SELECTION OF THE BEST KIND OF PROPELLING MACHINERY. 231 
Referring to the column headed weight, it would be interesting to know whether this 
is the weight wet or dry, and whether any reserve feed water has been included. 
The weight of the geared-turbine machinery with Scotch boilers for the 2,500 shaft 
horse-power installation is given as 570 tons, or 510 pounds per shaft horse-power which 
is assumed to be the wet weight. This seems too high since we have built a number of 2,600 
shaft horse-power installations which weighed 480 tons or 413 pounds per shaft horse-power. 
We have also built a number of 3,100 shaft horse-power installations which weighed 
560 tons or 404 pounds per shaft horse-power. 
The weight of the 7,200 shaft horse-power installation of geared turbines and water- 
tube boilers is given as 1,140 tons or 354 tons per shaft horse-power. If I am informed cor- 
rectly, the weight of the machinery installation on the President Pierce, which was described 
by Mr. Warriner, is 1,040 tons or 180 pounds per shaft horse-power using the trial power. 
This is considerably less than given in the table. 
The fuel consumption of the 2,500 shaft horse-power geared turbine vessel is given as 
34 tons per day or 1.27 pounds per shaft horse-power. This is surely a very poor perform- 
ance. In view of this, it would be of value to have particulars of the turbine design, steam 
conditions, ete. For Parsons turbines, of good design, we would estimate a fuel consump- 
tion of 1.08 pounds per shaft horse-power, or 29 tons per day. The steam conditions are: 
200 pounds 50 degrees sup. and 28% inches vacuum. 
For the 7,200 shaft horse-power installation the table gives a very much lower fuel con- 
sumption than above or 1 pound per shaft horse-power for a 3,600 shaft horse-power unit. 
Values so far apart do not seem very consistent. 
The fuel consumption of the two-cycle installations are exactly the same as for the four 
cycle. It is my understanding that, for usual designs, the two cycle will use about 7 per 
cent more fuel than the four cycle. 
It is noted in group No. 4 that 3,400 shaft horse-power twin-screw Diesel vessels are 
compared with 4,200 shaft horse-power single-screw steam vessels. With such a wide differ- 
ence of power I cannot see how such a comparison can be of practical value. 
The price of fuel oil for the steam vessels is taken at $10 per ton, whereas the Diesel oil 
price is $11.50, $11.60 and $11.80. The price differential is therefore 15 to 18 per cent 
greater for the Diesel oil, which is rather low. 
Referring to the length of voyage between fueling ports, the table gives distances up to 
20,000 miles. For most of the trade routes used by American vessels, a leg of over 6,000 
miles is not ordinary. Hydrographic Chart No. 1262 illustrates this very clearly. 
Referring to the saving of 22 tons per day given on page 227, this would apply to an 
inefficient steam installation, but for an efficient Parsons turbine I would expect a difference 
of about 1734 tons. 
For the 2,500 shaft horse-power installations, the fuel consumptions of the steam engine 
and turbine are both given as 34 tons. For the 7,200 shaft horse-power installation the steam 
engine consumption is given as 94 tons, whereas the turbine is given as 77 tons. This ap- 
pears inconsistent. 
The differential of $30 per deadweight ton referred to on page 228, would amount to 
$300,000 for a 10,000-ton vessel. No doubt, with such a differential, it will prove profitable 
to install Diesel engines in these hulls. 
Referring to the last paragraph and to Plate 63, this data may be of value in considering 
the particular designs upon which this table was based, but I think it would be misleading 
