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Author Topic: Funnel Bases.  (Read 2650 times)

Bryan Young

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Funnel Bases.
« on: September 29, 2007, 07:12:29 PM »

A question for you Marine Engineers out there.
On many photos of very old ships the funnel appears to have a swollen base. There must be a reason for it. So what is it and what is it for?
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Colin Bishop

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Re: Funnel Bases.
« Reply #1 on: September 29, 2007, 08:46:27 PM »

I'd have thought that is was simply the uptakes from the boilers on each side if the stokehold being combined into a single vertical flue. Similar to warships where the funnels could frequentlt be seen trunked fore and aft.
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PSSHIPS

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Re: Funnel Bases.
« Reply #2 on: September 29, 2007, 08:58:04 PM »

There are varying reasons for different types of bases and flues, cooling etc and ducting etc, there is no set standard, it depends on power plant, then you may get a set standard, if ya know what I mean?
 I thought that Bryan may have been a bit better informed being a "skipper" as to why his ship was designed the way it was and Colin, there are not many ships still burning coal and the stoke hold as you put it went it's way a long time ago.  The funnel base in most cases was the funnel uptake, inside which the flues from one or more boilers and economisers were ducted before final ejection from the ship.
 I hope this helps, :)
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Ghost in the shell

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Re: Funnel Bases.
« Reply #3 on: September 29, 2007, 09:15:03 PM »

I'd have thaught that the flues from the boilers would form a "manifold" linking several boilers together deep down in the bowels of the ship, before going up to the funnel, therefore reducing the space they take up.  the rounded bases i think are probably for getting the galley and room ventilation housed from several areas of the ship merged into one uptake, as well as creating a seat for the funnel
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Bunkerbarge

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Re: Funnel Bases.
« Reply #4 on: September 29, 2007, 09:21:29 PM »

I would suggest that ventilation is more often than not the cause of what you are seeing.  Most uptakes go up the funnel and the casing passage (the vertical spave that goes up from the engine room into the funnel) usually carries ventilation supply and extract trunking and plenums.

Usually up the fiddly you also have tank vents, crankcase vents, steam relief valve outlets etc going up to the top of the funnel.

Bryan do you have a picture of what you are referring to?

Paul don't forget that a lot of old names on ships have long since outlived thier original purpose but the name remains.  Bunkers used to refer to coal recepticles but has since been continued into fuel oil tanks and a thunderbox referred to a toilet that discharged directly into the sea but some of us old timers still refer to modern vacuum toilets as such.

Ghostie, boilers are not linked together by thier exhausts, they, like engines and incinerators all have thier own seperate uptakes.
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PSSHIPS

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Re: Funnel Bases.
« Reply #5 on: September 29, 2007, 09:23:13 PM »

Mark, are you for real? In some cases maybe, but, take a look at some propper ships and their drawings. Don't forget you were the one that didn't know why water comes out of holes in a ship at the front aswell as at the back and in the middle, then almost everywhere else in the hull and sometimes even out of the superstructure. There are more things going on inside than meets the eye from the outside, remember Plymouth, what did you think all those pipes were for all over the place? Show? There are alot of systems on a ship that use common ducting etc, the funnel isn't normally the main one.
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Bryan Young

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Re: Funnel Bases.
« Reply #6 on: September 29, 2007, 09:47:50 PM »

I would suggest that ventilation is more often than not the cause of what you are seeing.  Most uptakes go up the funnel and the casing passage (the vertical spave that goes up from the engine room into the funnel) usually carries ventilation supply and extract trunking and plenums.

Usually up the fiddly you also have tank vents, crankcase vents, steam relief valve outlets etc going up to the top of the funnel.

Bryan do you have a picture of what you are referring to?

Paul don't forget that a lot of old names on ships have long since outlived thier original purpose but the name remains.  Bunkers used to refer to coal recepticles but has since been continued into fuel oil tanks and a thunderbox referred to a toilet that discharged directly into the sea but some of us old timers still refer to modern vacuum toilets as such.

