The Naked Scientists

The Naked Scientists Forum

Author Topic: Do ships use leaded fuel?  (Read 5692 times)

Offline KTell

  • First timers
  • *
  • Posts: 1
    • View Profile
Do ships use leaded fuel?
« on: 03/05/2009 21:30:27 »
Hi - I heared rumors claiming that the lead taken out of petrol for cars is put into fuel used in ships since there are no restrictions for lead in petrol on open sea. Any ideas (or references) if this is true?
Thanks,
KTell

[MOD EDIT - please format thread titles as questions, in line with our forum policy. Thank you.]
« Last Edit: 03/05/2009 23:36:17 by chris »


 

Offline graham.d

  • Neilep Level Member
  • ******
  • Posts: 2208
    • View Profile
Do ships use leaded fuel?
« Reply #1 on: 04/05/2009 00:21:58 »
I don't know for sure, but I would have thought it very unlikely. Ships tend to run with diesel engines and I did not think that there was much point in adding lead. There maybe some high performance (but smallish) motor boats running on leaded petrol, but this would not have a huge impact on the world.
 

lyner

  • Guest
Do ships use leaded fuel?
« Reply #2 on: 04/05/2009 01:30:43 »
There are no suppliers of leaded fuel for (small, of course) marine petrol engines. Afaik.
I don't think there are any large marine petrol engines. Diesel is best for constant load, continuous running.
 

Offline graham.d

  • Neilep Level Member
  • ******
  • Posts: 2208
    • View Profile
Do ships use leaded fuel?
« Reply #3 on: 04/05/2009 10:04:04 »
A friend of mine had a boat with two 7 litre Volvo petrol engines. He took it over to Holland once and it cost him more than it would have for him and his wife to fly there in a private aircraft. I prefer wind power personally. Older petrol engines can use an additive to the petrol like "valve guard" in place of leaded petrol.

There is likely to be legislation some time about two-stroke engines which are used a lot in small outboard motors. They put out a lot of hydrocarbons into the sea.
 

Offline Karen W.

  • Moderator
  • Naked Science Forum GOD!
  • *****
  • Posts: 31653
  • Thanked: 5 times
  • "come fly with me"
    • View Profile
Do ships use leaded fuel?
« Reply #4 on: 04/05/2009 10:36:20 »
My husband having served on the "U.S.S. SARATOGA" says that it is strickly diesel..on the big ships and Aircraft Carriers.
 

Offline AlphBravo

  • Full Member
  • ***
  • Posts: 65
    • View Profile
Do ships use leaded fuel?
« Reply #5 on: 04/05/2009 23:47:41 »
I thought ships use crude oil with a mixture of sand to power themselves across the seas?
Diesel surely for lesser vessels!
 

Offline Karen W.

  • Moderator
  • Naked Science Forum GOD!
  • *****
  • Posts: 31653
  • Thanked: 5 times
  • "come fly with me"
    • View Profile
Do ships use leaded fuel?
« Reply #6 on: 05/05/2009 00:40:55 »
Diesel is what  they use in boilers to make the steam..... Some ships, smaller ones that have diesel internal combustion engines, burn diesel.
 So your gonna burn crude oil and sand eh?
 How about vinegar and oil too ???
 

Offline Mazurka

  • Hero Member
  • *****
  • Posts: 510
    • View Profile
Do ships use leaded fuel?
« Reply #7 on: 05/05/2009 09:34:21 »
Ha!
I will put on my pedants cap on and contradict you all.
Ships use fuel oil (of which "diesel" is one of the 6 grades). In a nauticcal context it is commonly referred to as "bunker fuel".

Bigger ships use heavier fuel (as their bigger engines can cope with it)  Heavy fuel has more longer chain hydrocarbons. It is also cheaper as it has few uses that lighter grades.

A lot of waste oil from motor vehicle breaking and servicing gets used as bunker fuel by blending it with clean oil.

I would be suprised if sand were added to a fuel.  I have seen the damage that sillicate compounds (from siloxanes in soaps and shampoos) do to pistons, cylinders and plugs on landfill/ sewage gas powered generators; and it is not pretty!
 


lyner

  • Guest
Do ships use leaded fuel?
« Reply #9 on: 05/05/2009 22:53:16 »
Diesel is what  they use in boilers to make the steam..... Some ships, smaller ones that have diesel internal combustion engines, burn diesel.
 So your gonna burn crude oil and sand eh?
 How about vinegar and oil too ???

SteamShips use very heavy low-grade fuel in boilers and have steam engines. Motorvessels use lighter fuel in internal combustion engines (diesel cycle). With big engines, that fuel can be very heavy and sludgy. There used to be a limit on the sizes of IC engines but, these days, they seem to be as big as the biggest steam engines.
 

Offline Mazurka

  • Hero Member
  • *****
  • Posts: 510
    • View Profile
Do ships use leaded fuel?
« Reply #10 on: 06/05/2009 17:57:21 »
Mazurka,
Surely you know that not all diesels run on fuel oil?
http://cgi.ebay.co.uk/PAW-Special-2-49cc-Vintage-model-diesel-engine_W0QQitemZ260404309125QQcmdZViewItemQQptZUK_ToysGames_RadioControlled_JN?hash=item260404309125&_trksid=p3286.c0.m14&_trkparms=66%3A5%7C65%3A10%7C39%3A2%7C240%3A1318%7C301%3A1%7C293%3A1%7C294%3A25

Absolutely - it is the difference between engines using the Diesel (compression igntion) (rather than Otto(spark ignition)) cycle and engines using diesel fuel.

In the dim and distant past, (confusingly) I worked with spark ignition diesel fueled generators. 
 

Offline Edster

  • Full Member
  • ***
  • Posts: 57
  • Thanked: 1 times
    • View Profile
Do ships use leaded fuel?
« Reply #11 on: 06/05/2009 18:21:15 »
Yep I`ve heard about  things like that too: Spark assisted Diesel


If you discard smaller vessels, then ships such as ferries, tankers and liners that don`t use external combustion (steam)
are compression ignition engines. As has been said above they operate using residual oils, which are heated to make them fluid enough to spray from the injector nozzles.

The compression ratio is high  so that the compressed inlet air is at a temperature great enough to ignite the fuel when it is sprayed into it at , or near the top of the compression stroke



Petrol is a lower temperature fraction, and more volatile and is usually only used in spark ignition engines.

 The fuel is already in the cylinder during the compression stroke, mixed with air. If the compression ratio is too high for the fuel grade then it will self ignite before the top of the stroke, as in the compression ignition engine above.
This is pre-detonation or knocking: the dreaded "pinking" if it is just starting to occur.

The effects of this are damaging to the engine, from bearings to pistons and valves from shock and thermal effects.

Leaded petrol has a chemical cocktail including tetraethyl lead to suppress this.

 As you can see this is irrelevant in a compression ignition engine.

Leaded petrol will remain in all piston aviation fuel because of the secondary role of the lead additive in lubricating valve seats, and the improvements in reliability this brings. And no good equivalent has yet been found.


Unleaded petrol still has a very nasty additive package to do the same job, and the deliberate financial decision by the oil companies to make a reduction in the equivalent octane number means lower c/r`s have to be used. So not really very green after all.

« Last Edit: 06/05/2009 18:47:11 by Edster »
 

The Naked Scientists Forum

Do ships use leaded fuel?
« Reply #11 on: 06/05/2009 18:21:15 »

 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums