558 



Popular Science Monthly 



which is shown in the illustra- 

 tion on page 556 of this 

 issue. This has been in 

 use for more than four 

 years and is still giv- 

 ing satisfactory 

 service. 



The Cement-Gun Rod Re-enforcement 

 The T-hars used in the side of the concrete ship are 

 made by shooting the material into place. The spacer 

 bars have holes through which are inserted short rods 

 with hooks to carry the horizontal bars on which the 

 three layers of re-enforcing wires are hung. By this 

 means the wire is kept always in its proper relation 



Advantages of 

 Concrete Ships 



Re-enforced con- 

 crete barges seem to 

 have given good 

 service, so that the 

 present problem of 

 building self-pro- 

 pelled ships of four- 

 or five-thousand 

 tons capacity is one 

 of construction 

 methods and of tak- 

 ing care of the severe 

 strains of ocean 

 travel and the vibra- 

 tion of the engines. 

 These conditions 

 met, concrete has 

 many advantages 

 not enjoyed by 



either wood or steel. Concrete ships would 

 be fireproof and would require less main- 

 tenance than steel vessels because 

 of the elimination of scraping and Hatch coammq 



painting to 

 avoid deteri- 

 oration due 

 to rusting. 

 Also, their 

 bottoms 

 would need 

 to be cleaned 

 less often be- 

 cause sea 

 growths do 

 not attach 

 themselves so 

 readily to 

 concrete as to 

 steel and 

 wood. Some 

 advocates of 

 the concrete 

 vessel claim 

 that it can be 

 built at less 

 cost than a 

 ship of steel 

 or wood, that 

 it has a 



longer life than 

 either and that less 

 skilled labor is re- 

 quired. While this 

 may be true in the 

 case of small barges 

 and the like on 

 which actual cost 

 figures are available, 

 it remains to be 

 proved in the case 

 of the large ocean- 

 going freighter. The 

 standardized cargo 

 boat of either steel 

 or wood as planned 

 by our Shipping 

 Board will be built 

 in much less time 

 than any other ships 

 constructed hereto- 

 fore. 



Following previ- 

 ous re-enforced con- 

 crete construction 

 methods, the pro- 

 posed concrete ves- 

 sels may be built 

 along two general 

 lines — one by the use of forms, as in most 

 building work, and the other by the 



A Simple Con- 

 crete Barge 



Below: Note the 

 single side hull and 

 double bottom 

 construction; also 

 the form of the three 

 vertical deck sup- 

 ports and the beams 



Transverse Section 



Through Deck and 



Part of. Hatch 



Above we have a good 

 illustration of the man- 

 ner in which the con- 

 struction of the concrete 

 boats will follow the 

 usual methods of con- 

 crete building in regard 

 to re-enforcing. Note 

 the wood bumper 

 stringer bolted to the 

 concrete hull to ward 

 off collisions, which 

 might tend to crack the 

 concreteand cause a leak 



