TOWING EQUIPMENT CALCULATION
The calculation shall be to comply with the requirement of Maritime Safety Committee-MSC/Circ, 884 “Guidance Notes For Towage At Sea”
Calculation of Towage Resistance ：
It shall be under the condition, the towage speed is 9kn and the draught is 7m; in the still water, when calculate the Towage Resistance
=1.15
Main/Spare Towing Wire Cable
BP=2400KN
Main and Spare Wire Cable were supplied by Owner. And the minimum Breaking Loading is 2400KN.
Towing Bridle Chain
The towing equipment, consists of 2 sets towing bridle chain, triangle plate, intermediate pennant, link shackles and recovery wire, is to be provided. Each towing bridle chain consists of Stud common link, abt. 30m; two ends of it have the end link and pear shaped link. Towing bracket and pear shaped link are connected directly. Towing bridle chain and triangle plate are
connected by joining shackle.
The breaking load of towing bridle chain is not less than the breaking load of main towing cable wire. Towing bridle is used by stud weld chain, φ 84mm; the material is anchor chain steel,Class 3; the breaking load is 5160kN
Intermediate Pennant
4860 kN
＞
4800 kN
The intermediate pennant is used by Wire Cable, φ
90mm, 8X61+IWR1870; the breaking
load is 4860 kN
＞
4800 kN.
Closing Turnbuckle is provided on the two ends of the Steel Wire, one end is connected by joining shackle and triangle plate, another end is connected by joining shackle and towing wire cable.
Towing Bracket
The Towing Bracket is to be able to withstand a breaking load not less than 1.3 the weakest part of Main Towing Wire Cable.
4860
×
1.3
＝
6084kN
The Max. breaking load of Towing Bracket is to be calculated according to the breaking load of Towing Bridle Chain
Joining Shackle
The joining shackle is to be able to withstand a breaking load not less than 1.5 the Max. breaking load of Towing Wire Cable, and shall be add 10% shock load. The Max. breaking load of joining shackle is to be calculated the according to the breaking load of towing bridle chain.The type of shackle is cast piece, and the material is high strength alloy steel, 20CrMo.
Triangle Plate Strength
The Triangle Plate is to be able to withstand a breaking load not less than 1.5 the Max.breaking load of Main Towing Wire Cable.
The type of shackle is forge piece, and the Max. breaking load. P
d＝5160×1.5＝7740 kN.
The material is high strength alloy steel, 20CrMo
The calculation shall be to comply with the requirement of Maritime Safety Committee-MSC/Circ, 884 “Guidance Notes For Towage At Sea”
Calculation of Towage Resistance ：
It shall be under the condition, the towage speed is 9kn and the draught is 7m; in the still water, when calculate the Towage Resistance
=1.15
Main/Spare Towing Wire Cable
BP=2400KN
Main and Spare Wire Cable were supplied by Owner. And the minimum Breaking Loading is 2400KN.
Towing Bridle Chain
The towing equipment, consists of 2 sets towing bridle chain, triangle plate, intermediate pennant, link shackles and recovery wire, is to be provided. Each towing bridle chain consists of Stud common link, abt. 30m; two ends of it have the end link and pear shaped link. Towing bracket and pear shaped link are connected directly. Towing bridle chain and triangle plate are
connected by joining shackle.
The breaking load of towing bridle chain is not less than the breaking load of main towing cable wire. Towing bridle is used by stud weld chain, φ 84mm; the material is anchor chain steel,Class 3; the breaking load is 5160kN
Intermediate Pennant
4860 kN
＞
4800 kN
The intermediate pennant is used by Wire Cable, φ
90mm, 8X61+IWR1870; the breaking
load is 4860 kN
＞
4800 kN.
Closing Turnbuckle is provided on the two ends of the Steel Wire, one end is connected by joining shackle and triangle plate, another end is connected by joining shackle and towing wire cable.
Towing Bracket
The Towing Bracket is to be able to withstand a breaking load not less than 1.3 the weakest part of Main Towing Wire Cable.
4860
×
1.3
＝
6084kN
The Max. breaking load of Towing Bracket is to be calculated according to the breaking load of Towing Bridle Chain
Joining Shackle
The joining shackle is to be able to withstand a breaking load not less than 1.5 the Max. breaking load of Towing Wire Cable, and shall be add 10% shock load. The Max. breaking load of joining shackle is to be calculated the according to the breaking load of towing bridle chain.The type of shackle is cast piece, and the material is high strength alloy steel, 20CrMo.
Triangle Plate Strength
The Triangle Plate is to be able to withstand a breaking load not less than 1.5 the Max.breaking load of Main Towing Wire Cable.
The type of shackle is forge piece, and the Max. breaking load. P
d＝5160×1.5＝7740 kN.
The material is high strength alloy steel, 20CrMo
