# Lloyd’s Register – main engine particulars.



## Avraham Ariel (Sep 1, 2016)

I am attaching an excerpt from LR 1934 (French Edition) in which I
highlighted the particulars of the schooner EMANUEL, missing since
January 1934.
Engine particulars appear in col. 13.
Can any member please help by answering the following questions?
1. What is the significance of the notation NE27 ?
2. The (Diesel) engine is listed as 18 NHP. What is its BHP equivalent?
3. Is there a formula to convert NHP to BHP ?
Thank you


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## YM-Mundrabilla (Mar 29, 2008)

My understanding is that 1 NHP equates to roughly 6 - 7 BHP but open to correction as always.


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## david freeman (Jan 26, 2006)

Avraham Ariel said:


> I am attaching an excerpt from LR 1934 (French Edition) in which I
> highlighted the particulars of the schooner EMANUEL, missing since
> January 1934.
> Engine particulars appear in col. 13.
> ...


why is this thumbnail asking me my name and password, is this ship nostalgia authorisation, or an uninvited guest? What us so special about this LLR or the ship???


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## wightspirit (Feb 15, 2008)

NE = New Engine 1927.

Dave W


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## Freo (Nov 4, 2005)

Nominal horsepower (nhp) is an early 19th-century rule of thumb used to estimate the power of steam engines. It assumed a steam pressure of 7 psi (48 kPa). nhp = 7 × area of piston in square inches × equivalent piston speed in feet per minute/33,000.


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## Avraham Ariel (Sep 1, 2016)

I have completed writing a book about that unfortunate vessel and her crew. I am now short of a few final minor details, including the power of her main engine in modern units of measurement.
It is somewhat strange that the power of a Diesel engine built 1927 was presented in units used by James Watt.
6-7 BHP to 1 NHP seems to be right in this particular case, but I would prefer an authoritative source that can be quoted as a reference. 
By the way, I wrote to the engine builders and was advised they could not locate that particular engine/job in their archive.
Thanks.


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## Peter Short (Apr 13, 2008)

Avraham Ariel said:


> It is somewhat strange that the power of a Diesel engine built 1927 was presented in units used by James Watt.



Avraham,

I wouldn't assume this was a diesel engine. 

I have a Thornycroft catalogue from c.1947 which says they first started making diesel engines in 1931. 

Prior to this they made petrol and oil engines (meaning paraffin, kerosene, lamp oil etc).

Oil engine was once a common term for engines using oil as fuel plus a vapouriser and hot bulb, hot tube or spark ignition.

A true diesel engine draws in pure air on its intake stroke, compresses pure air only, then injects oil at maximum compression i.e. TDC. Self-ignition then occurs at the time of injection.

The oil engine draws in both vaporized fuel plus air on the intake stroke, then compresses this fuel/air mixture. Ignition is therefore dependent on all sorts of variables e.g compression pressure, fuel type, vaporizer heat etc. Such an engine requires pre-heating with a blow lamp before starting.

Unfortunately, the word "Diesel" was unpopular in some quarters and periods (e.g. WW1) and "Oil Engine" was used to describe diesel engines as well. 

BTW, regarding Lloyd's Register, it would pay to find the "Key to Register" at the front of the book. It should explain what the various abbreviations mean, and may (but probably won't) explain N.H.P. 

I looked at a 1879 Lloyd's Register "Key to Register" page, and "NE & B" = New engines and boilers. So I think Dave W is likely correct.

N.H.P. was commonly used with steam traction and portable engines, but I doubt it could be applied to internal combustion engines in the same way.

Here is one description of N.H.P. as applied to steam traction engines:

"Most makers produced a range of sizes referred to by the nominal horsepower (N.H.P.) rating where N.H.P. = D²/10 for single cylinder engines and apparently D²/5 for compound cylinders. In the first instance D was the cylinder diameter in inches and in the second instance D was the high pressure cylinder in inches. These sizes were normally 5, 6, 7 and 8 N.H.P. with outputs at governed speeds of from 155 to 180 R.P.M., amounting to about 25, 30, 35 and 40 brake horse power (B.H.P.) respectively". Traction Engine Design & Construction 1900 - 1930 by G.F.A. Gilbert.

Cars in Britain were for many years taxed according to a nominal horsepower rating of some description, I think based on cylinder bore size. I doubt it helps either, except to show it seems like a flexible term.

It will be interesting to hear what N.H.P. means, applied to a marine I.C. engine. I have never seen it before, but that doesn't mean much.


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## spongebob (Dec 11, 2007)

Peter Short said:


> Avraham,
> 
> I wouldn't assume this was a diesel engine.
> 
> ...


NHP to me has always meant 'nominal horse power' to me and relating to internal combustion engine dimensions , bore and stroke etc. 
Wasn't that the factor that Austin motors used in the 1920's /1930's to fiddle the horsepower of the Austin 7 below the Morris 8's rating and so gain a lower road tax to boost sales?
In boiler parlance Nominal horsepower can be based on heating surface or actual steam output depending on the particular code rules .

