864:
959:
113:, with the largest commercial harbour tugboats in the 2000-2010s having around 60 to 65 short tons-force (530–580 kN; 54–59 tf) of bollard pull, which is described as 15 short tons-force (130 kN; 14 tf) above "normal" tugboats. The worlds strongest tug since its delivery in 2020 is Island Victory (Vard Brevik 831) of
971:
This method eliminates much of the uncertainties of the practical trial. However, any numerical simulation also has an error margin. Furthermore, simulation tools and computer systems capable of determining bollard pull for a ship design are costly. Hence, this method makes sense for larger shipyards
954:
See Figure 2 for an illustration of error influences in a practical bollard pull trial. Note the difference in elevation of the ends of the line (the port bollard is higher than the ship's towing hook). Furthermore, there is the partial short circuit in propeller discharge current, the uneven trim of
144:
is not sufficient to understand how strong a tug is – this is because the tug operates mainly in very low or zero speeds, thus may not be delivering power (power = force × velocity; so, for zero speeds, the power is also zero), yet still absorbing torque and delivering thrust. Bollard pull values are
987:. There, bollard pull is often a category in competitions and gives an indication of the power train efficiency. Although conditions for such measurements are inaccurate in absolute terms, they are the same for all competitors. Hence, they can still be valid for comparing several craft.
580:
482:
384:
949:
in propeller discharge race. If part of the discharge race is sucked back into the propeller, efficiency decreases sharply. This could occur due to a trial that is performed in too shallow water or too close to a
875:. It is limited in precision - a number of boundary conditions need to be observed to obtain reliable results. Summarizing the below requirements, practical bollard pull trials need to be conducted in a
59:
rating of a car, it is a convenient but idealized number that must be adjusted for operating conditions that differ from the test. The bollard pull of a vessel may be reported as two numbers, the
117:, with a bollard pull of 477 tonnes-force (526 short tons-force; 4,680 kN). Island Victory is not a typical tug, rather it is a special class of ship used in the petroleum industry called an
202:
942:
of the ship, the conditions of the propeller discharge race and the tension in the towing line must have settled to a constant or near-constant value for a reliable measurement.
923:
The geometry of the towing line must have a well-defined value. Ideally, one would expect it to be exactly horizontal and straight. This is impossible in reality, because
641:
612:
1166:
Please note that the velocity of air or water is not necessarily equal to the velocity of the ship as the velocity of wind and water currents must be added vectorially
844:
815:
786:
757:
728:
699:
670:
285:
258:
231:
488:
390:
292:
1155:
1080:
933:
the two fixed points of the line, being the bollard on shore and the ship's towing hook or cleat, may not have the same height above water.
902:
discharge. If the ship were too close to a wall, water could rebound back, creating a propulsive wave. This would falsify the measurement.
75:
bollard pull, the average of measurements over an interval of, for example, 10 minutes. An equivalent measurement on land is known as
43:
through a tow-line, commonly measured in a practical test (but sometimes simulated) under test conditions that include calm water, no
1205:
1135:
905:
The ship must be in deep water. If there were any ground effect, the measurement would be falsified. The same holds true for
788:
is resistance coefficient of air resistance (usually quite high, >0.9, as ships are not designed to be aerodynamic)
1180:
124:
For vessels that hold station by thrusting under power against a fixed object, such as crew transfer ships used in
1156:
https://www.man-es.com/docs/default-source/marine/5510-0004-04_18-1021-basic-principles-of-ship-propulsion_web.pdf
1230:
1220:
975:
Both methods can be combined. Practical trials can be used to validate the result of numerical simulation.
161:
56:
1054:
955:
the ship and the short length of the tow line. All of these factors contribute to measurement error.
1225:
916:
must have a well-defined value, as it influences the specific weight of the water and thereby the
1088:
1029:
984:
619:
590:
876:
575:{\displaystyle R_{A}={\frac {1}{2}}\times C_{A}\times \rho _{a}\times V_{a}^{2}\times A_{a}}
477:{\displaystyle R_{R}={\frac {1}{2}}\times C_{R}\times \rho _{w}\times V_{w}^{2}\times A_{s}}
379:{\displaystyle R_{F}={\frac {1}{2}}\times C_{F}\times \rho _{w}\times V_{w}^{2}\times A_{s}}
822:
793:
764:
735:
706:
677:
648:
263:
236:
209:
1110:
8:
939:
125:
76:
1200:
156:
Effective towing power is equal to total resistance times velocity of the ship.
