Towing Bridle & Line Calculator
Size towing gear for safe marine towing operations
Towing Gear Requirements
Minimum Towline Diameter
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Towline Length
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Bridle Leg Length
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Bridle Line Diameter
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Bridle Spread Angle
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Estimated Tow Load
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Required Breaking Strength
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Shackle Size (min)
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Nylon Line Breaking Strength
| Diameter | 3-Strand | Double Braid | Working Load |
|---|---|---|---|
| 1/2" | 5,750 lb | 7,000 lb | ~1,150 lb |
| 5/8" | 8,900 lb | 10,500 lb | ~1,780 lb |
| 3/4" | 12,800 lb | 15,000 lb | ~2,560 lb |
| 7/8" | 17,500 lb | 20,000 lb | ~3,500 lb |
| 1" | 22,600 lb | 26,000 lb | ~4,520 lb |
| 1-1/4" | 35,000 lb | 40,000 lb | ~7,000 lb |
Safe Towing Practices
Towing Setup
Use bridle on tow boat to distribute load to both stern cleats
Secure towline to bow eye or samson post on towed vessel
Keep personnel clear of towline at all times
Maintain a knife ready to cut line in emergency
Towing Operation
Start slow and gradually increase speed
Adjust towline length to keep vessels in sync with waves
Have someone on towed vessel if possible
Use VHF to communicate between vessels