perfect.

Nige

[boatmadman]

Hydraulics? LUXURY! 

On the opposed piston B&W I was on, the 'sledge' for removing the top piston bolts was a lump of steel, about 12" diameter, maybe 36" long with 2 rings welded to it. This was slung from the crane, and with help of a rope fastened to another ring on the end, pulled away from the spanner and allowed to swing across the engine room and onto the spanner! health and safety? LOL!

I was the cowering J.E. standing on top of the piston guiding the 'sledge' onto the spanner! 

[sheerline]

On the question of fuel oil and its propensity to thicken and even solidify at lower temperatures, it would seem logical to conclude that should one of these vessels sink in deep water, the low temeratures found at great depths would solidify the stuff sufficiently to prevent it leaking out of the bunkers. Yes/No?

[Jonty]

  It's not just marine oil that gets sticky when cold. First time I went to India was by bus. It was so cold in eastern Turkey that in the mornings the truck drivers would light a fire of diesel under the engine sump and under the fuel tank just to get things going.

[Bunkerbarge]

On the question of fuel oil and its propensity to thicken and even solidify at lower temperatures, it would seem logical to conclude that should one of these vessels sink in deep water, the low temeratures found at great depths would solidify the stuff sufficiently to prevent it leaking out of the bunkers. Yes/No?

I'm afraid not.  At cold temperatures above freezing the fuel will be of a treacle like consistency, which will still flow, allbeit very slowly, and it will still float to the surface eventually. 

The only time I have ever seen it solid was taking bunkers in Montreal at -32 deg C.  Most things were solid at that point, including me!!

[john strapp]

Hi Boatmadman -  Used to think it was hairy just to watch the top pistons on an opposed piston Doxford going up and down, with the cooling water hose pipes flexing several times a minute over along voyage.

[Bluebird v2]

Aye there Jocky  :) or Mr Strapp - dont you mean the Doxford Flying Bedsteads?  Hairy things as you say, had six months with one of those engines and hated every nut n bolt of it - MV City of Columbo - ah how much bilge oil are we going to pump overboard from this thread - because Ive already got me Sou'wester on for all the broken water cooling pipes.

aye
John

[penfold]

this is a cracking thread to read,i love a good bit of technical talk!!!!!
  i am a bmw technician by trade( dont take the @*^" ) modern oil engines have very high feul pressures (300-1500 bar)for ncleaner burning, what sort of pressure do these engines have, and what sort of pumps, i am aware of some cat or cummins engines having  a pushrod operated injector (older engines, as most modern are solenoid operated) how do the injecters operate?
 i love the idea of swinging a hammer on rope! my foreman would love that.
 my late granadad served at scapa flow during the war fitting out rn ships i could sit for hours listening too his storys
  i know its a bit of track, but in this playstation world we live in its good to read of skilled workers,something this country has lost sight of!!! sorry i will get of my soap box
  keep the storys and facts coming,
   penfold

[boatmadman]

That particular engine had a habit of rupturing fuel lines between the pump and injector.
The alarm system was the boiler man - if there was a problem he would hit the plates with a hammer - the bigger the problem the faster he would hammer! One time it sounded like machine gun fire, I legged it up to the tops. saw oil spraying everywhere, lifted the fuel pump, looked over the handrails to find 4e only to see him protecting the girlie calendar from flying oil! 

[Bunkerbarge]

Well Bluebird, Doxfords, now we're talking about an engine!

After a few years on Sulzers and a few Crossley Pielsticks I found myself one day on the City of Opporto, fitted out with one of the last five production Doxfords.  The subsequent Seahorse experiments signified the final demise of the company as they strove ever harder with ancient technology to compete with the Sulzers and the Wartsila's of the world.

The City of Opporto was fitted with a three cylinder "Medium Speed" Doxford, which scared the living daylights out of me the first time I saw it.  The biggest problem was that when the rings on the top pistons started to wear, the engine lost compression and became unreliable to start.  On manoeuvring I would stand by the tops with a bucket of lube oil and the second the engine stopped I would pour a splash of oil onto the top piston to seal it ready for it's next start.  When it did I dissappeared in a cloud of oil vapour!!  By the end of stand by I was covered with oil.

I remember one occasion when we were going into the first lock of the Manchester Ship Canal at about 2.00 am.  The captain had been warned that the engine wasn't the most reliable at starting so give himself a bit of space.  I had handed the bucket to the greaser and gone out on deck for a smoke as we entered the lock.  We must have been doing about 4-5 knots as the stern passed the gates and I distinctly remember thinking "That's a bit fast, I hope she starts OK". 

I heard the chuff, chuff, chuff, chuff as it blew over from outside then, nothing!   Again chuff, chuff, chuff, chuff, not a peep. By this time I was taking the steps two at a time until I reached the tops and spotted the bucket on the top platform.  I grabbed it, threw the contents liberally at the top pistons before the third start kicked in, chuff, chuff, chuff, bang, chuff, bang, chuff, bang, bang, bang.  And the thing finally burst into life.  Full astern for what seemed like an impossible amount of time until the Old Man finally backed off and eventually stopped.

From conversation with the Third Mate the next day apparently the Old Man was white as a sheet for the rest of the morning and didn't speak a word to a soul.  It would seem we managed to stop only a matter of a couple of feet from the front gate!!

The greaser had, of course, decided that it was time to fill his bucket so was waiting for his can to fill up from the main tank!

I only did a few months on that ship but I learned a lot about Doxfords and I consider it a great priveledge to say that I sailed with not only one of the last, but also the fastest production Doxfords ever fitted to a ship.  When it started that is!!!

[boatmadman]

Well, Penfold,

If my memory serves me well - and it may not - I seem to remember injector pressures of 5000psi, these were old engines though!

The injectors lifted on fuel pressure from the pump. The pumps were usually cam operated.

One job I was on, we ran 3 cylinders on cenrifuged fuel, and 3 cylinders on homogenised fuel and we were monitoring liner wear using a radioactive source. It was my job to move the source from one cylinder to the next each week!

The experiment never did last, the homogeniser kept blowing apart!