UNIVERSITY OF CALIFORNIA PUBLICATIONS COLLEGE OF AGRICULTURE AGRICULTURAL EXPERIMENT STATION BERKELEY, CALIFORNIA THE RELATIVE COST OF YARDING SMALL AND LARGE TIMBER BY DONALD BRUCE BULLETIN No. 371 October, 1923 UNIVERSITY OF CALIFORNIA PRESS BERKELEY 1923 Digitized by the Internet Archive in 2012 with funding from University of California, Davis Libraries http://www.archive.org/details/relativecostofya371bruc THE RELATIVE COST OF YARDING SMALL AND LARGE TIMBER By DONALD BEUCE In an investigation of the relative cost of making logs from small and large timber (described in a previous bulletin 1 of this series), it was shown that it costs three times as much per m.b.m. to make logs from 18 -inch as from 48 -inch trees, and that below that diameter the costs undoubtedly rise rapidly with each further decrease in size. In *6 a-CL Stut tvA V b-b 3ru< iy£ V c-c JtUi tyC \ ^ V H V \ c Q 16 20 ZZ Z4 Z6 28 30 32 34- 36 38 40 4Z Tree, d/ameter breast ■ hiqh — inches 44 46 48 Fig. 1. — Influence of tree diameter on cost per M.B.M. of yarding in three localities, showing relatively high cost for small trees. the following pages are given the results of similar studies of the cost of yarding with steam donkey engines. These investigations included the detailed timing by stop watch of the handling of every log on two complete settings and on an additional half setting. Although two of these three studies were located in conditions representative of the east side of the Sierra and the other in those typical of the west side, and although the organization of the yarding crew and its equipment were similar in no two instances, yet in all three studies it was found that it costs from five to eight times as much per m.b.m to yard logs from 18-inch as those from 48-inch trees and that for trees below 18 inches in diameter costs are undoubtedly even higher. i Bruce, Donald, "The Relative Cost of Making Logs from Small and Large Timber," Bulletin 339, University of California Agricultural Experiment Station, January, 1922. 4 UNIVERSITY OF CALIFORNIA— EXPERIMENT STATION Table 1 and figure 1 summarize these results. The similarity in form of the three curves in the figure is striking; and the ratios between the highest and lowest of each of the three sets of values as shown in the table differ little. Tn Study A, the 18-inch trees cost 7.8 times as much per m.b.m. to yard as did the 48-inch trees, in TABLE 1 Influence of Tree Diameter on Cost of Yarding Labor Diam- Cost per M. B. M., G ross Scale breast Study B Study C high, Study A Average inches Yarder Swing Total Yarder Swing Total 18 $5.38 $4.27 $1.55 $5.82 $3.38 $1.88 $5.26 $5.49 20 3.16 2.45 .94 3.39 2.65 1.45 4.10 3.55 22 2.09 1.69 .69 2.38 2.01 1.17 3.18 2.55 24 1.69 1.25 .55 1.80 1.56 .92 2.48 1.99 26 1.36 1.00 .46 1.46 1.27 .78 2.05 1.62 28 1.15 .85 .41 1.26 1.09 .68 1.77 1.39 30 1.04 .75 .37 1.12 .98 .61 1.59 1.25 32 .97 .69 .34 1.03 .91 .56 1.47 1.16 34 .92 .64 .33 .97 .85 .54 1.39 1.09 36 .86 .62 .31 .93 .81 .50 1.31 1.03 38 .83 .60 .30 .90 .78 .48 1.26 1.00 40 .78 .59 .29 .88 .75 .47 1.22 .96 42 .76 .58 .28 .86 .71 .46 1.17 .93 44 .72 .57 .27 .84 .68 .45 1.13 .90 46 .70 .56 .27 .83 .65 .44 1.09 .87 48 .69 .55 .26 .81 .62 .44 1.06 .85 Wage scale used: Per hour Hooktender : $.85 Engineer 67% Fireman 47% Woodbuck 45 Rigger, head .60 Rigger, assistant, chaser, frogger, chute tender 55 Unhooker 55 Choker hole digger, frog shoveler 45 Whistle punk 40 Teamster 55 Horse 25 Crew cost per minute: Study A, $.11.5; Study B, yarder, $.109; swing, $.051; Study C, yarder, $.102; swing, $.067. Study B, 7.2, and in Study C, 5.0, with an average of 6.5 times as much. No figures were available for trees under 18 inches in diameter since trees smaller than this were seldom yarded, but the trend of the curves is convincing evidence that even higher costs would be encountered for these smaller sizes. It is to be noted, of course, that machinery, rigging, and crew organization were all designed to handle large timber and that no definite conclusions can be drawn from the present study applicable to stands consisting wholly, or Bulletin 371 J the relative cost of yarding timber 5 almost wholly, of very small trees and yarded with machinery appropriate thereto. The costs given are for labor only, without any allowance for depreciation, renewals, or maintenance of equipment. The inclusion of such items would, of course, increase all the costs, but there is no reason to suppose that it would affect materially the relations between the costs for trees of different sizes. The rapid fluctuations of wage scales during- the past few years have made cost figures in dollars and cents misleading. Throughout this study, therefore, all costs have been reckoned in minutes of time spent by the yarding crew, with the exception of table 1, in which time was translated into money at an assumed scale of wages (stated in the table) which is fairly representative of 1923 conditions. The data obtained in each study will now be described, with an explanation of how the conclusions have been reached. Each study will be treated separately, the first in order being outlined in con- siderable detail, while the others, similar in technique, will be more briefly summarized. All three studies were made in cooperation with representative lumber companies of the Sierra Nevada region under an agreement that the identity of the companies would not be disclosed. The studies will therefore be referred to as Study A, Study B, and Study C, respectively. STUDY A This study was located under conditions typical of the better portions of the east side of the Sierra. The topography was gentle (as shown in the map of figure 2), the ground sloping gradually away from the railroad track, thus offering an almost ideal yarding chance. The timber was about 80 per cent western yellow pine and Jeffrey pine ("California White Pine") and 20 per cent white fir. The stand per acre averaged about 44 m.b.m. 2 (on the area actually yarded), an unusually heavy stand for this region. The study covered a half setting only, or about 13.3 acres, the yarder remaining in one position (except for a slight shift on account of an interference of its line with the steam saw) throughout the period of observation. The yarder was a 10 by 11 simple-geared wide-drum machine manufactured by the Willamette Iron and Steel Works. The lead of the line was through a bull block hung near the ground. The logs were all hauled in long lengths and were bucked 2 This is by the Scribner log rule, which is used throughout this bulletin. 6 UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION into short lengths (averaging about 16 feet) by a steam saw in a short chute at the landing. Since only one engine was used, the spotting of the logs for the steam saw was done by the yarder. Logs were generally handled one at a time, although occasionally where it was particularly convenient to do so, two were taken at a single trip. The average load per trip was 116-1 feet b.m. The yarding of the area required nine working days. The location of the railroad, land- ing, bucking chute, yarder, and the various positions of the main line are shown in figure 2. Fig. 2. — Contour map of yarding area of Study A, showing (A) railroad, (B) landing, (C) bucking chute, (D) position of yarder, and the positions of the yarding line. The crew employed was as follows : 1 hooktender 1 engineer 1 fireman 1 wood buck 3 risers 1 chaser 1 frogger 1 chute tender 1 choker hole digger 1 whistle punk In addition a horse was used for changing line, the yarder not being equipped with a straw line. The fuel burned by the donkey consisted of mill refuse, the value of which was not included in the operating cost. BULLETIN 371] TH E RELATIVE COST OF YARDING TIMBER Description of Data Collected The data collected consisted of stop watch observations of each trip made by the yarder and a measurement and scale of the logs yarded. This information was obtained by two observers, one stationed at the landing and the other near the outer end of the yarding line. The stop watches used were graduated in minutes and hundredths of minutes