Range and Endurance

[A. Gabriel]

So far to my knowledge, no data is available (or these values have not been determined) for the range and endurance of Titanic and her sisters, unless these exist in volumes I have yet to gain access to perhaps. In the interests of obtaining or deriving even more information for the class — one can never say too much about them after all — how would one go about calculating for these specs?

 

[Mark Chirnside]

When you say 'range and endurance', do you want to know the total distance they could cover before running out of fuel? If so, this can be calculated for various speeds and loading conditions.

Best wishes

Mark.

 

[A. Gabriel]

Yes, yes that is precisely what I am looking for Mr Chirnside. Where can the relevant equations and/or data be found, that I may attempt the calculations?

 

[Mike Spooner]

That like asking what a length of a piece string is? The speed, weather condition and type of coal been used all have to be considered.

 

[A. Gabriel]

Evidently my lack of knowledge in this area shows, unsurprising given this is so far removed from my usual field of study (then again, what bearing has chemistry where the Olympic-class is concerned?). Regardless, let me try my hand at a crude rendering of the calculations to see how far off the mark my results end up being.

Titanic’s coal bunkers had a capacity of 6611 tons. Borrowing the value of average daily consumption, 620 tons per day at constant 21.7 knots, from Olympic’s maiden voyage, this would be coal enough for 10 days and 16 hours. If I instead use the 850 tons/day value from Olympic’s wartime service (38’6” draught, 22.5 knots), this works out to be coal enough for 7 days, 18 hours, and 40 minutes at the named speed. Here I have divided amount of coal by the average daily consumption to estimate how long the ship may steam without refueling.

Now I make the assumption that the distance = speed * time formula is valid for calculating the range, i.e. assume ideal currentless conditions, as scientists are wont to do. The values I get come out as 5553 n.m. at 620 tons/day and 21.7 knots, and 4200 n.m. at 850 tons/day at 22.5 knots. (I had to include the periods — nm means nanometers in my usual line of study!)

Have I committed gross oversimplification or missed any factors in this reckoning?

 

[Mark Chirnside]

A. Gabriel

Real life scenarios can be more complicated but - as a basic calculation - you can obtain an approximate idea. A ship's state of loading will change as coal, stores and so forth are used up, so it will not remain constant. Nor will the weather conditions. Therefore we have to opt for specific conditions for the calculation. Provided they're defined, I see no issue or problem.

If we assumed Olympic was loaded to the same draft as on her maiden voyage and run at 16 knots then her daily (24 hour) coal consumption for all purposes was 343 tons. Therefore, using your 6,611 tons capacity, she could run for about 19.3 days and cover about 7,400 miles.

Best wishes

Mark.

 

[Mike Spooner]

The quality of coal comes into the calculation to how much is burnt per day. Heating values referred as Calorific Value.
Best coal was Welsh grade 1.However seen the national coal strike was in progress leading to a shortness of coal and ships laid up. One could not be too choosy here. As Newcastle, Scotch and America coal were a softer grade burning at a quicker rate. The following BTU rating.
Best Welsh coal 16,000
Average Newcastle coal 14,900
Average Derbyshire and Lancashire coal13,900
Average USA coal 14.300
Average Scotch coal 14,200.
What was loaded on the Titanic in Southampton could of well been a bit of mix bag.
25th March in Belfast 3,000 tons of Scotch coal loaded. On arrival on 4th April in Southampton how much was burnt? If 1880 tons was load from coaling barges and a further 4,427 tons robbed from other ships bring extra coal over from America. Ships under IMMC. St Louis, New York, Philadelphia, Oceanic and Majestic. which well been USA coal. Total now 6,307. But a further 415 tons were burnt whist in Southampton leaving on the 10 April with 5,892 tons about 11% down from max at 6,611 tons
If burning at 650 tons per day which I very much doubt and was a lower figure due to all boilers not been lite. With 5,892 tons on board that give her just over 9 days sailing. Well in. O though Mark quotes 343 tons at 16 knots seems to be a rather low figure for speed? Or is there more I have missed!

 

[Mark Chirnside]

Mike

The figure of 16 knots is an example figure I used to illustrate a calculation for A. Gabriel.

Best wishes

Mark.