Ventilation

Bob Read

Active Member
The ventilation system on the Olympic class ships is one in which I've had particular interest. This particular thread may represent a rivet too small for the rivet heads to count but here it is:

On both Olympic and Titanic there is a 20 inch cowl sirocco fan which is located on the raised roof over the First class lounge on the port side
of the boat deck at frame 6A. It provides exhaust for the first class Dining Saloon below it on D deck. One of the cardinal rules for fan ducting is that the ducting travels between deck frames which correspond to hull frame spacing for the most part. This duct from this particular fan however is centered directly over frame 6A at the Boat Deck level. I have looked at the Boat Deck Iron plan and the promenade deck plan and the C deck plan and none of them show any unusual deck framing outboard of the First class lounge. My question is how did they
accommodate the framing directly in the path of the duct between the Promenade deck A and the fan on the raised roof? I have been unable to find any Olympic/Titanic photos showing this small indented area between the windows of the lounge on promenade deck A. I am wondering if the fan duct bifurcated at the boat deck level and two smaller cross section ducts ran down either side of this indentation to avoid deck frame 6A on both the Boat deck and the promenade deck. Below that they may have needed to rejoin but I'm really just interested in what the story was at the promenade deck level. I'm going to incluce a link to a drawing of the starboard side which would only apply to Titanic but the principle is the same. If anyone has a photo which may show this indented area clearly on Olympic on the port side I'd really like to see it. There a lot of Olympic photos out there but I don't think I've ever seen this area covered clearly. Thoughts or evidence anyone?
http://webpages.charter.net/bpread/photos/duct.JPG
 
No evidence and few thoughts. Without more information on this "indentation" I'm not quite sure what the difficulty is.

"One of the cardinal rules for fan ducting is that the ducting travels between deck frames which correspond to hull frame spacing for the most part."

Possibly superstructure framing did not correspond in this case. Outside of the ship girder proper I would think there would be some leeway for the designers.

Why bifurcate when you can throw the duct either forward or aft of the frame? In the absence of GA detail showing some countervailing impedance I would have thought that would have been the chosen solution.

Noel
 
Bob,I worked in h&w's vent squad as a plater for a while in the 50's & 60's & the squad was given "carte blanche" as to where the trunking went.The area had to be maintained,the shape didn't matter.For example,a 10"x10" could be 5"x20".or vice versa.The ducting took second fiddle to all else.The structure of the boat could not be interfered with.I trust this will be of benefit to you.
regards.
dw.
 

Bob Read

Active Member
Guys:

Thanks for the input.
Noel: I suggested bifurcation because in the given space, I'm not sure one could make a duct with the same cross sectional area on either side of the frame in that space. I have the Boat Deck Iron plan and there does not appear to have been any alteration in the normal framing outboard of the raised roof which is where this duct had to travel.

David:
Your answer tells me a lot. I wondered whether special framing would have been done to accommodate a duct like this. It sounds like you are saying that the strength elements were not compromised or even altered for the ducting.

One can imagine quite a few ways the ducting could have been routed. Now if someone only had a photo which showed this port area on the promenade deck of Olympic. I only bring this up because this is an exposed area of the promenade which for modelling purposes would need some solution.

Regards
Bob Read
 
Bob,

I see what you mean! This photo:

95904.jpg


Shows the ventilation duct on the Olympic, and it ran directly down from the vent on the boat deck above. You can trace it on some Olympic 1st class accommodation plans on B and C deck in the wardrobe rooms. I forgot where it went.

I don't know enough to know whether such an arrangement would have been on Titanic, but I see what you mean about those ducts in between the bay windows of the Lounge. This area is not often seen in photos, so the ducting usually gets left out of the models, however it obviously ran down from the boat deck, and went somewhre. I wonder whether or not they managed to hide it behind the Lounge paneling, or whether it ran against the deck house like in the photo I posted.

Regards,

Daniel.
 
I have a port-side boat deck photo of the Olympic under construction, showing this general area. Let me look for it in the next day or so and see what it shows...
 

Bob Read

Active Member
Daniel:

The photo you posted is not the duct in question.
That particular duct is found between frames 8F and 9F from the sirocco above on the boat deck on the starboard side between the forward bulkhead of the lounge and the aft bulkhead of the Gymnasium. The one similarity this one has to the duct I am referring to is that both are from 20 in. sirocco fans. I have combed through all of the port side Olympic images I have and none shows the area clearly enough to look at this duct.
The only hope I have is that at some point a photo was taken during Olympic's career showing this area on the port side. I haven't seen one though. But who knows, every once in a while a new Olympic photo shows up. There are none from Titanic and Britannic had a different arrangement. I'd like to add this to the target list of the upcoming Cameron dive but it probably wouldn't make the cut.

Regards,
Bob Read
 
Bob,

The fan in question was imaged during the NOAA 2004 expedition. Unfortunately, you are not going to see much underneath it, as the decks have collapsed upon one another. Looking at the fan atop the roof, there's no clue as to the ducting underneath.

The NOAA imagery is fairly comprehensive. The fan is shown from both sides and the Davidson & Co. Sirocco fan plaque is only partially obscured by rusticle growth (the same plaque on the centreline fan housing is not obscured in the least). You will want to look for those images when they become public, hopefully this year.