to facilitate computations. The subdivisions of time recorded were as follows: ' ' Out ' ' : The return of the main line to the position of the log next to be hauled. "Shift": Movements of the main line (after the "out") for the explicit purpose of leaving a choker at a desired point. " Shifts" were often avoided by carrying the chokers by hand from the end position of the out. "Taking off choker" : "Removal of empty choker in connection with a " shift" — usually occurring between the "out" and the "shift." "Hook": Connecting the choker to the line, measured from the end of the "out" or "shift" until the line was under tension for the trip in. " In " : The hauling of the log to the landing, measured from the end of the "hook" until the engine stops. This item was usually divided into two or more parts by the "block." "Block": Unhooking the choker, passing it around the bull block and hooking it to the line again ; measured from the time the engine stopped until the line was once more under tension, but with minor engine movements to assist in this operation included therein. "Spotting": Engine movements for the purpose of placing logs in the chute in convenient position for bucking into short lengths. "Unhook": The release of the choker from the log or sometimes of the choker from the line and the placing of an empty choker or chokers on the line; measured from the end of the "in" to the beginning of the "out." "Delays": The cause of each delay was identified and noted. Delay items were later grouped into those essentially connected with the ' ' out ' ' (hereafter called ' ' out delays " ) , the " in, " etc., and those which cannot be thus associated with any of the above items and hence must be classed as "general delays." For example : the hanging up of a log on a stump is an " in delay ' ' ; the loss of a choker from the line during the "out" is an "out delay," while the time occupied in changing the positions of the lines or repairing the blocks is ' ' general delay. ' ' 8 UNIVERSITY OF CALIFORNIA— EXPERIMENT STATION Table 2 is a summary of the results obtained and shows for each of the above items the average time per trip, the per cent of the total time, and the average time per occurrence. TABLE 2 Distribution of Time between Operations Involved in Yarding STUDY A Operation Out inside of bull block Out outside of bull block Total out Shift Taking off choker Hook Total time between out and in In outside of bull block In inside of bull block Total in Block. Spotting Unhook Total time between in and out Delays — Out Choker dropped Choker fouled in bull block Miscellaneous Delays — In Hung up on stumps, trees, logs and slash Avoiding stumps, trees, logs and slash Chute trouble Miscellaneous : Delays — Spotting Waiting for steam saw Delays — General Changing line Stopping early at noon or night Engine trouble Repairing lines, blocks, etc Shifting donkey engine Miscellaneous Total delays Total time per trip Average time per trip — minutes .29 .72 .16 .27 .57 1.23 .53 .93 1.19 .81 .06 .02 .05 .61 .22 .33 .31 .27 .64 .17 .09 .11 .08 .27 1.01 1.00 1.76 .93 2.00 3.23 9.93 Per cent of total time 2.9 7.3 1.6 2.7 5.8 12.4 5.3 9.4 12.0 8.1 0.6 0.2 0.5 6.2 2.2 3.3 3.1 2.7 10.2 10.1 17.7 9.4 20.1 32.5 100.0 Average time per occurrence — minutes .29 .72 .21 .36 .55 .79 .53 .32 .60 .25 .81 .54 .56 1.95 1.09 1.50 1.59 12.30 6.34 4.03 4.93 40.13 The reason for this last column is that a number of items occurred but rarely, instead of regularly once per trip (for example, changing the position of the line), and that it is of interest to know not only what proportion of the entire time cost may be attributed to such an item but also the average time required therefor when it occurred. Bulletin 371] TH e relative COST of yarding timber Influence on Time of Variations in Distance which Log is Hauled Since the size of the log which was hauled during each trip of the line was recorded, it would have been a simple matter to obtain the average time required in the case of logs of various sizes for each of the above items and for the trip as a whole. The resulting figures might not reflect accurately, however, the influence of log size on time and hence on cost, because there is a possibility that variations in the distances hauled might have distorted their interrelations. It is not improbable, particularly in view of the patchy distribution of the stand, that the large logs may have been hauled on the average a shorter distance than the small, or vice versa. It is therefore neces- sary to determine first the influence of variations in distance on the several time factors so that for such variations suitable allowances can be made. This analysis can be simplified by segregating the various time items into three groups : ( 1 ) those which vary with distance ; ( 2 ) those which are independent of distance and which, while variable on account of accidental causes, may be treated as a constant in the average trip; (3) those which constitute a ''time overhead" properly to be pro-rated against the total of the first two groups. In the first group fall the following : "Out" outside of bull block 72 minutes per trip "In" outside of bull block 1.23 minutes per trip "Out delays" outside of bull block 11 minutes per trip "In delays" outside of bull block 1.05 minutes per trip Total of items varying with distance 3.11 minutes per trip In the second group fall the following : "Out" inside of bull block 29 minutes per trip "Shift" 16 minutes per trip "Taking off choker" 27 minutes per trip "Hook" 57 minutes per trip "In" inside of bull block 53 minutes per trip "Block" 93 minutes per trip "Spotting" 1.19 minutes per trip "Unhook" .81 minutes per trip "Out delays" occurring inside of bull block 02 miuutes per trip "In delays" occurring inside of bull block 42 minutes per trip "Spotting delays" 27 minutes per trip Total of items independent of distance 5.46 minutes per trip In the third class fall the "general delays" amounting to 1.36 minutes per trip. 10 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION To analyze the four items in the first of these groups, the trips were segregated into distance classes and the average "in," "out," "in delay," and "out delay" for each distance was obtained. The results, as adjusted graphically by means of curves to give regular progressions in the values, are shown in table 3. The decrease of the "out delay" time as the distance increases is probably purely accidental, for in the other two studies the trend is in the opposite sense. The other items and the total, all increase as would be expected, TABLE 3 Influence of Variations in Distance on Yarding Items Directly Affected Thereby STUDY A Time per trip, minutes "Diet onnp lylolallUU) feet "Out" "Out delay" "In" "In delay" Total 50 .14 .37 .21 .18 .90 100 .24 .30 .39 .34 1.28 150 .32 .25 .54 .48 1.59 200 .39 .21 .66 .58 1.84 250 .44 .18 .75 .66 2.03 300 .50 .15 .83 .73 2.21 350 .55 .13 .91 .81 2.40 400 .61 .11 1.00 .88 2.60 450 .66 .10 1.08 .96 2.80 500 .71 .09 1.18 1.04 3.02 550 .76 .09 1.28 1.14 3.27 600 .82 .08 1.40 1.24 3.54 650 .87' .08 1.52 1.34 3.81 700 .94 .07 1.66 1.46 4.13 750 1.00 .07 1.82 1.60 4.49 800 1.07 .07 1.96 1.73 4.83 850 1.15 .06 2.14 1.89 5.24 900 1.24 .06 2.33 2.05 5.68 although not in the same proportion as the distance. Increasing the distance nine times increases the time less than five times. The average total time required for a trip of any given distance is the sum of that stated in table 3 plus the total of the items independent of distance, or 5.46 minutes (see page 9), plus the proper share of the "general delays." Since this latter item amounts to 1.36 minutes per trip out of a total of 9.93 minutes, it constitutes 15.9 per cent of 1 ^fi the sum of the items other than general delays : *' — — — = .159 o.Jo l.OO This percentage may accordingly be used as a pro-rating coefficient to distribute the "general delay" item. These computations and the resulting total time per trip are given in table 4. BULLETIN 371] TH E RELATIVE COST OF YARDING TIMBER 11 Influence on Time of Variations in Size of Log It is now possible to investigate