Bob


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## Avraham Ariel (Sep 1, 2016)

Thank you Peter for your enlightening reply, and Bob too. 
I tend to agree it may have been a Hot-bulb engine. Weren't those referred to in the olden days as "Semi-diesels"? An old chief engineer once told me he sailed with them in the 1930s.
Back to my question, let me put it another way: Say in 1927, a person owned a schooner of LOA 100 feet ; 140 tons under deck tonnage and 220 tons cargo dwt.
He wanted to fit his vessel with an auxiliary semi-diesel engine that will give her a speed of 7-8 knots in calm weather and smooth sea.
What would have been the power of such engine in BHP?
Thanks again


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## DWB (Sep 4, 2013)

Dear Avraham,
I fear that you will never get a definitive answer to your question about NHP conversion. But I am seeing if I can help. First I have given a potted history of how it came about and then became more of a hindrance than a help. That was all steam stuff and not of direct use to you but may be of interest. 
From Prof A.Jamieson’s “A text book on steam and steam engines” of 1889. - Watt decided that the figure for a horse output was 30,000ft.lb/min. which he adopted as his standard of power, (In fact a horse was nearer 22,000). Prof J. suggests that Watt wanted his engines always to exceed the basic horse power. 
Watt found that the mean steam pressure in his engines was about 7psi and he estimated the power of his engines on that and called it Nominal Horse Power. This was fine until mean pressures began to rise above 7psi, then nominal powers began to differ significantly from actual powers. However, the term NHP was well understood commercially and lasted for a long time, especially for some classes of engine such as agricultural ones (where it is still understood). Some manufacturers began to use NHP for unfair competition. He concludes “…It is fast falling into disuse and should be altogether abandoned.”
Another old steam book, (The Practical Engineers Hand Book of 1890) has several pages on NHP, including a table with 18 different ways of calculating it! It also states that NHP is a commercial term for denoting the size of an engine without regard to the actual power.
So much for the steam side of it, does it apply to Diesel or oil engines?
Bob comments on motor manufacturers using HP to try to gain a car tax advantage, (which I remember my Dad telling me about, we had a Morris 12.) Wikepedia has a good explanation which looks feasible. So NHP was still a moveable feast in the 1930's.
None of my old books use NHP for diesels, all are IHP or BHP. A copy of Munro’s marine engineers’ annual for 1915 has a quite extensive section on Diesel engine ships from about 1911, the one power I noted was IHP. 
However in one section, “Lloyds Rules for the Construction and Survey of Diesel Engines and their Auxiliaries”. It says:- 
“Nominal Horse Power of Diesel Engines. To be inserted in section 29, page 6, of the society’s rules:- The following rule is for determining the nominal horse power of Diesel engines in regulating the fees for their survey vis:-
NHP = NxDxDxsquare root S, all divided by 80….4 cycle single acting engines.
NHP = Same but all divided by 40…..2 cycle single acting.
NHP = Same but all divided by 20…..2 cycle double acting. 
D = Cylinder dia in inches.
S = Stroke in inches ordinary recip engines. Or = 2 x stroke of a Junker type.
N = number of cylinders.”
Lloyds Rules of 1926 state “ The following rule is to be used for determining the NHP of Diesel Engines in regulating the fees for their survey…….”
This is a similar calculation but more detailed. So doesn’t help. 
As these calculations do not include MEP or revs per minute the NHP that they give cannot be used to find IHP.
I have done comparisons of 25 “oil” engine ships where BHP and NHP were given. These are from the 1940 edition of Talbot Booth's Merchant Navy ships, Quite a tome!
The nearest ship that I found to yours size wise, was the ‘Kindiesel’ of 1936. 9.5 Knots, 135’ long, 91 NHP and 300 BHP. Which gives a figure of 3.3 if divided NH into BH. Looking at the other ships, in general, the higher the BHP the bigger the multiplier (largest I recorded was 'Dominion Monarch' at 32,000 BHP; 5056 NHP = x 6.3. The smallest 'Medina' at 456 BHP; 255 NHP = x1.79). So no correlation at all, which is hardly surprising as there will be an enormous variation in operating parameters and sophistication in these engines.
I applied the NHP formula to some real diesel figures from a test card taken on one of my ships. As expected it was rubbish.
I have asked my brother who is into smaller diesels and has various reference books, he cannot help us in any way, only knows what I do about NHP, (including cars).
We have come to the conclusion that, based on the information we have, and from the replies that you have had, there is no correlation between BHP and NHP.
My brother has followed you and sent the schooner and engine details to two stationary engine forums to see if anybody can suggest a suitable horse power.
Hope this ramble is not too long and helps your thinking. Good luck with your book.
Dave. (Hot Fog engineer)


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## Avraham Ariel (Sep 1, 2016)

Dear Dave,

Thank you for your knowledgable and enlightening reply to my query. It gave me an extra pleasure to read it wearing my academic cap (PhD Industrial Engineering, University of New South Wales, 1988. Topic of thesis: the BIBO Ship, my invention).

