Rigging Load Calculator
Estimate loads on standing and running rigging
Degrees (typical: 10-15°)
Degrees (typical: 12-18°)
Standing Rigging Loads
Righting Moment (RM30)
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Cap Shroud Load (each)
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Forestay Load
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Backstay Load
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Lower Shroud Load
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Mast Compression
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Wire/Rod Sizing
Cap Shroud (1x19 wire)
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Forestay (1x19 wire)
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Cap Shroud (rod)
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Dyneema Alternative
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Wire Breaking Strength (1x19 SS)
| Size | Breaking (lbs) | Working (50%) |
|---|---|---|
| 3/16" | 4,700 | 2,350 |
| 1/4" | 8,200 | 4,100 |
| 9/32" | 10,300 | 5,150 |
| 5/16" | 12,500 | 6,250 |
| 3/8" | 17,500 | 8,750 |
| 7/16" | 24,000 | 12,000 |
| 1/2" | 29,700 | 14,850 |
About Rigging Load Calculations
Righting Moment (RM30): The force resisting heeling at 30 degrees. This is the primary factor in determining rigging loads. RM30 = Displacement x Stability Arm (GZ at 30°).
Safety Factors: Standing rigging should be sized with at least 2.5:1 safety factor (working load = 40% of breaking strength). Offshore boats often use 3:1 or higher.
Load Distribution: Cap shroud load ≈ RM30 / (Shroud span x cos(angle)). Forestay typically sees 1.1-1.3x the cap shroud load due to headsail loads.
Note: These are estimates for initial sizing. Final rigging specification should be done by a qualified rigger or naval architect.