the influence of log size on cost. The most practicable measure of log size is the gross scale, since any defective portions of a log will weigh nearly as much as though they were sound. The available trips were therefore re-classified by the gross volume hauled, each class comprising a range of 100 feet b.m. TABLE 4 Influence of Variations in Distance on Total Time of Yarding per Trip STUDY A Time per trip, minutes A B A+B 1.159x(A+B) Distance Time of items Average time of Sum of all items Total yarded, directly items except including feet affected independent of general general by distance distance delays delays 50 .90 5.46 6.36 7.37 100 1.28 5.46 6.74 7.81 150 1.59 5.46 7.05 8.17 200 1.84 5.46 7.30 8.45 250 2.03 5.46 7.49 8.68 300 2.22 5.46 7.68 8.89 350 2.40 5.46 7.86 9.11 400 2.60 5.46 8.06 9.35 450 2.80 5.46 8.26 9.57 500 3.02 5.46 8.48 9.83 550 3.27 5.46 8.73 10.12 600 3.55 5.46 9.01 10.43 650 3.81 5.46 9.27 10.74 700 4.13 5.46 9.59 11.11 750 4.50 5.46 9.96 11.54 800 4.83 5.46 10.29 11.92 850 5.24 5.46 10.70 12.39 900 5.68 5.46 11.14 12.91 It is obvious that many items, such as "out" and "out delays," will be entirely independent of the load hauled. There are in fact but five which are correlated therewith, i.e., "in outside of the bull block, "in delays" outside of the bull block, "hook," "in" inside of the bull block, and "in delays" inside of the bull block. The first two of these are items affected by the distance hauled, while the remaining three are not. The latter can therefore be analyzed directly by computing the average time of each for the various size classes and graphically readjusting the averages by means of curves. The resulting values are given in the last three columns of table 5. In the case of the former items, however, the values must be dis- counted for the actual average distances hauled. This has been done 12 UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION by entering in the second and third columns of the same table the average percentage ratio between the actual time for each log in a given size class and the average time for the corresponding distance. To find the average "in" time for a log of given size hauled a given TABLE 5 Influence of Variations in Size of Log on Yarding Times Affected Thereby STUDY A Volume of log, gross scale, Scribner, feet, b.m. "In" (outside of bull block), per cent of average time for corresponding distance "In delay" outside of bull block, per cent of average time for corresponding distance "Hook," minutes "In" inside of bull block, minutes "In delay" inside of bull block, minutes 100 86.5 38. .50 .42 .19 200 89.0 40. .51 .42 .20 300 90.8 42. .51 .43 .22 400 92.5 44. .51 .44 .23 500 94.0 46. .51 .44 .25 600 96.0 48. .52 .45 .26 700 97.0 52. .52 .46 .27 800 98.5 56. .52 .46 .28 900 99.7 60. .53 .47 .30 1000 100.8 66. .53 .48 .31 1100 101.5 72. .54 .49 .33 1200 102.7 78. .54 .49 .34 1300 103.5 88. .55 .50 .35 1400 104.0 98. .56 .51 .37 1500 104.6 108. .56 .51 .38 1600 105.2 122. .57 .52 .40 1700 105.9 136. .58 .53 .41 1800 106.3 152. .59 .53 .42 1900 107.0 168. .60 .54 .44 2000 107.3 184. .61 .55 .47 2100 107.6 204. .62 .55 .52 2200 108.0 218. .64 .56 .57 2300 108.3 236. .66 .57 .66 2400 108.5 250. .68 .58 .75 2500 108.8 264. .70 .58 .83 2600 109.0 278. .72 .59 .92 2700 109.2 290. .74 .60 1.01 2800 109.5 298. .76 .60 1.09 2900 109.8 306. .78 .61 1.18 3000 110.0 316. .81 .62 1.27 distance, it would then be necessary to select from column 4 of table 3 the "in" time corresponding to the distance and multiply it by the percentage correction from column 2 of table 5 corresponding to the size class. The effect of log size on the items listed in this table is remark- ably small. Only the two delay items are at all sensitive to variations Bulletin 371] the relative COST OF yarding timber 13 therein. Large logs cost more to handle than small, but the increase in cost is far from proportionate to the increase in volume. It is obvious that since log size affects differently the several details that go to make up yarding time, its effect on the total yarding time will TABLE 6 Influence of Variations in Size of Log on Total Yarding Time per Trip for Different Distances STUDY A Volume of log, gross scale, Total time of trip, Time cost .per M.B.M., gross, minutes minutes Distance in feet Distance in feet Scribner, feet, b.m. 100 500 900 100 500 900 100 7.02 8.43 10.61 70.2 83.4 106.1 200 7.07 8.51 10.75 35.3 42.5 53.7 300 7.12 8.59 10.87 23.7 28.6 36.2 400 7.16 8.66 10.99 17.9 21.4 27.5 500 7.20 8.73 11.10 14.4 17.5 22.2 600 7.25 8.81 11.23 12.1 14.7 18.7 700 7.30 8.90 11.39 10.4 12.7 16.3 800 7.35 8.99 11.55 9.2 11.2 14.4 900 7.40 9.09 11.70 8.2 10.1 13.0 1000 7.46 9.21 11.91 7.5 9.2 11.9 1100 7.51 9.32 12.10 6.8 8.6 11.0 1200 7.57 9.44 12.30 6.3 7.9 10.2 1300 7.65 9.60 12.59 5.9 7.4 9.7 1400 7.72 9.77 12.88 5.5 7.0 9.2 1500 7.80 9.92 13.16 5.2 6.6 8.8 1600 7.88 10.13 13.54 4.9 6.3 8.5 1700 7.98 10.35 13.92 4.7 6.1 8.2 1800 8.08 10.58 14.35 4.5 5.9 8.0 1900 8.18 10.82 14.79 4.3 5.7 7.8 2000 8.30 11.07 15.20 4.1 5.5 7.6 2100 8.47 11.40 15.81 4.0 5.4 7.5 2200 8.61 11.66 16.24 3.9 5.3 7.4 2300 8.82 12.02 16.81 3.8 5.2 7.3 2400 9.00 12.32 17.28 3.7 5.1 7.2 2500 9.19 12.61 17.75 3.7 5.0 7.1 2600 9.38 12.93 18.22 3.6 5.0 7.0 2700 9.56 13.21 18.64 3.5 4.9 6.9 2800 9.73 13.44 18.97 3.5 4.8 6.8 2900 9.90 13.68 19.31 3.4 4.7 6.7 3000 9.98 13.95 19.69 3.3 4.6 6.6 depend somewhat on the distance hauled. Table 6 shows this effect for distances of 100, 500, and 900 feet respectively, which are the approximate minimum, average, and maximum distances hauled on the area studied. The following sample computation will illustrate the method of derivation of the table. 14 UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION For a 100-foot Log Hauled a Distance of 100 Feet "Out" outside of bull block. 24 minutes (table 3, column 2) "Out delay" outside bull block 30 minutes (table 3, column 3) "In" outside of bull block 34 minutes (table 3, column 4 and table 5, column 2 — .39 X .865) "In delay" outside of bull block 13 minutes (table 3, column 5 and table 5, column 3 — .34 X .38) "Hook" 50 minutes (table 5, column 4) "In" inside of bull block 42 minutes (table 5, column 5) "In delay" inside of bull block 19 minutes (table 5, column 6) All other items except general delays 3.94 minutes (page 8) Total 6.06 minutes "General delays" (15.8 per cent) 96 minutes Grand total 7.02 minutes The second, third, and fourth columns of the table give the values thus computed. The last three columns give the same values divided by the average volume of the class, or, in other words, the time per m.b.m. It will be observed: (1) the importance of distance is rela- tively greater in the case of large logs than in that of small; (2) the importance of log size is relatively greater for short distances than for long; (3) for all distances the very small logs are exorbitantly expensive to handle. Influence on Time of Variations in Size of Trees from which Logs are Made It now remains to correlate these facts with tree diameter instead of log diameter. To determine this relation requires a knowledge not only of the average gross volume of trees of various diameters, but also of how each size was subdivided into logs for yarding. Both of these facts were given in the previous study already referred to, 3 and they are therefore merely recapitulated in the second column of table 7. A single figure opposite a diameter class indicates that trees of this size were yarded as a single log; two figures indicate that two logs were made thereof, and so on. The third column of this table is taken from column 3 of table 6 (interpolated). In this, however, "spot" and "spot delays" are treated as constants, which is hardly justifiable in computations based on the tree as the unit. The only feasible method of readjust- ing this item of time seems to be to assume that the "spot" and "spot delay" times should be distributed in the same proportions as the time spent by the steam saw in sawing trees of the same sizes. » Bulletin 339 of this series, page 330, table 14. Bulletin 371] THE rel a.tive COST OF YARDING TIMBER 15 