As to what is HP? I was taught at the Haifa Nautical School, seventy years ago, that HP was coined by James Watt and it was equal to the power to lift 75 kg to a height of one meter in one second. In fact I remember very well that I had a small clash with my physics teacher about it: I challenged the notion that Watt used metric units. It caused a little tumult and was nearly kicked out of the classroom. I solved that riddle today, when sifting old books in my library I came across General Physics by W.L. Whiteley, London 1959, where I read: After experiments, James Watt came to the conclusion that a generous estimate of the rate of working of a good cart horse was 550 ft-lb/sec. Hence an engine is said to be of one horse-power when it can do work at that rate. 
Convert 550 ft-lb/sec to metric units (550 x 0.3048 x 0.45357) and you get 76.04 mtr.kg/sec. The latter figure was rounded down to 75, in order to befit a country that was always metric and never exposed to imperial units!
By the way 550 ft-lb/sec is equal to 33,000 ft.lb/min, which is 10% more than Prof Jamieson’s 30,000. I remember the figure 33,000 also from my engineering course for my Ship Master’s ticket. Could there be a typo in your reply?

You will be surprised to read that I am holding a photocopy of an undated page 6 of an old Lloyd’s Register of Shipping publication (1930s ?) that somebody sent me a few years ago. The middle paragraph reads: The following rule is for determining the nominal horse power of Diesel engines in regulating the fees for their survey, viz. :–
It shows somewhat different formula, but still does not produce the BHP.

I agree with you that there is no correlation between NHP and BHP and that I shall never get a definitive answer to my question about NHP conversion to BHP, unless your brother will come with something.

I suppose the only way to find out the approximate BHP of that particular engine is to search for comparable vessels that were fitted with similar engine. Considering it was a Groningen schooner, I shall have to search the archive of Stichting Maritiem-Historische Databank, that keep records of ships flying the Dutch flag since the early 1800s. https://www.marhisdata.nl.
In fact I am already in contact with those good people and one of their volunteers, a marine engineer, estimated that an engine of 150-200 HP would have done the job for the vessel in question.

Tks again. It is a pleasure corresponding with you. 
Abe


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## eddyw (Nov 6, 2007)

Dear Abe, I think your question assumes that "Emanuel" was a 'motor schooner' rather than an 'auxiliary sailing vessel'. In the former the motor was the main means of propulsion, the sails acting as an additional power source to reduce the engine load and hence fuel costs when winds were favourable. This would require a fairly substantial engine and probably as you mention around 150-200 bhp. In the 'auxiliary sailing vessel' the main source of power was the sail area, the engines installed less powerful, enough to enable the vessel to manoeuvre without sails, avoid towage costs, stem currents, catch tides etc and probably only capable of pushing the hull along at 4-5 knots. This distinction is made by Basil Greenhill in his book, "The Merchant Schooners" Vol 2. So its possible the Thornycroft engine would need to develop much less than the 150-200 bhp needed for full motorised powering. It is interesting that the "Elziena" listed just above the "Emanuel" in the LR extract and with similar hull dimensions was fitted with engines of 36 NHP, double that of 'Emanuel'.


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## Avraham Ariel (Sep 1, 2016)

Dear Eddy,
You hit the nail right on the head. Yes, she was an 'auxiliary sailing vessel'. It seems the answer lies in LR list of such vessels. It will be easier to find a schooner of similar parameters there than in the Dutch data base.
Thank you.


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## david freeman (Jan 26, 2006)

Avraham note/blog~11.
Thanks for putting me in my box, I am still mystified. I Studied and worked in the Marine industry, and my education was slightly less significant than yours DEPT Transport Extra Chiefs Steam and Motor, and then working for 'Auntie' as a ship and engine surveyor, based in the UK.
While in my career I often had to refer to do***ents produced, but the shipping industry, and my ignorance is complete, I must admit, I was aware but never studied the relation ship between NHP and BHP, and my education as a younger person was Imperial Units, and later in life as study for Extra not metric but Unified??? was that the term, again age has caught up with me? Was it 750 foot pounds is was one Horsepower, equals [what as a kilowatt 0.746 of a Kilowatt??? Again I suspect I am talking out of my backside and I duely submit to your PHd


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## Avraham Ariel (Sep 1, 2016)

I salute you Dave and assure you that in my humble opinion Extra Chiefs Steam and Motor is a more respectable degree than many PhDs – and Ship Master tickets – I know. I believe degrees should be judged only by their tangible added value to the community. It seems we both pass this criterion, while – with utmost respect – most PhD theses do not.


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