SUPERHEATED STEAM IN MARINE PRACTICE. 187 



now building in England eight geared turbine ships ranging from 3,600 to 10,000 

 shaft horse-power (averaging about 5,500), which are to be equipped with super- 

 heaters. It is probable that the degree of superheat used will be from 125° up- 

 ward. Geared turbine installations with superheated steam are receiving consid- 

 erable attention in the United States. There are a number of specifications now out 

 which provide for this combination. It is probably true that some designs of tur- 

 bine may not be able to use as high a degree of superheat as others, due to condi- 

 tions of design and construction. Thousands of horse-power of turbines in shore 

 installations are operating with moderate and high degrees of superheat, without 

 any trouble. 



DIFFICULTIES TO BE OVERCOME. 



59. Difficulties have existed chiefly as regards: — 

 1st. Lubrication. 



2d. Filtering. 



3d. Superheater design. 



4th. Superheater maintenance and repairs. 



5th. Engine performance. 



60. That these difficulties have been overcome is evidenced by the increasing 

 interest in superheaters by shipowners and builders. These points have been dwelt 

 upon quite fully in the preceding paragraphs of this paper. 



61. With the wider use of turbines as mentioned elsewhere in this paper, the 

 use of superheated steam will receive added impetus. This may be taken as an in- 

 dication that the superheating apparatus has been developed to a commercially at- 

 tractive standpoint. 



62. There can be po question but what the earlier difficulties encountered with 

 superheated steam have remained vividly in the minds of a great many marine en- 

 gineers and some shipowners. It should not, however, be accepted that these dif- 

 ficulties necessarily exist today ; at least the progressive engineer should inquire as 

 to whether it is now possible for him to make use of highly superheated steam satis- 

 factorily and avoid, without radical change in design, the troubles which were 

 earlier experienced. Marine engineers, like those in other branches of engineering, 

 are not in all cases inclined to take this point of view. Some find it easier to dis- 

 miss the subject with the thought that insurmountable difficulties are bound to 

 come up and that it is easier "to let the other fellows do the experimenting." Such 

 a position in this matter is that "any economy will be to the owner's benefit, but any 

 trouble from the apparatus will be to the engineer's discredit." The attitude thus 

 expressed is greatly to be regretted, as it indicates that such a one is inclined to 

 believe that progress has reached its highest point, and that from now on we can 

 expect little in the line of added efficiency and economy. The writer believes, 

 however, that men holding this point of view are less frequently met with than 

 formerly, and that the superintending engineer of today is becoming very open- 

 minded in problems which mean for advance in marine engineering. 