TABLE 7 Influence of Variations in Tree Diameter on Time of Yarding a Distance of 500 Feet STUDY A "Spot" and Total "spot time all Tree Same, delay" items diam- Gross less 1.46 corrected including eter scale Time- for "spot" Time to be revised Total breast of logs — cost all and "spot for steam propor- "spot" time per Same, high, Scribner, items, delay," sawing, tional and "spot M.B.M., curved, inches M.B.M. minutes minutes minutes to steam sawing, minutes delay," minutes minutes minutes 18 .161 8.48 7.02 5.0 .53 7.55 46.8 46.8 20 .279 8.57 7.11 5.1 .54 7.65 27.4 27.5 22 .464 8.71 7.25 8.0 .85 8.10 17.4 18.2 24 .526 8.76 7.30 8.3 .88 8.18 15.6 14.7 26 .647 8.86 7.40 8.8 .94 8.34 12.9 11.8 28 1.009 9.21 7.75 12.7 1.35 9.10 9.0 10.0 30 1.150 9.37 7.91, 13.7 1.46 9.37 8.2 9.0 32 1.351 .503 9.76 8.73 8.30 14.7 1.57 9.87 7.3 8.4 34 1.425 9.78 15.59 16.5 1.76 17.35 9.0 1.928 18.51 8.0 .559 8.78 36 1.616 10.16 16.02 17.8 1.90 17.92 8.2 2.175 18.94 7.5 .640 8.85 38 1.792 10.55 16.48 19.3 2.05 18.53 7.6 2.432 19.40 7.2 .694 8.88 40 1.941 10.93 16.89 20.8 2.22 19.11 7.3 2.635 19.81 6.8 .789 8.98 42 2.119 11.43 17.49 22.7 2.42 19.91 6.8 2.908 20.41 6.6 2.094 11.36 44 1.723 11.41 19.85 30.0 3.20 23.05 6.0 3.817 22.77 6.3 .845 9.03 1.441 9.82 46 1.991 11.06 25.53 26.4 2.81 28.34 6.6 4.277 29.91 6.1 .917 9.10 1.586 10.05 48 2.149 11.52 26.29 28.9 3.08 29.37 6.3 4.652 30.67 6.0 16 UNIVERSITY OF CALIFORNIA— EXPERIMENT STATION Column 4 gives the results of deducting the constant "spot" and "spot delay" times, while column 5 gives the steam saw times, based on the table just referred to in Bulletin 339, which may be used in redistributing them. Column 6 gives the revised "spot" and "spol delay" times. At the average load, 1200 feet b.m., which results from a 30-inch tree, the average value of 1.46 minutes is adopted. 1 46 Since this is — — or .1065 times the steam saw time, the remaining J. O. I "spot" and "spot delay" times are calculated by multiplying the steam saw time of each size class by this figure. Column 7 is the sum of columns 5 and 6 ; column 8 is column 7 divided by column 2, with the decimal shifted to express results in m.b.m. The final column is a graphical readjustment of column 8. This final column indicates that for the average yarding distance it costs 7.8 times as much to yard 18-inch trees as 48-inch trees, a ratio which is unaffected by the translation of the figures into dollars and cents as was clone in table 1. STUDY B This study was located on an area similar to that of Study A. As illustrated by the map of figure 3, the topography was gentle and the yarding chance nearly ideal. The timber also was similar except that the stand was in this instance about 24 m.b.m. per acre, a more normal value for this region. The study covered a complete setting, or about 66 acres, the yarder changing its position to face in the opposite direction when about half of the area had been yarded. The yarder used was (like that in Study A) a 10 by 11 simple-geared wide-drum machine made by the Willamette Iron and Steel Works. The logs were handled in long lengths but were dropped by this engine at the bull block, where they were picked up by a swing donkey which hauled them the remaining 300 feet to the landing and spotted them for the steam saw. The swing engine was a 9% by 11 "Cracker jack" yarder made by the same company. This method of handling increased not only the equipment and crew but also the daily output as well, since the yarding engine was relieved of a considerable amount of work which would otherwise have been required of it. The use of two engines necessitated separate studies of their operations. The data collected were, however, essentially the same as before. Bulletin 371] TH E RELATIVE COST OF YARDING TIMBER 17 Fig. 3. — Contour map of yarding area of Study B, showing (A) railroad, (B) landing, (C) bucking chutes, (D) positions of yarder, (E) positions of swing, and the positions of the yarding line. As in Study A, most of the log's were handled singly. A few logs were, on account of their convenient position, hauled by the swirig donkey only. The operation required for its completion 19 working days for the yarder and 20 for the swing. The average load per trip was 1403 feet b.m. The crew emphn^ed was as follows : 18 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION Yarder 1 hooktender 3% riggers 4 1 engineer 1 chaser 1 fireman 1 frogger 1 wood buck 1 choker hole digger 1 whistle punk Swing 1 hooktender y 2 engineer fireman % wood buck E chute tender whistle punk e As in Study A the fuel burned was mill slabs, the value thereof not being included in the costs, and a horse was used in changing line. The subdivision of the average trip of yarder and swing into its time elements is given in tables 8 and 9 respectively, which correspond to table 2 of Study A. TABLE 8 Distribution of Time between Operations Involved in Yarding STUDY B Operation Average time of trip — minutes Per cent of total time Average time per occurrence — minutes Out Shift Taking off choker Hook ..... Total time between out and in. In .94 Block 7 Unhook Delays — Out Choker dropped Miscellaneous Delays — In Hung up on stumps, trees, logs and slash Avoiding stumps, trees, logs and slash Waiting for limbing Insufficient power and waiting for steam Miscellaneous Delays — General Changing line Waiting for swing Engine trouble Repairing lines, blocks, etc Miscellaneous Total delays .94 .29 .20 .86 1.35 1.17 1.17 .09 .09 .55 .55 .01 .02 .97 .13 .20 .27 .16 1.22 .52 .04 .37 .31 Total time per trip 4.22 8.12 11.4 3.5 2.4 10.3 14.0 1.1 6.6 .1 .2 11.7 1.6 2.4 3.2 1.9 14.7 6.3 .5 4.5 3.6 11.4 16.2 14.0 1.1 6.6 50.7 100.0 1 .95 .43 .28 .86 06 .88 .55 .85 .59 2.21 1.31 2.20 2.39 15.32 3.07 3.62 10.34 * A fourth rigger was employed on 6 out of 19 days. 5 One-third of the wood buck 's time was charged to the loader. 6 The whistle punk was laid off after the first 10 days. 7 Since logs were not passed around the inner bull block this item occurred only in trips where a second bull block was used. Bulletin 371] TH e relative cost of yarding timber 19 TABLE 9 Distribution of Time between Operations Involved in Swinging STUDY B Operation Average time per trip — minutes Per cent of total time Average time per occurrence — ■ minutes Out .47 .47 3.70 3.70 .67 .67 1.75 1.75 .75 .75 .01 .31 .12 .11 .05 .16 .18 .10 .10 .22 1.36 8.70 5.4 5.4 42.5 42.5 7.7 7.7 20.1 20.1 8.6 8.6 .1 3.6 1.4 1.3 .6 1.8 2.1 1.2 1.1 2.5 15.7 100.0 .47 Hook 8 3.70 In .67 Spot 1.75 Unhook .75 Delays — out — miscellaneous .32 Delays — in Chute trouble 1.80 Changing choker .94 Miscellaneous Delays — spot — steam saw trouble 5.46 Delays — general Waiting for cars 23.40 Waiting for yarder 70.68 Landing blocked 1.58 Repairing chute 114.69 Miscellaneous Total delays Total time per trip Influence on Time of Variations in Distance which Log is Hauled As in the previous study, these figures have been analyzed by first determining the effect on time of distance and then, with proper allowances for the variations from the average distance of the distance which individual logs had to be hauled, the effect on time of the load. Since the distance hauled by the swing was constant, the influence of varying distance required investigation in the case of the yarder only. Table 10 gives information similar to that of tables 3 and 4 of Study A combined. The first five columns are parallel to the similar columns of table 3, while computations like those of table 4 are indicated by columns 6, 7, and 8. The constant items independent of distance in the present instance are: "Hook" 86 minutes per trip "Shift".... .29 minutes per trip "Taking off choker" 20 minutes per trip "Block" 09 minutes per trip "Unhook" 55 minutes per trip Total 1.99 minutes per trip s This operation was constantly delayed by work of yarder. 20 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION The general delays amount to 29.6 per cent of the total time and the 296 pro-rating coefficient is therefore „ „ n ' n ' — nn „ = .420, the value used in computing the final column. 