Now a question about funnel caps....

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chugwater shale
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Now a question about funnel caps....

Postby chugwater shale » Wed Jan 09, 2013 3:02 am

Hi all, and thank you for your answers about armor belt construction, by the way. At any rate, could anybody tell me the purpose behind capping a ship's funnel? It seems that the Germans modified many of their ships by adding caps to the funnel and I was wondering what specific benefit they gained from this.

As you may suspect I have neither a naval nor architecture background, but I am an industrial hygienist and do some idustrial ventilation design. Most frequently we put caps on vent stacks to keep rain out without slowing airflow and making a blower work harder, could that be the reason caps were added to S&G among other ships? Or did it have something to do with draw from the boilers and improving combustion?

Thank you

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RNfanDan
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Re: Now a question about funnel caps....

Postby RNfanDan » Wed Jan 09, 2013 11:32 am

Caps (not to be confused with "clinker screens" redirected the flow of funnel gases). Caps were not always necessary, and in some cases, not effective enough.

Have a look at the British Revenge class (or "R" class, as often described) battleships. Not all were capped throughout their service careers, and differences existed between the five ships' bridge structures. Note also, that various ships with two or more funnels would frequently have only their forward funnels capped, while their aft ones were not.

Caps were a "cheap" fix, as opposed to raising the entire funnel; caps could also be more easily "adjusted" than having to raise or lower a complete funnel, but it depended mainly upon the extent of the problem. An example of this can be found in photographs of Gneisenau, during the ship's early years (its first cap looked hideous, IMO :kaput: ). In other ships, perhaps most notably the British "County class" heavy cruisers, original heights were almost immediately raised for all three funnels, with those of the RAN higher, still. Capping would not have been as effective.

Dan
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chugwater shale
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Re: Now a question about funnel caps....

Postby chugwater shale » Wed Jan 09, 2013 5:25 pm

Ahh, thanks for that. Of course, that was one of the possibilities I was thinking about, but didn't include in my post! C'est la vie.

On a personal level, it has always irked me slightly than many books see fit to mention funnel caps being fitted--but never go into why--or how successful they were.

And in any event, thank you for your reply!

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RF
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Re: Now a question about funnel caps....

Postby RF » Sun May 12, 2013 4:47 pm

RNfanDan wrote:Caps were a "cheap" fix, as opposed to raising the entire funnel; caps could also be more easily "adjusted" than having to raise or lower a complete funnel,


Presumably the IJN practice of sloped funnels was for the same reason?
''Give me a Ping and one Ping only'' - Sean Connery.

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tommy303
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Re: Now a question about funnel caps....

Postby tommy303 » Sun May 12, 2013 6:12 pm

Presumably the IJN practice of sloped funnels was for the same reason?


Pretty much, in that the sloping of the entire funnel aft, as in the case of the Yamatos and a number of cruiser classes, directed (as opposed to deflected) flue gases away from bridge structures; I suspect the rather flowing designs of the funnels on these 1930s/early 40s warships also appealed to the Japanese sense of aesthetics.

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BobDonnald
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Re: Now a question about funnel caps....

Postby BobDonnald » Sat Jun 22, 2013 5:38 am

Did any of the WW1dreadnaught coal burners have capped funnels?

Bob

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RF
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Re: Now a question about funnel caps....

Postby RF » Sun Jun 23, 2013 5:58 pm

Interesting question. Of all the pictures I have seen of the High Sers Fleet, right up to 1919, none of the deadnoughts had funnel caps.
''Give me a Ping and one Ping only'' - Sean Connery.


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