Titanic's Central Propeller

[Manon Caillard]

What a story for those exploring the Titanic to uncover that centre propeller buried in the seabed. To even
recover the item, how many millions would it be worth?

I saw on another thread that someone asked why they don't use ultrasound to determine the shape of the propeller buried in the seabed, like they did to know how many breaches the iceberg created in the hull. I thought this was a pretty good idea !

Richard also think fitting a three bladed propeller is going backwards in technology performance. As one can see on Lusitania and Mauretania five years older started life with three bladed propellers and soon change over to four blades propellers for improved performance with less vibration and smoother running for passenger ships.

The more a propeller has propeller blades, the more its efficiency will decrease. Hence, in terms of perfomance, I don't believe that a three bladed propeller is "going backwards". Nevertheless, it surely does in terms of comfort. Like Mark said in his article, it's all about finding the balance between those two factors. It also depends on what kind of ship you want to build I guess.

 

[Manon Caillard]

Recently, as in two days ago, Samuel Halpfern released his new article related to the centre propeller. I really recommend it: http://www.titanicology.com/Titanica/ObjectOnTheBarge.pdf

Will definitely check this out, thank you Thomas !

 

[Mike Spooner]

The question I ask why put a four bladed centre propeller on in the first place as on the Olympic?
There is fierce competition in the many shipyards out there and every designer is looking over their shoulder what the others are up to. Was it the Lusitania & Mauritania changing over to four bladed propellers for a smoother running on a passenger ship that made H&W think for a smoother run as the propeller is turning over twice the speed as the outer wing propellers!

 

[Mark Chirnside]

Mark Chirnside and Richard de Kerbrech. As there are NO know photos of Titanic propellers only leads down to speculation what was fitted to Titanic.

We don't need to speculate. Historians need to consider the available evidence and reach a reasoned conclusion. The only evidence to Titanic's propeller configuration is in the H&W documentation I provided way back in 2008.

Mark has strong evidence through a nickname of Andrews note book. Officially the Harland and Wolff drawing office notebook where the three bladed propeller is mention.

I don't rely on the 'Andrews notebook' [sic] as evidence of Titanic at all. Richard's claims to that effect are untrue.

My source for Titanic's propeller configuration is a different document: a H&W engineering notebook - one of a series of volumes.

What the 'Andrews notebook' [sic] does do is document the 3-bladed centre propeller Olympic had fitted in 1913. (As an aside, we have two additional sources as supporting evidence.)

Richard's arguments against a 3-bladed centre propeller on Titanic in 1912 are pretty incoherent given that H&W fitted one to Olympic in 1913!

But Richard is not convinced as he has a poor quality photo showing a four bladed propeller in the Thompson dry dock.

Sam Halpern saw Richard's claims and addressed them in an article Thomas Krom kindly shared. Even though Richard claimed for a fact this photo showed a 4-bladed propeller, there's no evidence it does and Sam argues pretty convincingly for a 3-bladed configuration.

We don't know whether the propeller was intended for Titanic, or not.

Richard also think fitting a three bladed propeller is going backwards in technology performance.

Harland & Wolff didn't think that in 1912-13.

What a story for those exploring the Titanic to uncover that centre propeller buried in the seabed. To even recover the item, how many millions would it be worth?

It's science fiction, unfortunately. Bill Sauder discusses this here:

Best wishes


Mark.

 

[Mike Spooner]

Hi Mark,
I am glad of some your opinions. One question why do think that the Olympic used a four bladed centre propeller and not a three bladed propeller?

 

[Samuel Halpern]

The more a propeller has propeller blades, the more its efficiency will decrease. Hence, in terms of perfomance, I don't believe that a three bladed propeller is "going backwards". Nevertheless, it surely does in terms of comfort. Like Mark said in his article, it's all about finding the balance between those two factors. It also depends on what kind of ship you want to build I guess.

Going backwards in technology? Decisions were made for good reasons at the time they were made. Richard simply ignored the fact that we now have primary source evidence of the propeller configuration on Titanic as well as that on Olympic, including the changes made to Olympic's over the years. The Drawing Office notebook, as Mark said, documented the changes made to Olympic. The relevant pages are shown below. On the right is the original spec for Olympic. The pitch value crossed out and replaced was the modification made in Jan 1912. On the left is the changes made in Mar 1913. Nobody seems to question what was documented here, or the fact that Olympic was fitted with a 3-bladed center prop in 1913, but some just seem to ignore it, just like they ignore the what was documented in the H&W engineering notebook that Mark uncovered in 2008.

