# motor question!



## barrys (Oct 5, 2008)

as a steam turbine man, having watched an old film, San Demetrio, about a motor oiltanker returning from the states to london full of petrol around 1940-44 its motor was it seems 5 or 7 cyls, overhead camshaft with the camshaft moving up and across to give reversal of the engine,main operating platform directly alongside / attached to the main engine, air start on operating wheel, ,what was that engine, it seemed quite efficient to me but never having sailed on one! i await your comments, regards to you all, Barry.


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## eldersuk (Oct 24, 2005)

Could be a B&W four stroke where the reversing gear lifted the cam followers off the cams and simultaneously moved the camshaft along so that the astern cams were aligned under the followers. A bit agricultural but quite ingenious.

Derek


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## surfaceblow (Jan 16, 2008)

While this was nothing about the engine on the San Demetrio there is an eye witness account of the voyage by John Lewis Jones who was an apprentice at the time. 

http://www.rhiw.com/y_mor/capt_j_l_jones/san_demetrio/san_demetrio.htm


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## barrys (Oct 5, 2008)

*b&w diesel*

Thanks Derek, yes thats the one very clever and watching it operate a work of art , we did have a Paxman diesel geni set for emergencies, speaking to a chief who had them as main engines he said they had to rebuild them just to get back from trip and i can believe that! thanks for your answer all the best Barry.


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## barrys (Oct 5, 2008)

*san demitrio*

surfaceblow many thanks for that i have just printed it off and will have a good read, regards barry.


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## blurb10 (Mar 23, 2007)

Would suggest this is almost certainly a Werkspoor 4 stroke engine, which
Eagle Oil favoured at that time.
Regards, Bob Blurb10


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## K urgess (Aug 14, 2006)

There's a little wartime booklet called "The Saga of San Demetrio" by F. Tennyson Jesse. First published in 1942 by HMSO.
The specifications are laid out on pages 6 & 7 -
"_M.V. San Demetrio_ was, as the initials in front of her name imply, a motor-driven ship. She was a tanker of 8,073 tons gross and 4,815 net, 463 feet in length, and she was fitted with a *Kincaid* engine, which is an eight-cylinder supercharged engine of 502 N.H.P. When fully laden, she could carry between 11,000 and 12,000 tons of petrol. She was a single screw vessel, and her engines gave a speed of about twelve knots in fine weather and when she was fully laden."
The action took place in 1940, Miramar has the ship as torpedoed and sunk in 1942 well after she was repaired and back in service. The film was made in 1943. In which case the engine you saw was not the one she was fitted with but the stand-in used in the film. 
I can't find any record of which ship was used but maybe someone in the crew can help.
Cheers
Kris


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## Derek Roger (Feb 19, 2005)

barrys said:


> Thanks Derek, yes thats the one very clever and watching it operate a work of art , we did have a Paxman diesel geni set for emergencies, speaking to a chief who had them as main engines he said they had to rebuild them just to get back from trip and i can believe that! thanks for your answer all the best Barry.


Paxmans " the Nightmare returns " lol Derek


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## Abbeywood. (Aug 7, 2009)

barrys said:


> Thanks Derek, yes thats the one very clever and watching it operate a work of art , we did have a Paxman diesel geni set for emergencies, speaking to a chief who had them as main engines he said they had to rebuild them just to get back from trip and i can believe that! thanks for your answer all the best Barry.


I sincerely hope that you had no, or very few, emergencies then. 
My sympathies go out to the CE to whom you referred. 
The RN loved them, but then they had umpteen matelots to throw at the job when things went pear-shaped
Useful spanner was a 9/16" A/F combination, tied to your wrist. If it fell into the 'vee' it was a work-up to get it back.


