A sheet bend joins two rope ends by passing one end through a bight in the other rope, around both parts of that bight and under its own standing part. This calculator performs transparent arithmetic on selected reference values; it does not calculate knot strength, working load or suitability.
Sheet Bend Selected Reference Arithmetic
Explore selected reference arithmetic while viewing a continuously connected sheet-bend topology.
Equation Used
- All four inputs are selected reference values.
- The retained fraction is applied directly to the entered line reference.
- The divided reference is purely the retained reference divided by the selected divisor.
- Rope strength, knot behavior, working load, suitability and safety are excluded.
The retained fraction and divisor are selected comparison parameters, not measured efficiency or a safety factor.
Connected sheet-bend topology
The animation keeps each rope continuous while the smaller orange rope passes up through the blue bight, around both parts and under itself. The two short ends finish on the same side. Crossing masks disclose the intended over-under order while a bounded tightening motion changes only the illustrated dressing.
U.S. Army guidance limits the single sheet bend to two dry ropes of unequal size and warns that it may loosen or slip when tension is released; it identifies the double sheet bend for broader conditions.
What the calculator determines
Select a weaker-line reference M, a retained fraction f, a divisor d and a comparison load P. The calculator reports Mf, Mf/d, 100P/(Mf/d), and the signed difference Mf/d−P.
These are entered-value comparisons only. None is a working-load limit, rating or prediction of the tied joint.
Selected-value arithmetic
R = Mf; D = R/d; comparison = 100P/D; signed difference = D−P.
Selected-input arithmetic
For M = 20 kN, f = 55%, d = 5 and P = 2 kN, the retained reference is 11 kN, the divided reference is 2.2 kN, the comparison is about 90.91%, and the signed difference is 0.2 kN.
No strength or safety claim
The retained fraction and divisor are user selections, not measured knot efficiency or a safety factor. Actual performance depends on rope material, construction, diameter pairing, condition, wetness, knot variant, dressing, tail length, cyclic loading, inspection and application. Use manufacturer data, applicable standards, competent instruction and testing for real work; do not derive a working load from this page.
Questions
Is the divided reference a working-load limit?
No.
Does the calculator predict sheet-bend strength?
No.
Can a single sheet bend loosen?
Yes; Army guidance warns it may loosen or slip when tension is released.
Primary and authoritative references
- U.S. Coast Guard Auxiliary Boat Crew Qualification Guide — official seamanship qualification guidance identifying the sheet (becket) bend for joining a heaving line to a towline and requiring correctly dressed bends with adequate bitter ends.
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