103:
91:
1235:
1006:
906:
83:
1206:
Bollard Pull by Capt. P. Zahalka, Association of
Hanseatic Marine Underwriters
879:, ideally not at the mouth of a river, on a calm day with hardly any traffic.
1214:
946:
884:
36:
146:
109:
Bollard pull is primarily (but not only) used for measuring the strength of
28:
983:
Practical bollard pull tests under simplified conditions are conducted for
863:
79:
1001:
150:
32:
141:
87:
52:
20:
899:
86:, which is used to measure the total horizontal force generated by a
48:
958:
898:
that intends to move the ship forward must only be generated by the
927:
913:
872:
114:
110:
95:
47:, level trim, and sufficient depth and side clearance for a free
40:
19:
is a conventional measure of the pulling (or towing) power of a
996:
867:
Figure 1: bollard pull trial under ideal (imaginary) conditions
895:
99:
24:
1181:"Bollard Pull Trial Code for tugs with Steerprop propulsion"
1024:
1022:
917:
888:
871:
This method is useful for one-off ship designs and smaller
846:
is the cross-sectional area of the ship above the waterline
118:
44:
1019:
855:
Values for bollard pull can be determined in two ways.
1081:"Western Marine to build tugboat, vessel for Ctg port"
206:
Total resistance is the sum of frictional resistance,
140:
Unlike in ground vehicles, the statement of installed
1201:
International
Standard for Bollard Pull trials - 2019
945:
One condition to watch out for is the formation of a
825:
796:
767:
738:
709:
680:
651:
622:
593:
491:
393:
295:
266:
239:
212:
164:
67:
bollard pull – the highest force measured – and the
1151:
1149:
962:Figure 2: bollard pull trial under real conditions
838:
809:
780:
751:
730:is resistance coefficient of frictional resistance
722:
693:
664:
635:
606:
574:
476:
378:
279:
252:
225:
196:
938:Conditions must be static. The engine power, the
1212:
759:is resistance coefficient of residual resistance
1146:
883:The ship needs to be in undisturbed water.
1073:
978:
972:and for the design of a series of ships.
957:
920:moved by the propeller per unit of time.
862:
1213:
672:is the velocity of (relative to) water
106:), which is utilized to move a load.
39:under full power, on a shore-mounted
701:is the velocity of (relative to) air
128:maintenance, an equivalent measure "
197:{\displaystyle P_{E}=R_{T}\times V}
13:
1173:
1047:
858:
149:-force (written as t or tonne) or
14:
1247:
1194:
119:Anchor Handling Tug Supply vessel
1160:
1128:
1103:
891:would falsify the measurement.
850:
817:is the wetted area of the ship
1:
1087:. 4 June 2012. Archived from
966:
135:
1030:"Bollard Pull - an overview"
7:
990:
10:
1252:
636:{\displaystyle \rho _{a}}
607:{\displaystyle \rho _{w}}
1012:
614:is the density of water
233:, residual resistance,
23:. It is defined as the
985:human powered vehicles
979:Human-powered vehicles
963:
926:the line falls into a
868:
840:
811:
782:
753:
724:
695:
666:
637:
608:
576:
478:
380:
281:
260:, and air resistance,
254:
227:
198:
961:
866:
841:
839:{\displaystyle A_{a}}
812:
810:{\displaystyle A_{s}}
783:
781:{\displaystyle C_{A}}
754:
752:{\displaystyle C_{R}}
725:
723:{\displaystyle C_{F}}
696:
694:{\displaystyle V_{a}}
667:
665:{\displaystyle V_{w}}
643:is the density of air
