Mobility · Practice evening · Basic
Knots, Lashings and Cordage That Hold
Samson's 5:1 or 10:1 safety factors, a bowline near 55% of unknotted strength in the 9 mm study, and why none of those numbers make climbing on them acceptable.
This is for educational purposes only. Not professional medical, electrical, or safety advice.
Warning
Breaking strength is not a working-load limit, and knot-efficiency figures are test results, not guarantees. Do not use utility cordage, camp lashings or these outlines for climbing, fall arrest, rescue or suspended loads.
- 01
Start with rated rope, inspection and the right application
Samson warns against damaged rope, shock loading, sharp corners and standing in the recoil path. Its general guidance discusses safety factors of 5:1 or 10:1 — 20% or 10% of quoted spliced breaking strength under appropriate conditions — and those are not automatically safe allowances for knotted, weathered cord or life-safety systems.
- 02
Bowline: a fixed loop, not a universal rescue connection
A primary experimental paper tested 9 mm polyethylene, polypropylene, mixed-fiber laid rope and polyethylene braid, and its abstract estimates bowline strength at roughly 55% of dry unknotted strength after its stated normalization — not a universal 55% rating. Material, construction, dressing, loading and security all change results, and cyclic slack loading or slippery cord needs special caution. Do not publish a life-safety bowline procedure without an application-specific authority.
- 03
Clove hitch: positioning and lashing attachment
Use it only where the attachment geometry and sustained loading suit it; changing direction, slack cycles, or unsuitable pole and cord surfaces can allow movement. A transferable efficiency percentage and safe load were unconfirmed, so do not assign it a generic '60% strength' number.
- 04
Taut-line hitch: adjustable guyline tension, not lifting
Its holding power depends on friction between the hitch and the standing line, so very slick cord, an unsuitable diameter, or changing conditions can undermine it. Verified load and efficiency numbers were not obtained — use rated tensioning hardware whenever slipping could injure someone or release important cargo.
- 05
Trucker's hitch: tensioning leverage, not free strength
A loop and return line create mechanical advantage, but friction, loop choice, anchor geometry and rope bending determine the real forces. A universal actual 3:1 advantage or retained-strength percentage is unconfirmed, and tightening harder can overload the weakest component. Do not use it to lift people or suspend loads overhead.
- 06
Square and shear lashings: choose by structural function
A square lashing connects crossing spars; a shear lashing connects spars meant to open into a pair of legs. Security depends on sound spars, cordage, tight wraps, frapping, terminations, geometry, bracing and ground support, and no defensible universal load rating was verified for either. Keep applications non-life-critical: racks, camp fixtures and temporary supports, not occupied towers, bridges or overhead lifting.
- 07
Count knots, wetting and fiber separately
Samson says some knots can remove up to 50% of rope strength and stresses that losses vary with fibers and construction. The experimental study's wet samples were soaked for 12 hours under 2.0 kg/cm² pressure — a test condition that should not be generalized to ordinary rain — so a blanket 'wet rope loses X%' rule is unconfirmed. Get the actual rope maker's wet-strength data.