METHOD OF CONSTRUCTION OF CONCRETE SHIPS. 25 



the ship run full speed astern for ten minutes. With the ship going full speed ahead, 

 reversing the engines brought her to a standstill in three minvites. 



These are the standard tests made on the trial trip of any ship. Both the 

 Polias and the Atlantus handled very much as a steel ship of similar size and lines 

 and with the same type engines would handle. The chief difference which was 

 noticed by everyone on the trial boards was the marked lack of vibration on the con- 

 crete ship. One other point, which was found in both concrete ships, is that they 

 backed nearly straight and can be steered slightly while backing. A steel ship 

 with a right-handed engine always swings her stern to port when backing, and 

 usually does not answer to her helm. Why the concrete ship should show this dif- 

 ference is not known, and it may not hold for the other ships, but it is a point com- 

 mon to both of the Emergency Fleet Corporation's concrete ships which have so 

 far been tested. 



COST AND PROGRESS RECORDS. 



Weekly progress and cost reports were received from all concrete shipyards. 

 A card of accounts was prepared upon which the cost was reported segregated in 

 fifteen main items. The report of progress and cost includes a statement of the 

 direct labor charge on each of these items, the man-hours of work done on each 

 item for the week covered by the report, and the quantity of work done on each item. 

 In addition to the fifteen items of hull construction, report is also made on the dis- 

 tributed prehandling expenses of chief materials entering into the construction of 

 the hull. The setting of propellers, line shaft and rudders is also covered by this 

 report, for although this work is really part of the outfitting, a large proportion of 

 it may be done while the hull is still on the ways. 



Each item of construction has been analyzed on the basis of total man-hours 

 necessary for its completion and a comparative value set on each, so that the total 

 of the items adds to lOO. If the figures showing the percentage of each item erected 

 is multiplied by this so-called "unit value" and the product of these terms are added, 

 the sum will be the percentage complete of the entire hull. 



TOTAL AND UNIT COST. 



At the time of writing, total costs are available on the hulls, of four 7,500 D. 

 W. T. reinforced concrete oil tankers. The net cost for the hull alone ranges from 

 about $600,000 to $700,000. The relative distribution of this cost for hull 1,715, 

 7,500-ton tanker as built by the Fred T. Ley & Company, Mobile, Ala., is shown on 

 Fig. 43, Plate 11, no deduction being made for salvage value of materials. 



As yet none of the larger ships have been completely outfitted, and no figures 

 are now available as to the final total cost of this work. The partial figures now 

 on hand would indicate that the outfitting will cost, including material and labor, 

 about $600,000 for each 7,500-ton ship. The tankers will therefore cost in the 

 neighborhood of $1,250,000, or about $167 per D. W. T. This figure should be 



