Titanic's Central Propeller

[Richard Woolcock]

Hi Mark
Just read your article on the Titanic's central propeller , was very interesting. When I was at Belfast, PRONI were extremely helpful and patient supplying stuff but a few things are still held by Harland & Wolff themselves and you needed there permission to examine them. Was curious, did they give any idea why these particular items are held by Harland & Wolff. Not that I have any objection, it is their material after all!!!

Regards

Richard

[Moderator's Note: This post, originally posted in a separate topic, has been moved to the one which is discussing articles submitted to ET. JDT]

 

[Michael H. Standart]

For the record, the article Richard is talking about may be accessed at

The mystery of Titanic's central propeller

A unique engineering notebook helps unravel an enduring Titanic mystery

www.encyclopedia-titanica.org

For anybody here not a member of TIS and who does not recieve a copy of Voyage, here's your chance to read this outstanding piece of research.

 

[Mark Chirnside]

I appreciate the very kind comments, Richard and Michael.

I am not sure I can answer your query, Richard. I assume it is merely company policy.

Best wishes,

Mark.

 

[Commodore Urban]

You just blew my mind! Wow!

 

[Gerhard Schreurs]

Dear Mr. Woolcock and Community,

Intriguing topic. The notebook seems to give a valuable clue, although no dates of original layouts and changes are entered. Also, the writing is not 100% discernible at certain places. Perhaps a separate enlargement of the bottom half of the left page would be helpful.
At the moment, i read the data like this:

Project no. 400 (Olympic)
Reciprocating
Propeller diameter: 23'-6"
Blade pitch: 33'-6" (changed into 34'-6")
Blade area: 160 sq. ft.
Blades: 3
Turbine
Propeller diameter: 16'-6"
Blade pitch: 14'-6"
Blade area: 120 sq. ft.
Blades: 4

Project 401 (Titanic)
Reciprocating
Propeller diameter: 23'-6"
Blade pitch: 34'-6"(changed into 35')
Blade area: 160 sq. ft.
Blades: 3
Turbine
Propeller diameter: 17'-0" or 17'-6" (hard to make out in the writing)
Blade pitch: 14'-6"
Blade area: 120 sq. ft.
Blades: 3

The 3-bladed prop on 401's turbine shaft is one foot larger in diameter, yet each blade still has a surface area of 120 square feet, meaning that the blades have a slightly more slender shape. 360 square feet (3 blades) thrashing through the water at a certain rpm require less horsepower than driving 480 square feet ( 4 blades) through the water, with the same pitch at the same rpm. So, the 3 bladed prop may have been an experiment to allow the turbine to run at a higher rpm, possibly to improve its efficiency or to lighten its load. Increasing the blade pitch of the two wing props would mean a higher load on the reciprocating engines and would reduce their rpm, saving steam (unless the boilers would be made to generate more psi to compensate). Less steam through the reciprocating engine would mean less LP steam through the turbine, making it necessary to lighten its load in order not to lose too much rpm.

Kind regards, greetings from the Netherlands

 

[Jeff H]

now this is an interesting bit of history.
even more interesting is that there is one photo that I've found of one of the sisters, showing a 4 bladed central prop, where the hull seams do not line up with either the Olympic or Brittanic.
that image is an old stock image historic-1912-image-of-rms-titanic-rudder-and-propellors-with-group-of-ship-workers-in-the-huge-dry-dock-construction-site-adding-scale-to-the-huge-ocean-liner-harland-and-wolff-shipyard-belfast-uk-PK06RX.jpg (1300×1089) (alamy.com)

the specific seam I am looking at is on the plate running from the trailing edge of the outrunner to the leading edge of the prop cutout, both Olympic and Brittanic have a vertical seam in that plate

 

[Thomas Krom]

now this is an interesting bit of history.
even more interesting is that there is one photo that I've found of one of the sisters, showing a 4 bladed central prop, where the hull seams do not line up with either the Olympic or Brittanic.
that image is an old stock image historic-1912-image-of-rms-titanic-rudder-and-propellors-with-group-of-ship-workers-in-the-huge-dry-dock-construction-site-adding-scale-to-the-huge-ocean-liner-harland-and-wolff-shipyard-belfast-uk-PK06RX.jpg (1300×1089) (alamy.com)

the specific seam I am looking at is on the plate running from the trailing edge of the outrunner to the leading edge of the prop cutout, both Olympic and Brittanic have a vertical seam in that plate

Here is the original photograph taken by Robert Welch, Harland and Wolff their personal photographer. The catalogue number in the right corner at the bottom (1512) is part of a set of Olympic in the Thompson Graving dock in April 1911. This means that could have impossibly come from the Titanic, which was launched a bit more than a month later. Robert Welch took a total of 5 pictures up close of the Olympic in drydock numbered 1511 to 1515. Here are the other pictures if you are intrested to see them.

1511. Triple propeller arrangement and rudder, portside view from dock floor, with three figures.

1513 Triple propeller arrangement, rudder and underside of counter from port side of graving dock.

1514 Port stern profile of counter, rudder and centre propeller from side of graving dock.

1515 Port bow profile from side of graving dock with pump house and chimney in background.

 

[Tim Gerard]

Today, the propellers are buried in the mud on the ocean floor, right? How easy or possible would it be for a future expedition to use some kind of fancy sonar or something to "see" the propeller through the mud and determine for sure if it's 3 or 4 blades? I remember seeing a documentary about an expedition in the 90s that looked for the iceberg damage, and they used sonar or something to "look" at the part of the starboard bow section that's buried in the ocean floor and confirmed the damage to be a series of slits. Assuming they can get funding (which I imagine would be the biggest hurdle), I'm just curious how feasible it would be.

 

[Kate Powell]

Thank you for sharing the images, Thomas.

 

[Jeff H]

Thomas,
thank you for the correction.
And the images
Jeff

 

[Steven Christian]

Yes, nice pics. Don't recall seeing those before. Good find!

 

[Manon Caillard]

Hello everyone !

Does someone know where to see / where to get a copy of Andrews notebook ? Could I found it digitized on the internet ? Or does someone have pictures of it ?

Hoping you can help me
Cheers,

Manon

 

[Thomas Krom]

Does someone know where to see / where to get a copy of Andrews notebook ?

It isn't his notebook, it is a nickname. The book is a specification book used by the drawing offices, it contains alterations during the 1912-1913 refit. But I do have it for you.

 

[Mike Spooner]

Interesting to see the centre propeller has come to light again, as only in the BTS ADB summer journal has raised the questions whether it was a four or three blade centre propeller by two well known Titanic authors.
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. 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. But Richard is not convinced as he has a poor quality photo showing a four bladed propeller in the Thompson dry dock. 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.
In fact the whole article on propeller design in ADB journal makes interesting reading indeed.
It does mention a reproduced copies of Andrews Notebook is available from Lagan Boat Company. Has anyone read this book?
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?

 

[Thomas Krom]

he has a poor quality photo showing a four bladed propeller in the Thompson dry dock.

Did he made this very picture publicly available?

It does mention a reproduced copies of Andrews Notebook is available from Lagan Boat Company. Has anyone read this book?

I have the very specification book, and I do not get why it has that nickname. It does not contain any notes, during maiden voyages (both westbound and eastbound) Thomas Andrews Jr had three notebooks: one for the Oceanic Steam Navigation Company/White Star Line, one for Harland and Wolff and one for himself. His notes had nothing to do with the things that are in the specification book.



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