1.000 — .296 TABLE 10 Influence of Variations in Distance on Total Time of Yarding per Trip STUDY B Time per trip — minutes Total Distance including yarded, Items Total, 42.0 feet "Out" "Out "In" "In independent exclusive of per cent for delay" delay" of distance general delays general delays 50 .12 .02 .13 .20 1.99 2.46 3.47 100 .21 .02 .24 .36 1.99 2.82 4.01 150 .31 .02 .36 .53 1.99 3.21 4.55 200 .40 .02 .47 .70 1.99 3.58 5.08 250 .50 .02 .58 .86 1.99 3.95 5.60 300 .59 .03 .69 1.03 1.99 4.33 6.12 350 .67 .03 .80 1.18 1.99 4.67 6.61 400 .76 .03 .91 1.35 1.99 5.04 7.14 450 .85 .03 1.01 1.50 1.99 5.38 7.62 500 .93 .03 1.12 1.66 1.99 5.73 8.11 550 1.00 .03 1.23 1.82 1.99 6.07 8.61 600 1.07 .03 . 1.33 1.96 1.99 6.38 9.06 650 1.16 .03 1.43 2.11 1.99 6.72 9.54 700 1.24 .03 1.53 2.27 1.99 7.06 10.02 750 1.31 .03 1.63 2.41 1.99 7.37 10.46 800 1.37 .03 1.72 2.55 1.99 7.68 10.92 850 1.44 .03 1.83 2.70 1.99 7.99 11.36 900 1.50 .03 1.92 2.84 1.99 8.28 11.79 950 1.55 .03 2.01 2.97 1.99 8.59 12.21 1000 1.60 .03 2.10 3.11 1.99 8.89 12.62 1050 1.64 .03 2.19 3.25 1.99 9.17 13.02 1100 1.68 .03 2.28 3.38 1.99 9.44 13.41 1150 1.72 .03 2.37 3.51 1.99 9.72 13.80 1200 1.75 .03 2.46 3.63 1.99 9.96 14.18 Effect on Time of Variations in Size of Log Table 11 shows the influence of the size of log hauled on the items that are affected thereby, that is, the ' Vin, " "in delay, ' ' and ' ' hook. ' ' This corresponds to table 5 of Study A. Table 12 corresponds to table 6 and shows the effect of log volume hauled on the complete yarding time per trip for different distances. Since the maximum yarding distance in the second study was slightly greater, columns for 1100 feet are included in this table in addition to those for 100, 500, and 900 feet. It will be observed that the con- clusions of the first study (page 14) are equally justified for Study B. Bulletin 371] TH E RELATIVE COST OF YARDING TIMBER 21 TABLE 11 INFLUENCE OF VARIATIONS IN SIZE OF LOG ON YARDING TIMES AFFECTED THEREBY' STUDY B Volume of log, gross scale, Scribner, feet, b.m. "In," per cent of average time for corresponding distances "In delay," per cent of average time for corresponding distances "Hook," minutes 100 93.8 31 .79 200 93.9 32 .79 300 94.0 33 .79 400 94.1 35 .79 500 94.2 37 .80 600 94.3 40 .80 700 94.4 43 .80 800 94.6 47 .80 900 95.0 51 .81 1000 95.4 55 .81 1100 95.8 59 .81 1200 96.3 65 .81 1300 96.8 71 .82 1400 97.3 77 .82 1500 97.8 84 .83 1600 98.7 91 .83 1700 99.7 99 .84 1800 100.7 107 .84 1900 101.7 116 .85 2000 103.1 126 .87 2100 104.5 137 .88 2200 106.1 152 . .90 2300 107.7 169 .92 2400 109.7 191 .94 2500 111.7 215 .97 2600 113.7 245 1.00 2700 116.3 275 1.02 2800 118.9 306 1.05 2900 121.7 338 1.08 3000 124.8 370 1.12 3100 128.5 402 1.16 3200 132.3 435 1.19 3300 136.5 469 1.23 3400 140.5 504 1.27 3500 144.8 539 1.32 Table 13 gives similar information for the swing. In this, the distance being fixed, the actual times for the various items can be used. The "items independent of distance" (column 5) are as follows : "Out" 47 minutes per trip "Out delay" 01 minutes per trip "Spot" 1.75 minutes per trip "Spot delay" 05 minutes per trip -"Unhook" 75 minutes per trip Total 3.03 minutes per trip 22 UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION TABLE 12 Influence of Variations in Size of Log on Total Yarding Time per Trip for Different Distances STUDY B Total time of trip, minutes Time cost per M.B.M. gross, minutes Volume of log, ' Distance in feet 9 Distance in feet 9 gross scale, Scribner, feet, b.m. 100 500 900 1100 100 500 900 1100 100 3.55 6.30 8.75 9.80 35.46 63.00 87.53 98.04 200 3.55 6.33 8.80 9.86 17.76 31.65 44.00 49.29 300 3.56 6.36 8.85 9.91 11.87 21.19 29.82 33.04 400 3.58 6.41 8.93 10.01 8.94 16.02 22.32 25.03 500 3.59 6.46 9.01 10.11 7.17 12.90 18.02 20.23 600 3.61 6.53 9.14 10.26 6.01 10.89 15.24 17.11 700 3.62 6.61 9.27 10.42 5.18 9.44 13.24 14.88 800 3.65 6.71 9.43 10.62 4.56 8.38 11.80 13.27 900 3.68 6.81 9.61 10.83 4.08 7.57 10.48 12.03 1000 3.70 6.91 9.79 11.01 3.70 6.92 9.79 11.01 1100 3.73 7.02 9.97 11.24 3.39 6.38 9.06 10.22 1200 3.76 7.14 10.22 11.55 3.13 5.98 8.53 9.60 1300 3.80 7.33 10.49 11.86 2.92 5.64 8.06 9.12 1400 3.84 7.48 10.75 12.17 2.74 5.34 7.68 8.68 1500 3.89 7.66 11.05 12.53 2.59 5.11 7.36 8.35 1600 3.93 7.85 11.37 12.90 2.46 4.91 7.09 8.06 1700 3.98 8.06 11.72 13.33 2.34 4.74 6.90 7.85 1800 4.04 8.28 12.08 13.75 2.24 4.59 6.70 7.64 1900 4.10 8.52 12.49 14.24 2.16 4.48 6.56 7.49 2000 4.18 8.80 12.95 14.78 2.09 4.40 6.48 7.39 2100 4.26 9.10 13.46 15.38 2.03 4.33 6.41 7.32 2200 4.37 9.51 14.13 16.18 1.99 4.32 6.42 7.35 2300 4.49 9.96 14.89 17.08 1.95 4.32 6.47 7.42 2400 4.65 10.54 15.86 18.28 1.94 4.39 6.61 7.61 2500 4.82 11.18 16.93 19.49 1.93 4.47 6.76 7.79 2600 5.02 11.96 18.23 21.04 1.93 4.60 7.01 8.09 2700 5.21 12.74 19.55 22.63 1.93 4.72 7.25 8.38 2800 5.42 13.55 20.91 24.21 1.94 4.84 7.36 8.65 2900 5.64 14.40 22.32 25.89 1.94 4.96 7.70 8.93 3000 5.87 15.25 23.75 27.58 1.95 5.08 7.92 9.19 Influence on Time of Variations in Size of Trees from which Loos are Made Table 14 shows the influence of tree diameter breast high on costs. It has been prepared in exactly the same manner as table 7 except for the minor and obvious changes necessitated by the use of two donkeys and their crews in the present instance. The times for the yarder and the swing cannot be combined, since their crews are of different size, and it is only after translating into dollars and cents that a total can be obtained. This translation and the resulting total eost has already been indicated in table 1. The final columns of table 14, » This distance does not include the 300 feet hauled by the swing. BULLETIN 371] TH E RELATIVE COST OF YARDING TIMBER 23 however, again show that a thousand feet, b.m., of logs from 18-inch trees is from six to eight times as expensive to handle as from 48-inch trees. TABLE 13 Influence of Variations in Size of Log on Time of Swing per Trip STUDY B Volume of log, gross scale, Scribner, feet, b.m. Time per trip in minutes "Hook" "In" "In delay" Items independent of of volume Total, exclusive of "general delays" Total including 9.6 per cent for "general delays" 100 1.55 .65 .27 3.03 5.05 6.03 200 1.65 .65 .29 3.03 5.62 6.16 300 1.76 .65 .31 3.03 5.75 6.31 400 1.88 .65 .33 3.03 5.89 6.46 500 2.01 .65 .35 3.03 6.04 6.62 600 2.15 .65 .37 3.03 6.20 6.80 700 2.30 .65 .39 3.03 6.37 6.98 800 2.45 .65 .41 3.03 6.54 7.17 900 2.61 .66 .43 3.03 6.73 7.37 1000 2.76 .66 .45 3.03 6.90 7.55 1100 2.93 .66 .46 3.03 7.08 7.76 1200 3.11 .66 .48 3.03 7.28 7.98 1300 3.30 .66 .50 3.03 7.49 8.21 1400 3.50 .66 .52 3.03 7.71 8.45 1500 3.70 .67 .54 3.03 7.94 8.69 1600 3.91 .67 .56 3.03 8.17 8.94 1700 4.12 .67 .57 3.03 8.39 9.20 1800 4.34 .68 .59 3.03 8.64 9.47 1900 4.58 .68 .61 3.03 8.90 9.75 2000 4.81 .69 .63 3.03 9.14 10.03 2100 5.06 .69 .65 3.03 9.43 10.33 2200 5.36 .70 .68 3.03 9.77 10.70 2300 5.70 .70 .70 3.03 10.13 11.10 2400 6.07 .71 .73 3.03 10.54 11.55 2500 6.49 .71 .77 3.03 11.00 12.05 2600 6.93 .72 .81 3.03 11.49 12.59 2700 7.43 .73 .86 3.03 12.05 13.21 2800 7.95 .74 .94 3.03 12.66 13.87 2900 8.51 .74 1.02 3.03 13.30 14.57 3000 9.11 .75 1.11 3.03 14.00 15.35 STUDY C This study was made under conditions which differed radically from those already described. The yarding area, as will be seen from the map of figure 4, was fairly typical of the west side of the central Sierra and is characterized by broken topography and steep slopes up which the timber was hauled to the railroad located near the ridge top. The timber was a mixed stand of sugar pine, western yellow pine (California white pine), Douglas fir, white fir, and incense cedar, 24 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION averaging about 39 m.b.m. per acre for the area actually yarded. The maximum size of the logs was nearly twice as large as it was in Studies A and B, and the trees were much taller. TABLE 14 Influence of Variations in Tree Diameter on Time of Yarding a Distance of 500 .Feet and Swinging STUDY B Swing Total time per M.B.M., Same "Spot" and "spot delay" 3urved, Yard- Same less Total includ- Tree diam- eter breast high, inches Gross scale of logs, Scrib- ner, M.B.M. ing; time all items, (Table 12), minutes Time all