638:
609:
577:
479:
381:
282:
280:{\displaystyle R_{A}}
255:
253:{\displaystyle R_{R}}
228:
226:{\displaystyle R_{F}}
199:
126:offshore wind turbine
1231:Nautical terminology
1055:"Rotor Tug "RT Zoe""
1034:ScienceDirect Topics
823:
794:
765:
736:
707:
678:
649:
620:
591:
489:
391:
293:
264:
237:
210:
162:
1221:Physical quantities
1111:"MV ISLAND VICTORY"
1061:. 13 September 2006
558:
460:
362:
35:(kN)) exerted by a
1140:Windcat Work Boats
1117:. 11 December 2019
964:
930:due to its weight;
877:deep water seaport
869:
836:
807:
778:
749:
720:
691:
662:
633:
604:
572:
544:
474:
446:
376:
348:
277:
250:
223:
194:
102:, (specifically a
513:
415:
317:
51:stream. Like the
1243:
1190:
1188:
1187:
1167:
1164:
1158:
1153:
1144:
1143:
1132:
1126:
1125:
1123:
1122:
1107:
1101:
1100:
1098:
1096:
1091:on 15 April 2016
1077:
1071:
1070:
1068:
1066:
1051:
1045:
1044:
1042:
1040:
1026:
845:
843:
842:
837:
835:
834:
816:
814:
813:
808:
806:
805:
787:
785:
784:
779:
777:
776:
758:
756:
755:
750:
748:
747:
729:
727:
726:
721:
719:
718:
700:
698:
697:
692:
690:
689:
671:
669:
668:
663:
661:
660:
642:
640:
639:
634:
632:
631:
613:
611:
610:
605:
603:
602:
581:
579:
578:
573:
571:
570:
557:
552:
540:
539:
527:
526:
514:
506:
501:
500:
483:
481:
480:
475:
473:
472:
459:
454:
442:
441:
429:
428:
416:
408:
403:
402:
385:
383:
382:
377:
375:
374:
361:
356:
344:
343:
331:
330:
318:
310:
305:
304:
286:
284:
283:
278:
276:
275:
259:
257:
256:
251:
249:
248:
232:
230:
229:
224:
222:
221:
203:
201:
200:
195:
187:
186:
174:
173:
132:" may be given.
1251:
1250:
1246:
1245:
1244:
1242:
1241:
1240:
1226:Water transport
1211:
1210:
1197:
1185:
1183:
1179:
1176:
1174:Further reading
1171:
1170:
1165:
1161:
1154:
1147:
1134:
1133:
1129:
1120:
1118:
1115:Island Offshore
1109:
1108:
1104:
1094:
1092:
1085:The Independent
1079:
1078:
1074:
1064:
1062:
1053:
1052:
1048:
1038:
1036:
1028:
1027:
1020:
1015:
993:
981:
969:
861:
859:Practical trial
853:
830:
826:
824:
821:
820:
801:
797:
795:
792:
791:
772:
768:
766:
763:
762:
743:
739:
737:
734:
733:
714:
710:
708:
705:
704:
685:
681:
679:
676:
675:
656:
652:
650:
647:
646:
627:
623:
621:
618:
617:
598:
594:
592:
589:
588:
566:
562:
553:
548:
535:
531:
522:
518:
505:
496:
492:
490:
487:
486:
468:
464:
455:
450:
437:
433:
424:
420:
407:
398:
394:
392:
389:
388:
370:
366:
357:
352:
339:
335:
326:
322:
309:
300:
296:
294:
291:
290:
271:
267:
265:
262:
261:
244:
240:
238:
235:
234:
217:
213:
211:
208:
207:
182:
178:
169:
165:
163:
160:
159:
138:
115:Island Offshore
104:ballast tractor
92:heavy machinery
12:
11:
5:
1249:
1239:
1238:
1233:
1228:
1223:
1209:
1208:
1203:
1196:
1195:External links
1193:
1192:
1191:
1175:
1172:
1169:
1168:
1159:
1145:
1127:
1102:
1072:
1059:Marineline.com
1046:
1017:
1016:
1014:
1011:
1010:
1009:
1007:Tractive force
1004:
999:
992:
989:
980:
977:
968:
965:
952:
951:
943:
936:
935:
934:
931:
921:
910:
907:propeller walk
903:
892:
860:
857:
852:
849:
848:
847:
833:
829:
818:
804:
800:
789:
775:
771:
760:
746:
742:
731:
717:
713:
702:
688:
684:
673:
659:
655:
644:
630:
626:
615:
601:
597:
569:
565:
561:
556:
551:
547:
543:
538:
534:
530:
525:
521:
517:
512:
509:
504:
499:
495:
471:
467:
463:
458:
453:
449:
445:
440:
436:
432:
427:
423:
419:
414:
411:
406:
401:
397:
373:
369:
365:
360:
355:
351:
347:
342:
338:
334:
329:
325:
321:
316:
313:
308:
303:
299:
274:
270:
247:
243:
220:
216:
193:
190:
185:
181:
177:
172:
168:
137:
134:
84:tractive force
9:
6:
4:
3:
2:
1248:
1237:
1234:
1232:
1229:
1227:
1224:
1222:
1219:
1218:
1216:
1207:
1204:
1202:
1199:
1198:
1182:
1178:
1177:
1163:
1157:
1152:
1150:
1141:
1137:
1136:"Windcat MK1"
1131:
1116:
1112:
1106:
1090:
1086:
1082:
1076:
1060:
1056:
1050:
1035:
1031:
1025:
1023:
1018:
1008:
1005:
1003:
1000:
998:
995:
994:
988:
986:
976:
973:
960:
956:
948:
947:short circuit
944:
941:
937:
932:
929:
925:
924:
922:
919:
915:
911:
908:
904:
901:
897:
893:
890:
886:
882:
881:
880:
878:
874:
865:
856:
831:
827:
819:
802:
798:
790:
773:
769:
761:
744:
740:
732:
715:
711:
703:
686:
682:
674:
657:
653:
645:
628:
624:
616:
599:
595:
587:
586:
585:
582:
567:
563:
559:
554:
549:
545:
541:
536:
532:
528:
523:
519:
515:
510:
507:
502:
497:
493:
484:
469:
465:
461:
456:
451:
447:
443:
438:
434:
430:
425:
421:
417:
412:
409:
404:
399:
395:
386:
371:
367:
363:
358:
353:
349:
345:
340:
336:
332:
327:
323:
319:
314:
311:
306:
301:
297:
288:
272:
268:
245:
241:
218:
214:
204:
191:
188:
183:
179:
175:
170:
166:
157:
154:
152:
148:
143:
133:
131:
127:
122:
120:
116:
112:
107:
105:
101:
97:
93:
90:, a piece of
89:
85:
81:
78:
74:
70:
66:
62:
58:
54:
50:
46:
42:
38:
34:
30:
26:
22:
18:
1184:. Retrieved
1162:
1139:
1130:
1119:. Retrieved
1114:
1105:
1093:. Retrieved
1089:the original
1084:
1075:
1063:. Retrieved
1058:
1049:
1037:. Retrieved
1033:
982:
974:
970:
953:
870:
854:
583:
485:
387:
289:
205:
158:
155:
139:
130:bollard push
129:
123:
108:
72:
68:
64:
60:
27:(usually in
17:Bollard pull
16:
15:
1002:Kort nozzle
894:The static
851:Measurement
151:kilonewtons
33:kilonewtons
1215:Categories
1186:2011-08-24
1121:2022-12-31
967:Simulation
887:or strong
145:stated in
142:horsepower
136:Background
94:such as a
88:locomotive
73:continuous
53:horsepower
31:-force or
21:watercraft
1095:19 August
1065:19 August
900:propeller
873:shipyards
625:ρ
596:ρ
560:×
542:×
533:ρ
529:×
516:×
462:×
444:×
435:ρ
431:×
418:×
364:×
346:×
337:ρ
333:×
320:×
189:×
49:propeller
991:See also
928:catenary
914:salinity
885:Currents
111:tugboats
1039:1 April
940:heading
584:Where:
98:, or a
96:tractor
77:drawbar
65:maximum
57:mileage
41:bollard
997:Azipod
912:Water
153:(kN).
147:tonnes
69:steady
61:static
37:vessel
29:tonnes
1236:Force
1013:Notes
950:wall.
896:force
889:winds
100:truck
82:, or
25:force
1097:2013
1067:2013
1041:2021
918:mass
80:pull
45:tide
287:.
71:or
63:or
55:or
1217::
1148:^
1138:.
1113:.
1083:.
1057:.
1032:.
1021:^
121:.
1189:.
1142:.
1124:.
1099:.
1069:.
1043:.
909:.
832:a
828:A
803:s
799:A
774:A
770:C
745:R
741:C
716:F
712:C
687:a
683:V
658:w
654:V
629:a
600:w
568:a
564:A
555:2
550:a
546:V
537:a
524:A
520:C
511:2
508:1
503:=
498:A
494:R
470:s
466:A
457:2
452:w
448:V
439:w
426:R
422:C
413:2
410:1
405:=
400:R
396:R
372:s
368:A
359:2
354:w
350:V
341:w
328:F
324:C
315:2
312:1
307:=
302:F
298:R
273:A
269:R
246:R
242:R
219:F
215:R
192:V
184:T
180:R
176:=
171:E
167:P
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
