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PROPULSION 



The plans of the SUITLAND show her driven by a single screw, turned 

 by a steam reciprocating engine powered by Scotch boilers. This is a power 

 plant considered old-fashioned and inefficient in many respects, but compared 

 with diesel it offers the following advantages: 



(1) Low first cost 



(2) Low cost and wide availability of fuel 



(3) Wide availability of experienced operating personnel, and relatively 

 simple mechanical operation 



(4) Low upkeep costs 



(5) Wide availability of repair facilities, and minimum requirements for 

 spare parts 



(6) Low depreciation. Some oceanographic vessels in service today 

 have had diesel engines replaced up to three times in 15 years. 



(7) Flexibility of operation. Low speeds for trawling or station-keeping 

 are being easily accomplished. 



(8) Minimized vibration. This is an important point where the work 

 requires use of galvanometers, microscopes, etc. All auxiliary 

 machinery can be turbine-driven. 



(9) Availability of distilled water 



(10) Availability of steam for operating winches. 

 To be weighed against these advantages are the greater weight of the installation 

 (which is not such an important problem in a vessel not carrying cargo), lower 

 fuel efficiency, and need for a larger engineroom force. A careful study should 

 be made of union manning scales. Coast Guard requirements, fuel costs, and 

 prevailing wages in the home port before reaching a final decision as to power 

 plant, since conditions may vary with localities. 



With regard to the use of a single screw versus twin screws, a reliable 

 power plant needs only the single screw, and the possibility of entangling gear 

 is greatly reduced. In this connection it is pointed out that the Navy, as report- 

 ed in the May 1952 Bureau of Ships "Journal", has recently siettled on single- 

 screw installations for all jobs under 30,000 SHP. Since the SUITLAND is to 

 cruise at 10 knots and have a top speed of 12, her power will be around one- 

 fiftieth of this figure. 



ICE BREAKING ABILITY 



In a vessel as small as the SUITLAND, addition of ice navigation features 

 probably represents addition of considerable weight and first cost, and the added 

 weight will be useless 85% or 90% of the time. She will not have the power to 

 be an out-and-out icebreaker; rather, she will be a semi-icebreaker, and there 

 is no such thing as semi-ice. Possession of strengthening will only be an invi- 

 tation to place the vessel in situations from which she will be unable to extricate 

 herself. 



If an oceanographic vessel for work in ice is required, consideration 

 should be given to modifying one of the existing Wind-class ice-breakers and 

 adding the necessary facilities for oceanographic work. Only with a vessel of 

 this tonnage, horsepower, lines, and thickness of plating is there assurance of 

 safe operation in ice, 



DISCUSSION: B.K. Couper 



Officially, the Bureau of Ships has no opinion on the subject of the design 



