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[sparkey]

Why did the Titanic have the arrangement of 3 props 2x 3blade on the outside and 1x 4blade in the middle, just that I saw a picture of her in dry dock and wondered is this common on large ships of the time,Ray. 

[roycv]

Hello I do not know specifically about Titanic as she had a relatively short life.

But Liners of that size and later larger ships could set up resonant frquencies at cruising speed and these would annoy the passengers and it was not uncommon for propellers to be changed to avoid this problem.
I can't remember detail but I recall at least one transatlantic Liner being in dry dock and having the props changed I think from 3 to 4 blades because of unwanted vibration.
We have a few experts on this subject on this forum who I am sure can be more specific.
regards Roy

[TheLongBuild]

Why did the Titanic have the arrangement of 3 props 2x 3blade on the outside and 1x 4blade in the middle, just that I saw a picture of her in dry dock and wondered is this common on large ships of the time,Ray.

Some debate as to was the Titanic a 3 - 4 - 3 , or a 3-3-3 bladed configuration.

http://www.encyclopedia-titanica.org/mystery-titanic-central-propeller.html

Also the picture of the props most commonly seen is that of the Olympics, Not the Titanics.

[sparkey]

Thanks Roy, you know when you look at something and think I wonder why they did that, and it sticks in your head until you find out,Ray. 

[sparkey]

The photo showing the 4 blade centre prop says it is the Titanic but I don't have proof, could be the Olympic which did have this arrangement,Ray.

[TheLongBuild]

The photo showing the 4 blade centre prop says it is the Titanic but I don't have proof, could be the Olympic which did have this arrangement,Ray.

From what I have read there are in fact no Photographs of the Titanic's props other than one at the wreck site , all the pictures are of the Olympic and over the years miss credited.

Reading the shipyard notes I doubt they would have got it wrong ?.

[Colin Bishop]

Titanic had reciprocating engines on the wing shafts and a turbine on the centre one. I imagine that the characteristics would have been very different, hence a different prop setup. I think the turbine would have been direct drive which would account for the smaller diameter than the wings props as the turbine would have had a higher RPM.

Lots of stuff on the web if you Google it.

Colin

[sparkey]

Thanks for the info. Colin,Ray

[radiojoe]

I'm with you Ray, this photo says it is Titanic, the centre one was driven by a low pressure turbine that was also non reversing, and was used when the outer two props had reached cruising speed.

[roycv]

Hi from the link Longbuild put up the turbine is a low pressure one powered by the exhaust steam from the outboard engines.
regards Roy

[TheLongBuild]

I'm with you Ray, this photo says it is Titanic, the centre one was driven by a low pressure turbine that was also non reversing, and was used when the outer two props had reached cruising speed.

problem is that mist of the pictures with Titanic on are intact the Olympic

[TheLongBuild]

problem is that mist of the pictures with Titanic on are intact the Olympic

Umm Never Type on a mobile !!   

As I was trying to say, as the Olympic was the first I would imagine that the pictures were of that Vessel, as the Titanic was only really famous, after it Sank, The O being the first of that line. Definitely a Mystery , only solved if the explore the props a bit more.

[Colin Bishop]

Olympic and Titanic were effectively sister ships so the machinery installations, including the props, would have been identical. No reason for them to be otherwise.

Colin

[TheLongBuild]

I'm with you Ray, this photo says it is Titanic, the centre one was driven by a low pressure turbine that was also non reversing, and was used when the outer two props had reached cruising speed.

Unfortunately from those photos it is hard to say , as Colin says they were almost Identical, if you have a side on bow shot you could tell which one it was as some of the platting is laid different.

My personal believe is that picture is of the Olympic.

[TheLongBuild]

Olympic and Titanic were effectively sister ships so the machinery installations, including the props, would have been identical. No reason for them to be otherwise.

Colin

Normally I would agree, However it does appear that the Builders / Owners were experimenting with the props & pitch, if the picture below is to believed . Which shows a 3 - 3 - 3, while the Olympic showed a 3 - 4 - 3  Could have been a typo ., could have been altered but then to what gain.

Also the document shows that Olympic for a period also had a 3-3-3 arrangement.