Ghostie, boilers are not linked together by thier exhausts, they, like engines and incinerators all have thier own seperate uptakes.
You seem to be the sensible one to talk to.
As I was not even a glimmer in my grandfathers eye at the time I am totally at a loss about these funnel bases. Look at the rather nice pics of HMS "Majestic" posted recently and you will see them. Although I once sailed in a ship built in 1918 her funnel was just a straightforward pipe.
The ones I am asking about are, in the base area, much larger in diameter than the funnel. They did not have vents or any other orifices, just a massive base trunking blended into the funnel proper.
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Colin Bishop

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Re: Funnel Bases.
« Reply #7 on: September 29, 2007, 09:57:36 PM »

Paul, Bryan did specify that he was talking about older ships which is what my suggestion referred to. You should read before replying. Actually I was recalling my recent visit to HMS Warrior where the boiler flues do indeed combine in this way. You can look up from the stokehold and from the intermediate decks and see this. Bunkerbarge will know what I mean as he got married on the ship, although I suspect not in the stokehold which I imagine is reserved for divorce proceedings!

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Bob

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Re: Funnel Bases.
« Reply #8 on: September 29, 2007, 10:38:04 PM »

Swelling of funnel bases would, I suggest, come about because of a number of factors.   Situation of boilers IE two or more athwartships, size/type of boiler,breadth/ height, Scotch or Yarrow, multiple boiler rooms, space available to fit the boilers or combination of boilers, depth of hull in a long skinny vessel, and the need for a easy flow for the combustion gases. Support of long tall funnels, (furnace draught considerations) also needed a solution and a larger base would assist.   
From the skippers point of view, windage would also have to be taken into consideration.
Bob Ferguson.

PS Can't spell athwartships. Had 3 goes and still not sure
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DickyD

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Re: Funnel Bases.
« Reply #9 on: September 29, 2007, 10:40:21 PM »

Didn't miss much there Bob and your spelling is alright  O0
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RickF

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Re: Funnel Bases.
« Reply #10 on: September 30, 2007, 12:23:49 AM »

Bryan,

Going back to the days before even you or I were about - back in the 1850s  - the funnel base might have had several possible uses.The first that springs to mind would be to house the telescopic mechanism "Down funnel, up screw!". A quick look in Bourne's "Treatise on the Steam Engine" (1868) suggests that it could also have housed the superheater or the equivalent of a locomotive's steam collecting dome.

However, Victorian warships seem to have had this casing fitted with a sloping roof and a vent all around the top, so for want of any better information I think it later probably served as an air uptake/vent.

Rick
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Martin [Admin]

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Re: Funnel Bases.
« Reply #11 on: September 30, 2007, 12:37:12 AM »

Topic moderated and brought back on track.
 >:( NO ABUSE OF ANY KIND WILL BE TOLLERATED ON THIS FORUM! >:(


                                                       Lets stick to the acual subject shall we?
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Bunkerbarge

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Re: Funnel Bases.
« Reply #12 on: September 30, 2007, 12:51:14 AM »

You can't beat getting married on a warship to start things off on the right foot!!

Not having first hand experience I am going to have a stab at another suggestion.  In early steamship times the funnels always seemed to be a straight cylinder, which I would suggest was for no other reason than they were easier and therefore cheaper to make that way.  This type of structure on a ship is inherently not too stable and hens most early funnels has substantial shrouds fitted to stop the thing falling over.

What if someone actually decided to put a bit more design into the thing and said "'ang about, why do they have to be a tube, lets make them a more pleasing and structurally sound shape"  Hence the first steps towards this may be nothing more than an enhanced base to support the cylindrical section and offer a bit of support.

Might be a possibility.  I can't think of many other reasons for such an increase in diameter that does not have any inlets or outlets in it.
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Martin [Admin]

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Re: Funnel Bases.
« Reply #13 on: September 30, 2007, 01:13:06 AM »

.... as I ( and other I suspect) don't know what is actually being talked about here, has someone got an example to show us please?
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Bunkerbarge

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Re: Funnel Bases.
« Reply #14 on: September 30, 2007, 01:45:53 AM »

I take it thats why some of the early steam liners used cable stays on the funnels as well?

That's what a shroud is.
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RickF

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Re: Funnel Bases.
« Reply #15 on: September 30, 2007, 01:51:06 AM »

Here is a cross section of the forward funnel and boiler of HMS "Marathon", a 2nd Class Protected Cruiser of 1888. It illustrates what I said earlier about a sloping "roof" over the enlarged part of the funnel.