items, (Table 13), minutes 1.8 for "spot" and "spot delay," minutes Time for steam sawing, minutes cor- rected to be propor- tional to steam sawing, minutes ing revised "spot" and "spot delay," minutes Yarder minutes Swing minutes Yarder minutes Swing mimites 18 20 22 24 26 28 30 32 .161 .279 .464 .526 .647 1.009 1.150 1.351 6.3 6.3 6.4 6.5 6.6 6.9 7.1 7.4 6.1 6.3 6.6 6.7 6.9 7.6 7.9 8.3 4.3 4.5 4.8 4.9 5.1 5.8 6.1 6.5 5.0 5.1 8.0 8.3 8.8 12.7 13.7 14.7 .6 .6 1.0 1.0 1.1 1.6 1.7 1.8 4.9 5.1 5.8 5.9 6.2 7.4 7.8 8.3 39.2 22.6 13.8 12.4 10.2 6.8 6.2 5.5 30.4 18.3 12.5 11.2 9.6 7.3 6.8 6.1 39.2 22.5 15.5 11.5 9.2 7.8 6.9 6.3 30.4 18.5 13.5 10.7 9.0 8.0 7.3 6.7 34 .503 1.425 6.5 7.5 14.0 6.6 7.1 13.7 4.8 5.3 10.1 16.5 2.0 12.1 7.3 6.3 5.9 1.928 6.4 36 .559 1.616 6.5 7.9 6.7 9.0 4.9 7.2 2.175 14.4 15.7 12.1 17.8 2.2 14.3 6.6 6.6 5.7 6.1 38 .640 1.792 6.6 8.3 6.9 9.5 5.1 7.7 2.432 14.9 16.4 12.8 19.3 2.4 15.2 6.1 6.2 5.5 5.8 40 .694 1.941 6.6 8.6 7.0 9.9 5.2 8.1 2.635 15.2 16.9 13.3 20.8 2.5 15.8 5.8 6.0 5.4 5.6 42 .789 2.119 6.7 9.2 7.1 10.4 5.3 8.6 2.908 15.9 17.5 13.9 22.7 2.8 16.7 5.5 5.7 5.3 5.5 44 2.094 1.723 9.1 8.1 10.3 9.3 8.5 7.5 3.817 17.2 19.6 16.0 30.0 3.7 19.7 4.5 5.2 5.2 5.3 46 .845 1.441 1.991 6.8 7.5 8.8 7.3 8.6 10.0 5.5 6.8 8.2 4.277 23.1 25.9 20.5 26.4 3.2 23.7 5.4 5.6 5.1 5.2 48 .917 1 . 586 2.149 6.8 7.8 9.3 7.4 8.9 10.5 5.6 7.1 8.7 4.652 23.9 26.8 21.4 28.9 3.7 25.1 5.1 5.4 5.0 5.1 BULLETIN 371] THE RELATIVE COST OF YARDING TIMBER 25 Fig. 4. — Contour map of yarding area of Study C, showing (A) railroad, (B) landing, (C) bucking chutes, CD) positions of yarder, (E) positions of swing, and the positions of the yarding line. Scale, 1 inch equals 450 feet. 26 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION The study covered a full setting of the yarder, or about 43 acres, the engine shifting its position to the opposite end of the landing when about half of the timber had been removed. An additional minor shift in position was made (as indicated on the map) to avoid the necessity of using a bull block on certain of the turns. The yarding engine was a 12 by 14 "Humboldt Yarder" manufactured by the Willamette Iron and Steel Works. This narrow-drum type of machine permitted the use of a "fair lead" which made it possible to dispense with a bull block on a large number of trips. A swing donkey, a 12 by 14 simple-geared, wide-drum Willamette reader, was used in a manner similar to that of Study B, its hauling distance being about 350 feet. The haul of the swing was, however, parallel to the track so that the hauling distance of the yarder was not materially reduced thereby. Its function was, therefore, merely to relieve the yarder of the duty of spotting for the steam saw. Logs were normally handled one at a time. The average load per trip was 1283 feet b.m. gross scale. The operation required 15% days for both yarder and swing. The location of the railroad, landing, bucking chute ; yarder, swing, etc., are shown on the map. The crew employed was as follows : Yarder Swing 1 hooktender 1 engineer 1 engineer 1 fireman 1 fireman 1 wood haul teamster 1 wood haul teamster 1 wood haul team 1 wood haul team 1 unhooker 3 riggers 1 frogger 1 frogger 1% frog shoveler 10 1 choker hole digger 1 whistle punk The data obtained, similar in general to that of the studies pre- viously described, is summarized in table 15, which, however, gives somewhat less detail as to the causes of the delays. Table 16 is a summary for the swing. io Two frog shovelers were used on 15 out of 25 days and one on the remainder. BULLETIN 371] TH E RELATIVE COST OF YARDING TIMBER 27 TABLE 15 Distribution of Time between Operations Involved in Yarding STUDY C Operation Average time per trip — minutes Per cent of total time Average time per occurrence — minutes Out 1.16 1.16 .20 .76 .96 2.58 .12 2.70 .22 .22 .97 .97 .52 .09 .06 1.58 .15 .03 .24 1.03 .90 4.60 10.61 10.9 10.9 1.9 7.2 9.1 24.3 1.1 25.4 2.1 2.1 9.1 9.1 4.9 .9 .6 14.9 1.4 .3 2.3 9.7 8.4 43.4 100.0 1.16 Shift .20 Hook .76 Total time between out and in In outside of block 2.58 In inside of block .39 Total in Block .75 Unhook .97 Delays — Out Shift Hook In outside of block In inside of block Block Unhook General — Line changes 21.95 Miscellaneous Total delays Total time per trip TABLE 16 Distribution of Time between Operations Involved in Swinging STUDY C Operation Average time per trip — minutes Per cent of total time Average time per occurrence — minutes Out ; .41 .41 4.44 4.44 .96 .96 1.97 1.97 1.10 1.10 .13 1.11 .17 .03 .76 2.20 11.08 3.7 3.7 40.0 40.0 8.6 8.6 17.8 17.8 10.0 10.0 1.1 10.2 1.5 .2 6.9 19.9 100.0 .41 Hook 4.94 In .96 Spot 2.09 Unhook 1.17 Delays — Out In Spot Unhook General Total delays Total time per trip 23 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION Influence on Time of Variations in Distance which Log is Hauled The analysis of the yarder figures to determine the influence of variations of distance is summarized in table 17, which may be com- pared to tables 3, 4, and. 10. In the present instance it will be noted that "hook" appears as one of the variables, although previously treated as a constant. The variation in the values of this item which necessitated this treatment may be the result of the longer yarding TABLE 17 Influence of Variations in Distance on Total Time of Yarding per Trip STUDY C Time per trip, minutes Dis- tance, feet "Out" "Out delay" "In" "In delay" "Hook" Items indepen- dent of distance Total, exclusive of general delays Total including 22.1 per cent for general delays 50 .37 .40 .22 .14 .69 2.08 3.90 4.76 100 .40 .40 .37 .22 .69 2.08 4.16 5.08 150 .44 .41 .52 .29 .69 2.08 4.43 5.41 200 .48 .42 .67 .37 .69 2.08 4.71 5.75 250 .53 .42 .82 .45 .69 2.08 4.99 6.10 300 .57 .43 .97 .54 .69 2.08 5.28 6.45 350 .62 .43 1.13 .63 .69 2.08 5.58 6.81 400 .67 .44 1.29 .72 .69 2.08 5.89 7.19 450 .72 .45 1.45 .80 .69 2.08 6.19 7.55 500 .78 .46 1.62 .88 .69 2.08 6.51 7.95 550 .84 .47 1.78 .97 .69 2.08 6.83 8.34 600 .91 .48 1.95 1.06 .69 2.08 7.17 8.75 650 .97 • .49 2.12 1.15 .69 2.08 7.50 9.16 700 1.02 .50 2.29 1.25 .69 2.08 7.83 9.56 750 1.08 .51 2.47 1.35 .69 2.08 8.18 9.99 800 1.15 .52 2.64 1.44 .69 2.08 8.52 10.40 850 1.22 .53 2.82 1.54 .69 2.08 8.88 10.84 900 1.28 .54 3.00 1.64 .69 2.08 9.23 11.27 950 1.35 .55 3.18 1.73 .70 2.08 9.59 11.70 1000 1.43 .56 3.37 1.83 .71 2.08 9.98 12.19 1050 1.51 .57 3.56 1.93 .72 2.08 10.37 12.65 1100 1.59 .58 3.75 2.04 .73 2.08 10.77 13.15 1150 1.67 .59 3.95 2.15 .75 2.08 11.19 13.66 1200 1.75 .60 4.15 2.26 .77 2.08 11.61 14.19 1250 1.84 .62 4.36 2.37 .79 2.08 12.06 14.72 1300 1.93 .63 4.57 2.48 .81 2.08 12.50 15.27 1350 2.03 .65 4.78 2.59 .84 2.08 12.97 15.83 1400 2.13 .67 5.00 2.70 .88 2.08 13.46 16.43 1450 2.24 .68 5.24 2.82 .93 2.08 13.99 17.09 1500 2.35 .70 5.48 2.94 .99 2.08 14.54 17.76 1550 2.47 .72 5.73 3.07 1.06 2.08 15.13 18.50 1600 2.59 .74 5.98 3.20 1.14 2.08 15.73 19.20 1650 2.73 .75 6.25 3.33 1.23 2.08 16.37 19.99 1700 2.88 .77 6.52 3.47 1.34 2.08 17.06 20.82 1750 3.03 .79 6.80 3.62 1.47 2.08 17.79 21.71 1800 3.18 .81 7.12 3.76 1.62 2.08 18.57 22.67 Bulletin 371] THE relative COST OF YARDING TIMBER 29 distances involved in Study C, for tbe time of the "hook" is uniform for the shorter distances. It seems more probable, however, that this increase for the greater distances is accidental and due to the very rough topography at points most remote from the landing (fig. 4). The constant "items independent of distance" (column 7) are in this case: 1 ' Shift ' ' 20 minutes 1 'Block" 22 minutes "In" inside of block 12 minutes "Unhook" 97 minutes "Shift delay" 09 minutes "Hook delay" 06 minutes "Block delay" 03 minutes "In delay" inside of block 15 minutes "Unhook" delay" 24 minutes Total 2.08 minutes Since the general delays amount to 18.1 per cent of the total time (table 15). the pro-rating coefficient for use in the final column is .181 1.000 — .181 = .221. Influence on Time of Variations in Size of Log Table 18 shows the influence of the size of log hauled on the items which are directly affected thereby, that is the "in," "in delay," and "hook." This table. corresponds to tables 5 and 11. The larger size