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Full Form Is an Economic Loss Maximum Block Coefficients and the Economic Disadvantage of Full Form Analyzed—Larger Capacity Offset by Greater Cost Per Mile PAPER on Block Coefficients A of Cargo Vessels was read by the present writer at the summer meeting of the Institution of Naval Architects held in Paris in 1922, and a method of arriving at these coefficients was given. The coefficient values were based on available and published records of the results .of model experiments, and are intended to be applied to vessels having midship-section coeffi- cients within the limits of 0.96 to 0.99 and length between 350 feet and 550 feet and having — values VL from 0.50 to 0.70. Model experiment records appli- cable to cargo vessels were collected, and the results plotted in the form of Froude’s C value curves on a K basis. A note was taken in each case of the K value where the first definite steepening of the C curve oc- cured, because this denoted an excess increase in resistance displacement ratio and consequent loss in propul- sive economy. This first steepening was found to occur frequently in the vicinity of a C value of 0.70 for vessels of good form and about 400 feet length, and it may almost be said that the proposed block coeffici- A paper entitled “(Maximum Block Coefficient and the Economic Disadvantage of Full Form” presented Nov. 11, 1926 at the meeting of the Society of Naval Architects and Marine En- gineers at New York. The author, W. J. Lovett, is attached to the well known British shipbuilding firm, Workman, Clark & Co., Ltd. BY W. J. LOVETT if associated with good tank have a C value of 0.70 at ents, form, the designed speed. A smaller C value in power and consequent reduction Are Lake Cargo Vessels Too Full in Form? The economic disadvantage of full form is discussed in the ac- companying paper which was read before the Society of Naval Archi- tects and Marine Engineers at their last annual meeting. An article by Edwin B. Sadtler, point- ing out the disadvantages of too full a form in the case of a specific type of Great Lakes freighter, appeared on page 71 of the November number of MARINE REVIEW. Admiral Taylor in his presi- dential address before the Society of Naval Architects and Marine Engineers said: “I venture to call the attention of our Great Lakes members to the fact that a large 15-knot overseas cargo vessel is nearly twice as speedy as a large 9-mile lake cargo carrier. We all know that on the lakes extra- ordinary and successful, and may I add, expensive efforts have been made to save the time spent in port by cargo carriers. Short as the lake trips are it may be that the time has come to save time under way.” will be attained if a finer block coeffi- cient is adopted, and the values here given may be taken as maximum fullness of form for economic propul- TABLE I—BLOCK COEFFICIENTS LENGTH — BREADTH sion. From records in the press and from correspondence it would appear that this method of determining suit- able block coefficients has come into fairly . general use, and the values as then proposed are given in Table 1 but including also a_ speculative development for values at the high- er speeds, so that the whole table has not hitherto been published. The values in Table 1 are suitable for smooth water service, but cases might occur in which a finer modelled vessel would show a financial gain over the year’s trading, and this has been demonstrated in the case of two similar vessels recently buillt. vessel »“‘A” has ordinary fullness as determined from Table 1. Vessel “B” has the same machinery as “A,” but, because it has a finer coefficient, it was possible to increase the displace- ment and it was found that 500 tons could be added without increase of _ power or consumption at 9 knots speed, and at 10 knots a very slight reduction in power was indicated for the larger, finer vessel. The speeds were then forced up to 11 knots, and a distinct and clearly defined reduc- tion in power was again apparent. The general particulars of both vessels are given in Table 2 and the comparative powers and consump- tions in Table 8. (on page 50) In Mr. J. Semple’s paper on “Some Experiments on Full Cargo Ship Models” read before the Institution (Continued on Page 50)