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## Abbeywood. (Aug 7, 2009)

Marconi Sahib said:


> There's a little wartime booklet called "The Saga of San Demetrio" by F. Tennyson Jesse. First published in 1942 by HMSO.
> The specifications are laid out on pages 6 & 7 -
> "_M.V. San Demetrio_ was, as the initials in front of her name imply, a motor-driven ship. She was a tanker of 8,073 tons gross and 4,815 net, 463 feet in length, and she was fitted with a *Kincaid* engine, which is an eight-cylinder supercharged engine of 502 N.H.P. When fully laden, she could carry between 11,000 and 12,000 tons of petrol. She was a single screw vessel, and her engines gave a speed of about twelve knots in fine weather and when she was fully laden."
> The action took place in 1940, Miramar has the ship as torpedoed and sunk in 1942 well after she was repaired and back in service. The film was made in 1943. In which case the engine you saw was not the one she was fitted with but the stand-in used in the film.
> ...


Think you'll find that the 'on-screen' main engine was a B&W built under licence by Kincaids. Cant believe that the net HP was only 502. Is there a zero missing somewhere. ?


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## K urgess (Aug 14, 2006)

502 net HP is the figure given in the wartime booklet.
Merchant Ships 1942 by Talbot Booth gives 3,500 BHP.
There's more here -
http://www.shipsnostalgia.com/showthread.php?p=372182


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## Bob_F (Jun 14, 2004)

Marconi Sahib said:


> 502 net HP is the figure given in the wartime booklet.
> Merchant Ships 1942 by Talbot Booth gives 3,500 BHP.
> There's more here -
> http://www.shipsnostalgia.com/showthread.php?p=372182


N.H.P. is an abbreviation for Nominal Horse Power not Net H.P. I have been trying to remember how this figure is reached.

Cheers.

Bob_F


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## Duncan112 (Dec 28, 2006)

NHP is a function of the cylinder area and piston speed, can't remember what though.


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## K urgess (Aug 14, 2006)

That was me following Abbeywood's post. I should have typed N.H.P. as in my original post.


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## hamishb (Oct 23, 2008)

*N.h.p.*



Duncan112 said:


> NHP is a function of the cylinder area and piston speed, can't remember what though.


Hi guys, Nominal Horse Power is adopted in order to express the capacity of an engine, the elements being confined to dimensions of steam cylinder, and a convensional pressure of steam, and speed of piston.
To Compute Horse power

Non Condensing D2 v and condensing D2 v = HP

1000 1400 
D Represents the Diameter of the cylinder in inches, and v = velocity of piston in feet per minute 

Non-Condensing is Based on a uniform steam pressure of60 pounds per square inch, cut offat .5 stroke, deductingone sixth for friction and losses, with a meanvelocity of piston, ranging from 250 to 450 feet per minute.

Condensing is based on a uniform steam pressure of 30 pounds per square inch, cut off at .5 stroke, deductingone fifth for friction and losses, with a mean velocity of piston of 300 feet per minutefor an engine of short stroke, andof 400 feet fot one of long stroke. 

Taken from a wee book , on the spine is the name HASWELL and is the 
Twenty First Edition Published 1867 so info might be a bit dated. 
Who remembers those Feet and Inches thingys.
Hamish.


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## Hamish Mackintosh (Jan 5, 2006)

surfaceblow said:


> While this was nothing about the engine on the San Demetrio there is an eye witness account of the voyage by John Lewis Jones who was an apprentice at the time.
> 
> http://www.rhiw.com/y_mor/capt_j_l_jones/san_demetrio/san_demetrio.htm


It is interesting to note that Mr Jones makes scant mention of the man in charge, Second mate Hawkins, and in the accolades at the end only himself and the Chief engineer are mentioned


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## Billieboy (May 18, 2009)

hamishb said:


> Hi guys, Nominal Horse Power is adopted in order to express the capacity of an engine, the elements being confined to dimensions of steam cylinder, and a convensional pressure of steam, and speed of piston.
> To Compute Horse power
> 
> Non Condensing D2 v and condensing D2 v = HP
> ...


That must be the original, "Puffer", handbook Hamish! That sort of information is NEVER dated.


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## Abbeywood. (Aug 7, 2009)

My thanks to the 'Marconi Sahib; and others, for clarifying the description of NHP, (i.e. Nominal, not Net).
Would I be correct, that the given figure of 502 NHP would be applied to the output of one cylinder and that therefore the engine actually produced 4016 
HP, or am I still about 2 days behind everyone else, as in all probability.


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