[Colin Bishop]

Well, it is certainly possible Larry although accepted wisdom appears to be that the centre prop on Titanic was a four blader. I do have a photo in one of my books which purports to be the Titanic showing a four bladed prop but it is suspiciously similar to another titled as Olympic showing the same area and exact pattern of portholes and waste discharges. But the ships were built from the same plans and there was very little difference between them apart from the plated in forward part of Titanic's promenade deck. I think there were also some differences in the porthole layout just below the foc'sle but even this is confusing as it was not uncommon for negatives to be printed the wrong way round to you cannot be 100% certain which side you are looking at!

Certainly when in service, many if not all of the big liners had various different props fitted as the vibration at high speed could be severe and very difficult to cure. Queen Mary had to have the whole of the after end stiffened after she entered service. Even by the time QE2 was built it was still an inexact science, the Grim wheels fitted in tandem to the props to improve speed didn't work and fell off! Also, although it is not all that well publicised, the reason for Cunard lengthening their Atlantic crossing times with QM2 is not just to save fuel but to reduce the strain on the Mermaid propulsion pods which are apparently overstressed at full speed necessitating more frequent dry dockings for maintenance and thus less revenue earning time.

Colin

[Martin (Admin)]

I thought we knew everything about Titanic these days, didn't realise there was so much debate about the centre prop!

http://www.encyclopedia-titanica.org/mystery-titanic-central-propeller.html

http://www.titanic-titanic.com/titanic_propellers.shtml

http://titanic-model.com/dc/dcboard.php?az=show_topic&forum=100&topic_id=27355&sub_topic_id=27575&mesg_id=&page=29

http://www.titanichistoricalsociety.net/forum/viewtopic.php?f=117&p=6498

https://www.google.co.uk/search?q=Titanic+center+propellers&client=firefox-a&hs=HWD&sa=X&rls=org.mozilla:en-US:official&channel=rcs&biw=1408&bih=648&tbm=isch&tbo=u&source=univ&ei=htNxVLOTLoL5asygglg&ved=0CDAQsAQ



... and of course...

[mickyrubble]

Hi,
 was at the Titanic exhibition in Belfast and the Titanic definitely had a 3 4 3 arrangement As the 3 3 3 layout produced a lot of vibrations (harmonics)

[roycv]

Hi all I am getting a feeling of deja vu.
Roy

[TheLongBuild]

Hi,
 was at the Titanic exhibition in Belfast and the Titanic definitely had a 3 4 3 arrangement As the 3 3 3 layout produced a lot of vibrations (harmonics)

Why Definitely ?. was there actually a creditable picture to show this ?., the info above is from H & W records ..
I believe it probably was 343 but the notes would suggest otherwise.

Are there no pics of all 3 props at the wreck site ?.

[mickyrubble]

Hi,
 yes Longbuild ,there was a photo of the workers fitting the port prop and the centre shaft has a 4 blades and it is clearly visible

[TheLongBuild]

Hi,
 yes Longbuild ,there was a photo of the workers fitting the port prop and the centre shaft has a 4 blades and it is clearly visible

Again, There are few if any pictures really of the Titanic Being built, they are of the Olympic, there are a few of her being launched.
But not seeing the picture at the Museum I can not really comment either way, you would hope that they have it correct.

http://titanic.su/anatomy-of-the-titanic/270-titanic-fitting-a-propeller.html

Interesting that this site details the outer props but the centre one is labelled " Olympic"

Looking at the shipwreck you would think the centre prop would be visible, wonder if Dr Bollard could nip down and clear the mud away..  Martin have you any connections ..

3, or 4 bladed they are pretty impressive when you see the workers next to them.


Have wanted to go to the Museum Is it worth the Visit, is it a whole day job or just a couple of hours..?

Also just found this site, Looks like they have discussed it in far more detail and still no Definite agreement..   

Makes the moon landings look like they could have happened 

[mickyrubble]

Hi Longbuild,
The Titanic exhibition is well worth a visit,but definitely go mid week when the crowds are less.The Nomadic is now open but i havnt been yet (thinking of building a model of her).HMS Caroline is besides the Nomadic in the next dock along.There is a lot to see and the Titanic part is a full day on its own.
 

[TheLongBuild]

 

[Martin (Admin)]

 
A Complete Guide to Titanic's Engines:  https://youtu.be/4begc_U8ygI?si=5fJ1e5XRauLP_iIy