Rick
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Shipmate60

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Re: Funnel Bases.
« Reply #16 on: September 30, 2007, 07:12:34 PM »

Like This Prinz Eugen  one.

Bob
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Colin Bishop

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Re: Funnel Bases.
« Reply #17 on: September 30, 2007, 10:21:40 PM »

Did the rest of the ship ever get built? I remember making the funnel of a model first once to encourage me to finish the bit underneath!  ;)
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Bunkerbarge

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Re: Funnel Bases.
« Reply #18 on: September 30, 2007, 11:06:51 PM »

Now the slope at the front of that one is to allow the exhausts from the forward machinery spaces an easier path to the uptakes without having to take a 90 deg bend.
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Shipmate60

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Re: Funnel Bases.
« Reply #19 on: September 30, 2007, 11:07:42 PM »

Colin, she is comming along far more slowly than I ever thought.
German Heavy cruisers dont fly very well!!
When I was last at sea she fell off the shelf onto the worktop, the bits of superstructure carrying on to the floor.
Some of these styrene parts are over 20 yrs old and unpainted. UV has made the unpainted parts brittle, so lots of repairs to do.
My wife spent 4 hours picking up any bits off the garage floor that looked like they might belong to a model. My thanks to her.
So a bit longer than I thought, but comming along slowly.
New motors fitted and electrics by ACTion also semi-jury rigged, just lots of repairs to finish and paint.
She WILL be finished and sailing.

Bob
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Colin Bishop

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Re: Funnel Bases.
« Reply #20 on: September 30, 2007, 11:19:14 PM »

Look forward to it Bob. have you read the "autobiography" of Prinz Eugen? I forget who wrote it but it was a good read.

Colin
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Bryan Young

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Re: Funnel Bases.
« Reply #21 on: October 01, 2007, 06:39:14 PM »

There are varying reasons for different types of bases and flues, cooling etc and ducting etc, there is no set standard, it depends on power plant, then you may get a set standard, if ya know what I mean?
 I thought that Bryan may have been a bit better informed being a "skipper" as to why his ship was designed the way it was and Colin, there are not many ships still burning coal and the stoke hold as you put it went it's way a long time ago.  The funnel base in most cases was the funnel uptake, inside which the flues from one or more boilers and economisers were ducted before final ejection from the ship.
 I hope this helps, :)
Does'nt, but thanks for trying!
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Bryan Young

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Re: Funnel Bases.
« Reply #22 on: October 01, 2007, 06:41:30 PM »

I would suggest that ventilation is more often than not the cause of what you are seeing.  Most uptakes go up the funnel and the casing passage (the vertical spave that goes up from the engine room into the funnel) usually carries ventilation supply and extract trunking and plenums.

Usually up the fiddly you also have tank vents, crankcase vents, steam relief valve outlets etc going up to the top of the funnel.

Bryan do you have a picture of what you are referring to?

Paul don't forget that a lot of old names on ships have long since outlived thier original purpose but the name remains.  Bunkers used to refer to coal recepticles but has since been continued into fuel oil tanks and a thunderbox referred to a toilet that discharged directly into the sea but some of us old timers still refer to modern vacuum toilets as such.

Ghostie, boilers are not linked together by thier exhausts, they, like engines and incinerators all have thier own seperate uptakes.
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PSSHIPS

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Re: Funnel Bases.
« Reply #23 on: October 01, 2007, 09:51:46 PM »

Why, thankyou Bryan and Bunky, isn't it nice to have sensible replies to sensible postings, Bunky is correct as I tried and failed to explain the other night, boilers have their own uptakes, but, when they get to the funnel, they may be joined by several other boiler/ engine uptakes and all sorts of other systems that use the funnel casing as a common exhaust, the ventilation thing comes in where they combine ships machinery space vent exhaust to cool the uptakes before finally exhausting out of the ship via the funnel, on some ships, crank case vents from deisels etc normally come out below the top of the funnel or away from the funnel completely depending on design and purpose as build up of oil and soot deposits can be a fire danger.

 Now I hope that this helps?

 Best regards, Paul...
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