Please see my comment about dive targets on the upcoming expedition in the other thread.

Parks
 

Bob Read

Active Member
Parks:
Actually I have no questions about the fan. There are numerous photos of the 20 in. cowled siroccos on both Titanic and Olympic. It was how they handled the routing of the ducting when the ducting was centered directly over a deck frame rather than being over an interframe space
that made me curious. So I guess we can rule out Titanic wreck imagery as a possible source for information. Maybe an old Olympic photo will pop up in the future.

Regards,
Bob Read
 
Bob,

I'm aware of the fact the duct I posted is not the one in question. I posted it, as it is the only photo that I'm aware of, of a duct along a deck house, below a fan.

Have you got Peter Davis-Garner's modeling book? I was very impressed with the amount of detail he went into with his drawings. According to his drawings, two such ducts would have been seen in between the Lounge bay windows (that is one on each side), and another one along the fore outboard wall of the Reading and Writing Room (the latter not being on Olympic, and there is a Fr. Browne photo that shows this area from 1911 -- no ducting).

The fan is shown as sitting on the frame in question on the Lounge roof, and I assume the duct would have split to go on either side of the frame, but whenever not intefering with the framing, would be one solid duct. Unless the frames in this area were cut away, but is there any evidence on the iron plans to suggest that there was strengthening in this area due to sections of the frame missing to accommodate the ducts?

Daniel.
 
Daniel,

I think that David Wilson's rule of thumb above should not be forgotten...the frames were rarely interrupted and probably never for ventilaton ducting. As you've probably seen in the Olympic vent plans, the ducting takes on all kinds of interesting shapes in order to manoeuvre around the structure. The only instance where I have personally seen deckhouse frames interrupted for a feature was the Marconi skylight. At that, there were longitudinal stiffeners installed to help compensate for the loss of rigidity.

Bob, I recommend that you not dismiss the wreck images so readily, even if they show only what is visible above the deck. There are plenty of clues for what you are seeking. First off, the fan sits on a reinforced pad, as all the fans do. This is not a surprise. What this does, though, is make it difficult to see exactly how the fan straddles the frame underneath. But we'll come back to that in a minute.

This particular fan housing has corroded away on the outboard side, allowing one to see directly into the fan plenum. Looking at the interior configuration of the fan housing, I could see where the air would exhaust downward out the forward half of the housing assembly.

There's a corrosion hole in the deck outboard of this fan. The corrosion hole exposes a few frames. If memory serves correct, I believe that I noticed one of the frames lining up with the midline of the reinforced pan upon which the fan in question sits. If that's true (I would need access to the images again to verify), then I would say that the ducting underneath the fan is forward of the frame and therefore not bifurcated.

Parks
 

Bob Read

Active Member
Parks:
I'm not dismissing any wreck image evidence. What one has to concentrate on is the ducting of the fan on the outboard of the fan. The ducting
on Titanic first went through the roof of the lounge. It was then exposed for a short distance until it reached the boat deck proper. From plans of all the decks in question this "indentation" between the lounge windows is centered on frame 6A.
The difference between Olympic and Titanic is that the raised roof over this "indentation" was extended outboard so that the roofline was straight and did not follow the bulkheads of the lounge in this area. Also on Titanic, there was an additional sirocco in this same location on the starboard side. The Olympic boat deck iron plan shows no alteration of the frame makeup outboard of this area. Therefore the duct travelled downward from the level of the fan to the boat deck proper where it would encounter this frame 6A outboard of this "indentation". Something had to happen when this frame was reached. Either the duct had to go around the frame either on one side or the other, or it had to bifurcate, or possibly the frame
was surrounded by the duct. If the wreck images clearly show what is going on then I'd like to see it.
However, shifting this fan forward or aft would have placed the duct right down on top of the angled bulkheads of this "indentation".
I believe that what you are calling a "corrosion hole" is actually where the duct passes through Titanic's lounge roof extension. No such opening would be found on Olympic because the
lounge roof was not extended outboard like Titanic but rather followed the line of the lounge bulkheads which formed the "indentation".
Regards,
Bob Read
 
Bob,

The corrosion hole is large and very irregular. It's also some distance from the fan itself. It might have started around a pass-through, but has since grown. This hole does not show up in the earlier ANGUS imagery, to my knowledge. I would have to be able to directly compare the earlier and later images to be sure. The hole also exposes the interior of the R&WR...one of the lunette window frames can be seen poking out of the debris inside (the frame is obviously no longer mounted in the wall).

Parks
 

Bob Read

Active Member
Parks:
Now I'm really confused. I'm wondering if we are talking about the same fan. Are you possibly talking about the fan that ducts just forward of the Reading and writing room on the
port side? When you talked about the window frame from the Reading and Writing Room it threw me because that is well forward of the fan I'm talking about. Below is a link to a reference drawing which shows the fan in question. It is numbered #38. Also shown in red on the drawing is frame 6A. From what you are saying I'm wondering if you are talking about #30 also shown in this drawing. I'll stop here because if we aren't talking about the same fan then we first have to get the same frame of reference.
http://webpages.charter.net/bpread/photos/ventquest.JPG

Regards,
Bob Read
 
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