474 HYDRODYNAMICS IN SHIP DESIGN Sec. 66.10 



allowances such as doubling the estimated this size, also at the time of writing, should be 



appendage resistance. able to produce full power at a fuel rate of 0.58 



Further, it is assumed in all the foregoing that lb per horse per hr; certainly on 0.6 lb [Barnaby, 



the resistance of the final ABC hull will not K. C, INA, 1950, p. J8]. An estimated allowance 



exceed that of the Taylor Standard Series hull for the hotel load, for full atmosphere control, 



of the same proportions and weight displacement, including dehumidification, and for other items 



This is certainly the end to be sought; in fact, not covered by the hydrodynamic specifications, 



the designer should look forward to bettering the is 0.1 lb per horse per hr, making a total of 0.70 



TSS performance. In this connection the following lb for all purposes. 



is quoted from a discussion by S. A. Vincent As a check on the first item, W. I. H. Budd and 



[SNAME, 1948, p. 403], where the comments in 0. Praznik show a fuel rate of slightly under 



parentheses are those of the present author: 0.575 lb of oil per horse per hour for all purposes 



". . . few vessels having prismatic coefficients from about tSNAME, 1948, Fig. 1, p. 472]. This apparently 



9.72 to 0.75 are as good as the (Taylor) Standard Series does not mclude fuel for the hotel services, 



models at designed speeds suitable for the prismatic Concerning the second item it is probably more 



coefficient (see Fig. 66.A). At higher or lower speeds for logical to determine the fuel rate for services on 



this particular range of vessels and also for vessels having ^ ^^^^^ ^f ^j^^ ^^^^^ personnel on board per day at 



prismatic coefficients beyond this range, the resistance for . , tt , i , ■ 



good forms is below that of the Standard Series, often ^ea or in port. However, as the rates in question 



considerably below . . . the designer would do well to are bemg used solely for a design example rather 



have the Standard Series form in mind when drawing than for an actual ship they need not be more 



the lines of vessels having prismatic coefficients between than roughly representative of good practice at 



about 0.72 and 0.75." ^ ^^e time of writing. 



- ,, i i. J. XI. i_ 11 1. J 1 J r The fuel consumption per voyage is then 



In the event that the hull shape developed for ^. ^j c^t^r^,^^c^n,^\,r^nn\ o To-, i • 



^, ,„^ , . , ,, ^ . ^c , ^, estimated as 290(16,930) (0.70) = 3,437 kips or 



the ABC ship should prove more resistful than . ro^ ^ j. a j n ■ -, rm ^ mi_- • ^r/^ ^ 



^, „ , o/ J J ci • -i • -ui J. 1 1,534.4 t. A round figure is 1,550 t. This is 650 t 



the Taylor fetandard Series, it is possible to apply , ,, ^i ^^ „ , j. ' ,, r- , . ,, 



. , T i i. ■ 1 XI- less than that allowed tor in the nrst weight 



a contra-guide ending to the single centerline ^. ^ , __„ ^ ^, , ^ 



, ,° . jj mu X ii. estimate, and 200 t more than enough to com- 



skeg, and to use a contra rudder. Ihese together '. ^, ..„ , . ,,.,. , „. 



, , , . , . ^ e IX- pensate tor the 450 t of additional propellmg- 



should regain a certain amount of power lost in , . - i , - ,i i ,- , 



, . . ,1 1 „ .X li- Ax xi ■ X -x machinery weight m the second estimate, 



driving the hull itself. At this stage it appears » /. ,, , , ,- ^ i „ i 



,,,,,,, ■ ,. , , iz-irr A further check on proportions of hull-and- 



that a bulb bow might be benehcial. It so, a „^^. • , x x x . T • i . -,1 i, r i 



,.,, , ^. ,,, ., nttings weights to total weight with all useful 



still greater amount of power could be regained. , , , i , - r ■ , ^ , , i i 



^^,« r. jT^x- X iiT^- • i-tT7-t.x load, on the basis of riveted seams and welded 



66.10 Second Estimate of Principal Weights. , ^/ • xi. i. n i x- xu x x 



„, , , . .,x-x -xLx^x butts in the shell plating, a three-compartment 



The most uncertain weight items in the farst ^ , , , „ i i -i-, xi -i i i- 



, , . , . „ „„ . ^, J- XI- 1- 11 standard tor floodability, the possible use oi a 



rough estimate of Sec. 66.4 were those of the hull, . . ^ ... , ,,, 



,, ,,. , . 1 xi i- 1 T special type of smgle-screw stern, and the 



the propelhng machinery, and the fuel. In . ,. . ^ ,- i , „ ^ . -i - i , 



, -Ti xi 1 • r CI ^rv r, XL judicious use of hght alloys for topside weights, 



accordance with the conclusions of Sec. 69.2 the ... ^ ,, x .i T n -,i ^,,- i ii 



. _ „ , . ■ , , 1 1 xt 1 - r indicates that the hull proper with nttings should 



ABC design is to be worked up on the basis of a ■ . . x or x r xi i i i i • mi 



. 1 11 weigh about 35 per cent of the loaded ship. The 



—,, , , •, 1 1 • /. X- X xi- X- r original hull weight of 6,400 t may be reduced at 



The best available information, at the time of ,, .° , , , - r,^V^ . mi • - i 



/,r.rr^ r I . • 1 i this stage to about 5,960 t. Ihe original margin 



writing (1955), for a complete single-screw steam . ._„ 7 • x i o . /• i i 



, ^ .',, J. ,„„„rv X -i-T r,r.r. ot 500 t, lust uudcr 3 per cent, may safely be 



power plant in the range of 16,000 to 17,000 ^ ^ oor^ x ■ x u x o x 



; ..,„.,, , mi X X 1 X- x 1 cut to 330 t, just about 2 per cent, 



horses is 165 lb per horse, ihe total estimated , ■ ■ i , ,• , , , , , c „ 



„. 1 , . 1, , ji • X • .1 A second weight estimate looks about as follows: 

 propelling-plant weight at this stage is then 



16,930(165) = 2,793.5 kips or 1,247.1 t; say 1,250 (a) Liquid bulk cargo 4,000 t 



t. This is 450 t, or 56.3 per cent more than the (b) Package cargo 3,000 t 



800 t of the original estimate, an indication of (c) Hull and fittings 5,960 t 



the surprises that often turn up in operations of (d) Propelling machinery 1,250 t 



this kind. (e) Fuel, including reserve 1,550 t 



From Table 66. c in Sec. 66.2 the estimated (f) Fresh water, supphes, and the like . 400 t 



fuel to be burned per voyage corresponds to that (g) Weight margin 330 t 



for approximately 290 hours of steady steaming 



at maximum designed power. A steam plant of Estimated total weight displacement 16,490 t 