of the timber handled in Study C permits the statement in table 18 of values up to nearly 6000 feet, or almost double the maximum size of the previous studies. Table 19 corresponds to tables 7 and 12 and shows the effect of variations in the volume of the log hauled on the complete yarding time per trip for different distances. On account of the greater yarding distances involved in the present study, columns are in this instance given for trip distances of 100, 900, and 1800 feet, or the approximate minimum, average, and maximum for the study. It will be observed that, for a third time, the conclusions stated on page 14 are confirmed. Table 20 gives similar information for the swing and may be com- pared with table 13. The "items independent of volume" (column 5), are as follows : "Out" 41 minutes per trip "Out delay" 13 minutes per trip "Spot" 1.97 minutes per trip "Spot delay" „ .17 minutes per trip "Unhook" 1.10 minutes per trip "Unhook" delays 03 minutes per trip Total 3.81 minutes per trip 30 UNIVERSITY OF CALIFORNIA- EXPERIMENT STATION The pro-rating coefficient of 7.4 per cent (final column) is based on the fact that the general delays amount to 6.9 per cent of the total time : .069 k 000 — .069 .074 ) TABLE 18 Influence of Variations in Size of Log on Yarding Times Affected Thereby STUDY C "In," "In delay", Volume of log, per cent of per cent of gross scale, average time for average time for "Hook," Scribner, corresponding corresponding minutes feet, b.m. distances distances 100 97.5 39 .64 200 97.7 41 .66 300 98.0 43 .68 400 98.2 45 .69 500 98.4 48 .70 600 98.7 51 .71 700 98.9 55 .73 800 99.1 59 .74 900 99.3 64 .75 1000 99.5 68 .75 1100 99.7 73 .76 1200 99.8 78 .77 1300 99.9 84 .78 1400 100.1 91 .78 1500 100.2 99 .79 1600 100.3 108 .79 1700 100.5 118 .80 1800 100.6 130 .80 1900 100.7 142 .81 2000 100.9 156 .81 2100 101.0 172 .81 2200 101.1 185 .82 2300 101.3 199 .82 2400 101.4 211 .82 2500 101.5 224 .82 2600 101.6 236 .82 2700 101.7 245 .83 2800 101.9 255 .83 2900 102.0 265 .83 3000 102.0 273 .83 3100 102.1 280 .83 3200 102.1 287 .83 3300 102.2 294 .83 3400 102.2 299 .83 3500 102.3 304 .83 3600 102.3 308 .83 3700 102.4 312 .83 3800 102.4 315 .83 3900 102.5 317 .83 4000 102.5 319 .83 4100 102.6 320 .83 4200 102.6 320 .83 4300 102.6 321 .83 4400 102.7 321 .83 4500 102.7 321 .83 4600 102.7 321 .83 4700 102.7 322 .83 4800 102.7 322 .83 4900 102.7 322 .83 5000 102.7 322 .83 5100 102.7 322 .83 5200 102.7 322 .83 5300 102.8 322 .83 5400 102.8 322 .83 5500 102.8 322 .83 5600 102.8 322 .83 5700 102.8 322 .83 5800 102.8 322 .83 5900 102.8 322 .83 Bulletin 371] THE RELATIVE COST OF YARDING TIMBER 31 TABLE 19 Influence of Variations in Size of Log on Total Yarding Time per Trip for Different Distances STUDY C Volume Total time of trip, minutes Time cost per M.B.M. gross, minutes of log, Distance in feet 11 Distance in feet 11 gross scale, Soribner, feet, b.m. 100 900 1800 100 900 1800 100 5.97 9.81 15.76 59.70 98.10 157.60 200 5.99 9.87 15.87 29.95 49.35 79.35 300 6.01 9.94 16.00 20.03 33.13 53.33 400 6.04 9.99 16.10 15.10 25.00 40.25 500 6.06 10.06 16.25 12.12 20.12 32.50 600 6.09 10.17 16.50 10.15 16.95 27.50 700 6.12 10.26 16.69 8.74 14.66 23.84 800 6.14 10.36 16.89 7.68 12.95 21.11 900 6.17 10.45 17.09 6.85 11.61 18.99 1000 6.19 10.57 17.33 6.19 10.57 17.33 1100 6.21 10.71 17.66 5.65 9.75 16.06 1200 6.24 10.82 17.91 5.20 9.02 14.93 1300 6.26 10.96 18.19 4.82 8.43 13.98 1400 6.29 11.07 18.51 4.49 7.92 13.23 1500 6.32 11.23 18.89 4.21 7.49 12.59 1600 6.35 11.46 19.31 3.97 7.16 12.06 1700 6.39 11.66 19.78 3.76 6.86 11.63 1800 6.41 11.91 20.39 3.56 6.62 11.33 1900 6.46 12.17 21.00 3.40 6.42 11.06 2000 6.51 12.44 21.63 3.25 6.22 10.82 2100 6.56 12.77 22.34 3.12 6.08 10.64 2200 6.61 13.04 22.98 3.00 5.93 10.44 2300 6.64 13.32 23.60 2.89 5.79 10.26 2400 6.67 13.62 24.18 2.78 5.68 10.07 2500 6.70 13.89 24.87 2.68 5.56 9.96 2600 6.74 14.13 25.42 2.59 5.44 9.78 2700 6.77 14.37 25.89 2.51 5.32 9.60 2800 6.80 14.54 26.32 2.43 5.20 9.39 2900 6.83 14.71 26.72 2.36 5.08 9.20 3000 6.85 14.88 27.14 2.28 4.97 9.05 3100 6.88 15.02 27.46 2.22 4.85 8.87 3200 6.89 15.18 27.79 2.15 4.75 8.69 3300 6.91 15.31 28.12 2.09 4.64 8.53 3400 6.93 15.41 28.35 2.02 4.54 8.34 3500 6.96 15.50 28.57 1.99 4.43 8.16 3600 6.97 15.59 28.75 1.94 4.33 7.99 3700 6.99 15.68 28.94 1.89 4.24 7.82 3800 6.99 15.73 29.08 1.84 4.14 7.65 3900 7.00 15.77 29.16 1.79 4.05 7.48 4000 7.00 15.81 29.27 1.75 3.98 7.33 4100 7.00 15.84 29.32 1.71 3.87 7.15 4200 7.00 15.84 29.32 1.67 3.77 6.98 4300 7.01 15.88 29.43 1.63 3.69 6.85 4400 7.01 15.88 29.43 1.59 3.61 6.69 4500 7.01 15.88 29.43 1.56 3.53 6.54 4600 7.01 15.90 29.47 1.52 3.45 6.41 4700 7.01 15.90 29.47 1.49 3.38 6.27 4800 7.01 15.91 29.47 1.46 3.31 6.14 4900 7.01 15.91 29.47 1.47 3.25 6.02 5000 7.01 15.91 29.47 1.40 3.18 5.90 5100 7.01 15.91 29.47 1.38 3.12 5.78 5200 7.01 15.91 29.47 1.35 3.06 5.67 5300 7.01 15.91 29.47 1.32 3.00 5.57 5400 7.01 15.91 29.47 1.30 2.95 5.46 5500 7.01 15.91 29.47 1.28 2.89 5.36 5600 7.01 15.91 29.47 1.25 2.84 5.27 5700 7.01 15.91 29.47 1.23 2.79 5.18 5800 7.01 15.91 29.47 1.21 2.75 5.09 ii This distance does not include the 350 feet hauled by the swing. H2 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION TABLE 20 Influence of Variations in Size of Log on Time of Swing per Trip STUDY C Time per trip in minutes Volume of log, Total gross scale, Items Total, including Scribner, "Hook" "In" "In delay" independent exclusive of 7.4 per cent feet, b.m. of volume "general delays ' ' for "general delays" 100 2.93 .70 .80 ' 3.81 8.94 9.60 200 3.02 .72 .83 3.81 9.08 9.76 300 3.12 .74 .85 3.81 9.22 9.91 400 3.22 .75 .87 3.81 9.35 10.05 500 3.33 .77 .90 3.81 9.51 10.22 600 3.45 . .78 .92 3.81 9.66 10.39 700 3.59 .80 .94 3.81 9.84 10.58 800 3.73 .81 .97 3.81 10.02 10.78 900 3.85 .83 .99 3.81 10.18 10.93 1000 3.96 .84 1.01 3.81 10.32 11.10 1100 4.09 .86 1.03 3.81 10.49 11.27 1200 4.24 .87 1.06 3.81 10.68 11.47 1300 4.40 .88 1.08 3.81 10.87 11.68 1400 4.57 .89 1.10 3.81 11.07 11.90 1500 4.75 .90 1.12 3.81 11.28 12.11 1G00 4.92 .91 1.15 3.81 11.49 12.34 1700 5.10 .92 1.17 3.81 11.70 12.58 1800 5.27 .93 1.19 3.81 11.90 12.79 1900 5.50 .93 1.22 3.81 12.16 13.06 2000 5.65 .94 1.24 3.81 12.34 13.27 2100 5.82 .94 1.27 3.81 12.54 13.49 2200 5.98 .95 1.32 3.81 12.76 13.70 2300 6.12 .96 1.39 3.81 12.98 13.95 2400 6.25 .96 1.47 3.81 13.19 14.17 2500 6.39 .97 1.56 3.81 13.43 14.43 2600 6.50 .97 1.67 3.81 13.65 14.66 2700 6.62 .98 1.79 3.81 13.90 14.93 2800 6.73 .98 1.95 3.81 14.17 15.21 2900 6.82 .98 2.12 3.81 14.43 15.51 3000 6.89 .99 2.28 3.81 14.67 15.75 3100 6.95 .99 2.45 3.81 14.90 16.10 3200 7.00 .99 2.62 3.81 15.12 16.25 3300 7.00 .99 2.79 3.81 15.29 16.42' 3400 7.00 1.00 2.96 3.81 15.47 16.60 3500 7.00 1.00 3.13 3.81 15.64 16.80 3600 7.00 1.00 3.30 3.81 15.81 17.00 3700 7.00 1.00 3.47 3.81 15.98 17.18 3800 7.00 1.00 3.64 3.81 16.15 17.35 3900 7.00 1.00 3.81 3.81 16.32 17.54 4000 7.00 1.00 3.98 3.81 16.49 17.70 4100 7.00 1.00 4.15 3.81 16.66 17.90 4200 7.00 1.00 4.32 3.81 16.83 18.09 4300 7.00 1.00 4.49 3.81 17.00 18.26 4400 7.00 1.00 4.66 3.81 17.17 18.44 4500 7.00 1.00 4.83 3. SI 17.34 18.63 4600 7.00 1.00 5.00 3.81 • 17.51 18.82 4700 7.00 1.00 5.17 3.81 17.68 19.00 4800 7.00 1.00 5.34 3.81 17.85 19.18 4900 7.00 1.00 5.51 3.81 18.02 19.37 5000 7.00 1.00 5.69 3.81 18.20 19.55 5100 7.00 1.00 5.87 3.81 18.38 19.74 5200 7.00 1.00 6.04 3.81 18.55 19.92 5300 7.00 1.00 6.22 3.81 18.73 20.14 5400 7.00 1.00 6.39 3.81 18.90 20.31 5500 7.00 1.00 6.57 3.81 19.08 20.49 5600 7.00 1.00 6.74 3.81 19.25 20.68 5700 7.00 1.00 6.91 3.81 19.42 20.88 5800 7.00 1.00 7.08 3.81 19.59 21.05 5900 7.00 1.00 7.25 3.81 19.76 21.21 bulletin 371] the relative cost of yarding timber 33 Influence on Time of Variations in Size of Trees from which Logs are Made The ratios between the figures in both tables 19 and 20 for small and large logs are of approximately the same order of magnitude as in Studies A and B. Comparing, for example, the time per trip (900 feet) of a 2000 12 feet b.m. log as compared with a 100 foot log, it is observed that Study A indicates (table 6) that the former is about 1.43 times as great. In Study B (tables 12 and 