234 SELECTION OF THE BEST KIND OF PROPELLING MACHINERY. 
and weight as two different factors, and if the two are treated independently then I do not 
think Mr. Smith is taking issue with this statement. 
Referring to Mr. Smith’s comments on the data listed on Plate 63, it was not the author’s 
intention to go into great detail of the various installations, as this would require too much 
time and space. I have taken fair average examples of ships now in operation. 
The fuel consumption on the 2,500-horse-power turbine units is very liberal and might 
be improved upon, but I do not think it would be a fair comparison to take the best figure 
that a steamer could.do and compare that with a Diesel engine, because invariably the Diesel 
engine will come nearer her fuel guarantee than the steamer. 
The author has not found that geared-turbine units of 2,500 horse-power and less are 
any more efficient than steam reciprocating engines; it is only in units of greater horse-power 
that the turbine begins to be much more efficient. 
The weights given are net, no reserve water is included, but the allowance for reserve 
feed per day is given in another column. 
I note Mr. Smith considers the weights too high. In this respect I would call attention 
to Mr. Shaw’s remarks. Mr. Shaw thinks these weights are light. There seems to be an 
honest difference of opinion, but nothing has been presented to cause any change of opinion 
on my part. 
The fuel consumption of the 2,500 horse-power is very liberal; the designed steam con- 
ditions were 200 pounds dry steam, 28 inches vacuum. While the 34 tons might be im- 
proved upon, this is what actually is being done. If the consumption is reduced to 29 tons 
per day, this will not change the author’s conclusions. 
I would expect a much lower steam consumption per horse-power on a 7,200-horse- 
power unit than I would on a 2,500-horse-power unit, and I don’t think the values given in 
the paper are far wrong. 
Referring to group four, a comparison can be made by taking the speed given for each 
type and figuring the time required between each port. 
The prices for fuel oil are actual quotations to an operating company. Referring to 
length of voyage, while 6,000 miles is fair, still 9,000 miles is not unusual in the far eastern 
trade, and if an operator does not want to pay a higher price for fuel in the East, it means 
taking enough on board for 18,000 miles. 
In reply to Mr. Shaw, I explained in the paper my reasons for not giving the extra earn- 
ings of the motor ship due to increased cargo space in dollars and cents instead of in tons. 
It is, however, a very simple matter to select the trade and then substitute dollars for tons. 
Referring to the comparison between the revolutions of the motor ship and steam ship, 
the author had in mind a single-screw steam ship and twin-screw motor ship, because in all 
the cases under consideration, with the exception of the passenger vessel, it would be possi- 
ble to power the ships on a single screw with steam, and the point I wish to make was that 
in many cases it would be possible to power a steamship on a single screw when it would be 
necessary to use twin screws on a motor ship, and the advantages of a single-screw ship over 
a twin-screw ship are such that steam should be given this ¢redit. 
With reference to the comparison between the single-screw steamer Prinsessan Ingeborg 
and the single-screw motor ship Suecia, Mr. Shaw’s figures are not convincing, because there 
is nothing to show that both hulls are equally efficient, and a comparison of the two, correct- 
ing for the displacement only, is not sufficient; the ships have different block coefficients, that 
of the steamer being larger. This would indicate that the steamship is a more difficult ship 
to propel. 
