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THe Marine REVIEW 194 ASTERN ot ei -4L 838 8 t -6 8 . AHEAD 2k 44 hs + & A ; 834 83s .6 1.0 22 was taken advantage of to plot the forces in terms of the model resist- ance. This model resistance is that of the model when towed indepen- dently. The effect of the side suction upon resistance was not measured. Figs. 2, 3, 4 and 5 show the results obtained. Fig. 2 shows the pulls and repulsions upon model. 834 as _ it passes model 838. It also shows, for the position abreast, the reactions up- on both models 834 and 838 for three spacings. Fig. 3 refers to models 858 and 866, showing the forces act- ing upon 858 as it passes 866. It also shows for the abreast position the model reactions for three spac- ings and the actions upon model 858 for greater distances apart. Fig. 4 shows curves of the pulls and repul- sions upon model 834, corresponding to Fig. 2, and Fig. 5 shows the same for model 858, corresponding to Fig. 3. In Figs. 4 and 5, the zero posi- tion means that the centers of the two models are abreast' one another. Their center lines were 3.9 ft. apart which was maintained throughout. The position two-tenths ahead means that the center of model 834 is two-tenths of its length forward more erratic. of the center of model 838, while in the position five-tenths ahead, the center of model 834 is abreast the bow of model 838, while in the position five- tenths astern, the center of 834 is abreast the stern of 838. It will be ob- served that models 834 and 838 were very similar, the main difference be- ing that one had a finer midship sec-. tion than the other but both of them were of the fine type. Models 858 and 866 were similar in coefficients, etc., but 858 was broad and shallow while 866 was narrow and deep. The results obtained from the fine models were somewhat more consist- ent than those obtained from the full models, the latter being apparently Broadly speaking, how- ever, the results are in general accord and appear tto indicate that when one vessel overtakes another on a paral- lel line, quite close to the latter, the sequence of phenomena is about as follows: When the overtaking vessel just begins to overlap the other, there is little force acting. There appears to be a repulsion at 'both bow and stern and curiously enough the repelling force wpon the stern appears to be 2.1 22 19 L APART oe 1.0 1.0 -24L APART. oe T aC 128 lL AFART. FORCES UPON MODEL 834 WHEN PASS- ING MODEL 838. THE ARROWS SHOW THE DIRECTIONS OF THE FORWARD AND AFTER FORCES. THE FIGURES SHOW THE AMOUNTS EXPRESSED AS FRACTIONS. OF THE TOTAL RESISTANCE. SPEED OF MODELS 2TOSKNOTS Fia.2. greater than that upon the bow. The resulting tendency is for the over- taking vessel to turn in toward the overtaken vessel. When partially overlapping, the tendency as in the 0.6-E> position in. Figs. 2..and 3 is for the bow to be drawn in while the stern is still repelled. In this con- nection Fig. 1 is of interest, as it indicates that the natural position as- sumed by the torpedo boat destroyers with the stern canted out and the bow drawn in, agrees with the ten- dencies shown in Figs. 2 and 3 for the 0.6-L position. 'As the overtaking vessel continues to pull up, the suction at the bow becomes stronger and the repulsion of the stern falls off, until, as they come abreast, there is a rapid change in the stern force, which shifts from repulsion to strong suction. As the overtaking vessel draws ahead, there is a reversal of condi- tions, the bow pull falling off rapidly and soon becoming a repulsion, while the stern pull 'becomes stronger, reaching its maximum when the cen- ter of the overtaking vessel is about two-tenths its length ahead the cen- ter of the overtaken vessl. It should