13) the same ratios for yarder and swing are 1.48 and 1.66 respectively, and in Study C (tables 19 and 20), 1.27 and 1.38. When the figures are expressed on a tree instead of on a log basis, however, a considerable difference is apparent. This is due not so much to differences in topography and machinery as to those inherent in the timber itself. In Study C the trees were much taller, and therefore those of small diameter were considerably greater in volume than in the case of either Study A or B. Table 21 gives in its first two columns the average volume per tree typically encountered in the last study, and the method of subdividing it into logs. The practice indicated was not rigidly followed and these figures should be considered merely as approximate averages. The remaining columns of the table are derived in the manner already described in connection with table 7. The final columns show that the 18-inch trees cost 5.4 and 4.3 times as much for yarder and swing respectively as do the 48-inch trees. If 18-inch and 48-inch trees in the present study had been identical in height and volume with those of Studies A and B, the time per m.b.m. required by the yarder to handle them would have been 61.2 and 3.5 minutes, respectively, while that by the swing would have been 50.5 and 8.4. The ratios under these conditions would have been 8.1 for the yarder and 6.0 for the swing, or nearly the same as in the previous instances. It is evident, therefore, that were the relative cost of small trees and large expressed on the basis of the volume per tree rather than on that of the diameter, the results of the three studies would be in even closer agreement. 12 This is about the largest size commonly handled. The values for still larger logs are in somewhat less striking agreement. 34 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION TABLE 21 Influence of Variations in Tree Diameter on Time of Yarding a Distance of 900 Feet and Swinging STUDY C Gross scale of logs, Scrib- ner, M.B.M. Yard- ing; time all items, (Table 19), minutes Swing Total time per M.B.M., Same ( Time all items, (Table 20), minutes Same less 2.14 for "spot" and "spot delay," minutes Time for steam sawing, minutes "Spot" and "spot delay" cor- rected to be propor- tional to steam Total includ- ing revised "spot" and "spot delay," minutes /urved, Tree diam- eter breast high, inches Yarder minutes Swing minutes Yarder minutes Swing minutes sawing, minutes 18 20 22 24 26 28 30 .300 .400 .520 .700 .900 1.150 1.450 9.94 9.99 10.08 10.26 10.45 10.76 11.15 9.91 10.05 10.25 10.58 10.93 11.37 12.00 7.77 7.91 8.11 8.44 8.79 9.23 9.86 5.70 6.90 8.20 10.00 11.50 13.20 15.00 .63 .76 .91 1.10 1.27 1.46 1.66 8.40 8.67 9.02 9.54 10.06 10.69 11.52 33.1 25.0 20.8 14.7 11.6 9.3 7.7 28.0 21.7 17.4 13.6 11.2 9.3 7.9 33.1 26.0 19.7 15.3 12.4 10.7 9.6 28.0 21.7 17.4 13.8 11.6 10.2 9.1 32 1.040 .760 10.63 10.32 11.17 10.70 9.03 8.56 16.70 1.85 19.44 11.6 10.8 8.9 1.800 20.95 21.87 17.59 8.4 34 1.280 .920 10.93 10.47 11.63 10.96 9.49 8.82 18.70 2.06 20.37 9.7 9.3 8.3 2.200 21.40 22.59 18.31 8.0 36 1.510 1.090 11.25 10.70 21.95 12.13 11.25 9.99 9.11 20.50 2.27 21.37 8.4 8.2 7.9 2.600 23.38 19.10 7.5 38 1.740 1.260 11.76 10.90 12.66 11.59 24.25 10.52 9.45 22.50 2.49 22.46 7.5 7.5 7.6 3.000 22.66 19.97 7.2 40 2.000 1.450 12.44 11.08 23.52 13.27 12.00 11.13 9.86 24.40 2.70 23.69 6.8 6.9 7.3 3.450 25.27 20.99 7.0 42 2.290 1.660 13.29 11.58 13.92 12.48 26.40 11.78 10.34 26.50 2.93 25.05 6.3 6.7 7.0 3.950 24.87 22.12 6.9 44 2.550 1.850 4.400 14.01 12.04 14.54 12.92 12.40 10.78 23.18 28.50 3.15 26.33 5.9 6.0 6.7 26.05 27.46 6.7 46 1.770 1.710 1.420 11.83 11.68 11.10 12.73 12.60 11.94 10.59 10.46 9.80 30.50 3.37 34.22 7.1 7.0 6.4 4.900 34.61 37.27 30.85 6.6 48 1.950 1.890 1.560 12.30 12.14 11.37 13.16 13.03 12.25 11.02 10.89 10.11 32.30 3.57 35.59 6.6 6.6 6.1 5.400 35.81 38.44 32.02 6.5 Bulletin 371] the relative cost of yarding timber 35 GENERAL CONSIDERATIONS AND CONCLUSIONS Conditions vary widely between different lodging operations even within a given region. It is therefore futile to try to prepare general figures which are of exact applicability everywhere. The foregoing discussion illustrates, however, the fact that analyzed figures on details will often apply where totals will not. The total cost of yarding was quite unlike in the three studies, yet both the relation between the costs for different distances and that between the costs for different sizes were essentially the same. It is for this reason, as well as to support the conclusions stated on page 3. that the foregoing tables with their large amount of detail have been presented. There is much information therein which may prove of value to lumbermen who are studying their operations with a view to increase efficiency. It would be easy, for example, to construct from them revised tables (similar to table 21) which would be applicable to any hauling distance and to trees of any height. It is of interest to consider again the statement made in Bulletin 339, "The Relative Cost of Making Logs from Small and Large Timber" (see footnote, page 3) as to the probable causes which underlie the high costs per m.b.m. associated with the yarding of small trees. These are three in number, as follows: (1) The Scribner log rule (and also the Spaulding) is ultra- conservative in the values assigned to small logs; if an over-run of 6 per cent is to be expected from 48-inch trees, as much as 24 per cent should be obtained from 3 8-inch trees. Were the results of table 1 expressed in terms of lumber tally instead of in terms of log scale, therefore, the average cost of yarding logs from the smallest size trees would be only S 1 /^ times instead of 6% times that of logs from the largest. (2) The yield in lumber per cubic foot of actual volume is smaller for small trees than for large on account of the greater percentage of waste involved in sawing lumber therefrom. Costs per cubic foot of volume would be less unfavorable to the small sizes and on this basis the ratio between costs for 18-inch and 48-inch trees is further reduced to 3.8 to 1. This fact is of little significance, however, in connection with present day manufacturing methods, though of course of possible future importance. (3) The remaining important factor is the large amount of time which must be spent on every tree and on every log regardless of its 36 UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION size and which in the case of the small trees must be charged against the small volume obtainable. In conclusion it should be stated that the foregoing figures were not collected with the idea of proving any theory. They were gathered in connection with a general investigation of the factors affecting the cost of logging. These factors are many but from the commencement of the compilation of the data it was evident that tree size was of prime importance in almost every phase of a logging operation. Studies by other investigators 13 indicate that a similar condition prevails in the sawmill and it is well known that the quality of the lumber produced from small trees is inferior. 14 There are considerable differences between the practices of lumber operators in removing or leaving the smaller trees encountered. Some log practically every tree large enough to produce a saw log, while others leave standing everything below a rather flexible diameter limit. Within recent years the tendency in California has been toward closer and closer utilization in this respect, although little exact information as to its desirability has been available. While the present study is perhaps not conclusive, since only certain phases of lumber manufacture have been investigated, the figures presented herewith suggest forcibly that the present policy has been carried too far and that a more conservative plan would be financially profitable. 1 s Show, S. B., "An Analysis of the Cost of Sawing Logs," Timberman, July, 1922, page 40. I* Berry, Swift, "A Study of the Grades of Lumber Produced from Cali- fornia Pine, Fir and Cedar," Lumberman, March, 1918, pages 36 and 37, and April, 1918, pages 39 and 40.