Glenn's Scouting Pages

Glenn Cockwell's Notes on Ropes

Working Loads

Safe Work Loads of Fibre Ropes 3-Strand Ropes Safety factor = 5 (new rope)
Rope Diameter (cm/inches)	Manila	Nylon	Poly-propylene	Polyester	Poly-ethylene
	Kg.	Kg.	Kg.	Kg.	Kg.
0.64 (1/4")	54	136	113	136	114
0.79 (5/16")	90	227	182	227	159
0.95 (3/8")	122	317	227	318	227
1.27 (1/2")	239	567	377	545	363
1.59 (5/8")	400	908	590	863	477
1.91 (3/4")	490	1271	772	1090	681
2.22 (7/8")	699	1725	999	1544	953
2.54 (1")	817	2179	1317	1907	1135

Types of Fibre Ropes

Fibre ropes are made from either natural or synthetic fibres.

	Pros	Cons
Natural Fibres	Resistant to heat Do not burn fast Hold simple knots	Susceptible to rot and mildew Shrink and stiffen when wet
Manila		Weakens when exposed to sunlight
Sisal	Sunlight resistant	Poor handling when wet
	Pros	Cons
Synthetic Fibres	Stronger x3 than Natural fibres Impervious to rot and mildew Lighter Do not stiffen when wet	Slippery when wet
Nylon	Strongest of all fibres Highly elastic and will elongate 10% to 40% High abrasion resistance	Lose 10% of their strength when wet Very slippery when wet Attacked by acids and paints Dangerous when it snaps under load Susceptible to heat and sunlight
Polypropylene	Light Floats on water Will not conduct electricity when dry	Weaker than polyester and nylon Weakens progressively when temperatures rise (+65°C) Low melting point
Polyethylene	Resistant to acids and alkalis	Weakest of synthetic fibres Softens with rising temperatures
Polyester	Lower stretch properties than nylon No strength loss when wet High resistance to sunlight and weather Resistant to acids and alkali	Weaker than nylon under shock load

Safe use and storage

All ropes should be kept dry and away from chemicals
Never overload a rope
A frozen rope should be carefully allowed to thaw and dry before use
A rope should never be dragged over the ground or sharp objects
Avoid abrupt bends if possible as they weaken rope considerably. Pad all sharp corners
Synthetic ropes can be slippery when wet or new. Use additional care when handling or tying knots
Store ropes in a cool dry place with good ventilation. Hang loose coils over a peg
Dry and clean wet rope before storing. Allow them to dry naturally, as too much heat will make the fibres brittle.
Keep all ropes away from any source of heat.
Inspect ropes regularly for extreme wear and cuts
Untwist strands carefully and check for bright clean internal conditions
Pull out a couple of fibres from the end of a rope and try to break them. If they break easily then the rope should not be used when safety is required.

Knots, Bends, and Hitches

All knots bends and hitches reduce the strength of rope

Knots and bends by 50%

Hitches reduce by 25%

Splices by 20%

Monofilament ropes such as polyethylene and polypropylene require special knots to prevent slipping

Cutting Ropes:

Wrap tape around rope at the cutting point and then cut through the tape.

Information taken from a pamphlet issued by the Canada Safety Council and from information shipped with Lehigh rope.