Line and rope
From KayakWiki
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- This page discusses line in the sense of rope. For other uses of the term see Line (disambiguation page).
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Line is the word used to describe a cable, rope, string, cord, or wire used aboard a ship.
There are several types of line construction:
- Single braid - braided rope without a core. Cheap stuff - don't bother except for very light use. See tarp.
- Double braid - line that has a braided core with a braided sheath. Common in marine shops for small craft.
- Kernmantle - line that has straight (static rope) or twisted (dynamic rope) fibers in the core with a braided sheath. Common in climbing rope.
- Laid rope - three or more strands of line twisted into a single, larger line. Common in hardware stores - don't bother.
Strictly speaking, double braid is a form of kernmantle, but I separated it since it is the form useful for everything in kayaking but rescue and tow rope.
Materials used in lines include:
| Material | Properties | Suitable for Kayaking |
|---|---|---|
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Polyester |
Typically 90% as strong as nylon, good stretch, excellent UV resistance and stable when wet |
excellent choice for kayaking. |
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Dacron |
brand name for polyester. |
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Nylon |
Strong, good stretch, good UV resistance but changes length when wet |
Ok where wet stretch is not a problem. |
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Polypropylene |
Light, relatively weak and stretchy. Floats well, doesn't hold water. |
Good for tow rope and throw rope in braid form. Laid polypro rope is useless. |
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Spectra™ |
High Molecular Density Polyethylene. Very strong, low stretch but expensive. Prone to creep over time under load. Slippery and doesn't hold knots as well as polyester. |
Limited uses in kayaking - sometimes mixed with polypropylene for stronger, lighter throw ropes. |
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Spectra™ blend |
Spectra sheath with other fibers in the weave. Cordura™ can be added to improve grip and knot holding power. |
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Dyneema™ |
Name for Spectra in Europe. |
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Kevlar |
Very strong and stiff. Doesn't melt. Weakened when knotted or run over a tight bend as in a carabiner. Poor UV performance. Doesn't wear as well as others. |
No |
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Vectran |
Strong, low stretch and little creep. Good abrasion and fatigue performance. Poor UV performance. |
No |
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Natural Fibers |
Hemp, etc. Prone to rot unless treated with messy stuff. |
Don't bother. |
Dynamic vs Static
Climbing rope is available in both static and dynamic types. Dynamic rope has a higher stretch and can absorb shock - it is used to protect climbers in a fall. Static rope is used where very low stretch and little shock absorption is required. Rescue rope should be static. Only when high-angle rescue is done, for example in rescuing a paddler from a steep ravine, should dynamic rope be considered. You have to weight the risk of a fall against the risk of loading up a springy line that will snap back if it breaks or lets go.
Climber's ropes are usually made of nylon, including accessory cord that looks good for kayaking. Accessory cord is static.
Strength Ratings
If you are concerned with the strength of line, climbing rope is rated using UIAA (Union Internationale Des Association D'Apinisme) standards. These indicate a minimum strength for the rope. Marine line also has ratings available from various manufacturers. Rope from hardware stores is usually unrated and is not likely to be strong. Rated ropes will almost always be more expensive than unrated - buy accordingly.
Cutting and finishing line
A line will always be too long until it's cut - then it will be too short. Therefore, avoid cutting lines.
When you cut the end of a line, the braid will fray considerably. For a very heavy line, you can whip the end. A whipping is made by wrapping a very light line tightly around the end. Some folks will use shrink wrap (used for electrical stuff) to do the same, but that's not durable. However, for light line, you can simply heat the end of the line to melt it and fuse the fibers together. Try not to get a big ball of melted plastic at the end, as that will never pass through half the stuff you need to feed a line through. You will not be able to melt Kevlar.
Caring for line
Always take care of your lines. After kayaking, they should be allowed to dry in air. If you leave wet line buried under other gear, it will become covered with mould, which can weaken the line. All lines should be kept as clean as possible as dirt can get into the fibers and cut them, weakening the line. Do not step on, drive over or sbuse the line, especially rescue rope. Inspect regularly and replace when showing any signs of wear or degradation.
Lines used in controlling a sail are: sheet, guy and halyard.
Rope is tied together with knots.