 

[Mike Spooner]

Mark or Sam.
I don't question your research into a three bladed centre propeller for Titanic, but rather surprise that nobody took a photo of the propeller installed.
However I have heard that more blades decrease the performance. So what was the theory in using a four bladed over a three bladed for the Olympic ship?

 

[Manon Caillard]

Going backwards in technology? Decisions were made for good reasons at the time they were made. Richard simply ignored the fact that we now have primary source evidence of the propeller configuration on Titanic as well as that on Olympic, including the changes made to Olympic's over the years.

Yes I agree with that, I never said the contrary ! I was simply quoting Mike for the "going backwards in technology" because I don't think that was the case. Like you said, they knew what they were doing.

I'm sorry I probably should have expressed myself better, it led to confusion .

 

[Cam Houseman]

Mark or Sam.
I don't question your research into a three bladed centre propeller for Titanic, but rather surprise that nobody took a photo of the propeller installed.
However I have heard that more blades decrease the performance. So what was the theory in using a four bladed over a three bladed for the Olympic ship?

Didn't Olympic have a three bladed prop for a short time in 1913?

 

[Manon Caillard]

Didn't Olympic have a three bladed prop for a short time in 1913?

Yes she did (until 1919 I think)

 

[Mark Chirnside]

One question why do think that the Olympic used a four bladed centre propeller and not a three bladed propeller?

In that H&W seem to have been experimenting as to the best configuration, I'm not sure it makes a difference which ship had the four-bladed unit or the three-bladed unit, because they would only have comparable data when both ships were in service.

Nobody seems to question what was documented here, or the fact that Olympic was fitted with a 3-bladed center prop in 1913, but some just seem to ignore it, just like they ignore the what was documented in the H&W engineering notebook that Mark uncovered in 2008.

Exactly so. Those who deny either a 3-bladed centre propeller for Titanic in 1912 or a 3-bladed centre propeller for Olympic in 1913 do so on the basis of deliberate ignorance of the primary source evidence.

By the way, as Bill Sauder states in the video I linked to, he has evidence a 3-bladed centre propeller WAS cast and the weight of the unit is even documented.

Yes she did (until 1919 I think)

We have evidence a 3-bladed centre propeller was fitted in 1913 and then a 4-bladed centre propeller was photographed in 1919 and installed for the 1919-20 refit.

There may have been a further change in between but we do not have evidence of it.

Best wishes


Mark

 

[Mike Spooner]

Perhaps I can give a reason why fit a less efficient four bladed over a three bladed propeller in the first place. That will come from two other ships built before Olympic.
Laurentic and Megantic both are the same size, yet Laurentic has the same combination as the Olympic three engines on a smaller scale. However did they find the three bladed centre propeller produce more vibration that of the two screwed propeller on the Megantic? So to sacrifice some efficient less vibration for passenger comfort, where a four bladed propeller is fitted to Olympic. However I can see the logic fitting a three bladed centre propeller to Titanic for increase efficient. I don't see any complains from Titanic passengers of vibration problems. Yet at of the day the four bladed was more in favour as fitted to Britannic and to Olympic after the WAR years.

 

[Thomas Krom]

I don't see any complains from Titanic passengers of vibration problems.

On the 14th of April, when the Titanic was nearing a speed of 22 and a half knots, vibration problems were noted by multiple passengers which either were aft at the time or had their stateroom near the stern (George Rheims near the first class smoking room, Edith Haisman, Mahala Douglass at the after Louis XIV staircase to name a few people).

 

[Mike Spooner]

On the 14th of April, when the Titanic was nearing a speed of 22 and a half knots, vibration problems were noted by multiple passengers which either were aft at the time or had their stateroom near the stern (George Rheims near the first class smoking room, Edith Haisman, Mahala Douglass at the after Louis XIV staircase to name a few people).

Would you think that was a feasible reason to change over to a four bladed propeller? Or did Olympic with a four bladed propeller have that problem at 22 knots plus?

 

[Cam Houseman]

Yes she did (until 1919 I think)

In that H&W seem to have been experimenting as to the best configuration, I'm not sure it makes a difference which ship had the four-bladed unit or the three-bladed unit, because they would only have comparable data when both ships were in service.



Exactly so. Those who deny either a 3-bladed centre propeller for Titanic in 1912 or a 3-bladed centre propeller for Olympic in 1913 do so on the basis of deliberate ignorance of the primary source evidence.

By the way, as Bill Sauder states in the video I linked to, he has evidence a 3-bladed centre propeller WAS cast and the weight of the unit is even documented.


We have evidence a 3-bladed centre propeller was fitted in 1913 and then a 4-bladed centre propeller was photographed in 1919 and installed for the 1919-20 refit.

There may have been a further change in between but we do not have evidence of it.

Best wishes


Mark

Thanks a ton!