Adventioneering

The very first thing that you need to understand is that none of the line that you are going to put on your winch was not made for it. Rather than recently be designed for the purpose, synthetic line has been around for a long time in its primary industries of marine and industrial rigging.

In some cases vendors have adopted a snake oil like approach to synthetic line; re-branded commercial line and selling it at a great markup, while concealing it’s origins with confusing trade names. If you must depend on the line you should understand exactly what it is, and where it came from.

Synthetic line was only adopted recently that the off-road community realized they could replace the steel line they were getting from the winch manufacturers – no doubt probably provided primarily due to steel line’s low cost – with synthetic line. Whoever had the idea deserves a beer.

Synthetic line has many advantages. You can kink it with no reduction in strength (it just returns to shape). It weighs significantly less than steel line; 30m of 9.5mm line usually weighs only ~ 1.5-2 kg. This means you can throw it, rather than drag it.

Both steel and synthetic winch cables can be broken, synthetic a little more so because it can be abraded by terrain or bits of the vehicle. Drawn across a tight enough piece of rock and loaded, it can be cut. The primary difference though is that you can tie two pieces of synthetic line together, whereas there is no trail repair for a broken steel rope.

Steel rope generally must be fed from a roller fairlead. Synthetic line will run fine from a roller fairlead, but damage to the rollers can injure the line. Some operators prefer to replace the roller fairlead with a hawse fairlead to prevent this problem. I view this as good practice, but stop short of calling it essential.

When the line breaks, what happens is much different between steel and synthetic line. Besides the load becoming suddenly unsecured, the risk of a break is that the line can whip and cause damage and injury. Steel line stretches more than synthetic line and therefore carries more energy with which to whip. A synthetic line will whip, but with much less force. Generally if weighted with a blanket, it will fall right to the ground.

When I cut my Masterpull line in the great Reiter incident of 2007, I simply tied a figure-8 bight in the end of the line from the winch, and put a D-shackle through it. I then cut off the hook and tied a pair of figure-8 bights in the broken section, resulting in a winch extension. This ultimately was responsible for my still being able to self-recover.

Alternatively if your winch opening on the hawse was large enough, you could tie the two ends together and run the knot right onto the drum. You can also splice the rope together yourself, using a simple technique that is relatively easy to learn.

Steel line rusts. Synthetic line won’t rust, but it will break down over time when exposed to UV radiation, as any rock climber will be able to tell you. Most synthetic lines sold have UV coatings (since the line was intended to be used on marine vessel rigging and exposed to the sun for countless days on end). Boats however tend to be used at sea-level, and UV radiation increases dramatically as altitude increases. 8-12% per 1000 meters of elevation gained. Thus synthetic line used at higher elevations will receive more exposure, so some care should be given to this subject.

From the perspective of protecting the line, the best solution besides going with a reliable high-grade line, is to protect it while it’s on the drum. You are likely to be driving around a lot more than winching, so if your line is protected from sunlight during this time, it will have a considerable lifespan. The Superwinch on Remington mounts “inside” the box bumper, so the line is protected from the light. If your winch mounts on top of your bumper (classic with Jeep’s), consider purchasing a cover, or sheathing the last 10-20’ of line so that the portion exposed on the drum is protected.

On balance I feel the UV exposure angle is overplayed, given the industrial nature of the product and it’s intended use. The manufacturer coatings are well researched and sufficient on a quality line, and the environment the line was specified for is much harsher in general than conditions encountered in off-road use.

The other disadvantage to synthetic winch line is that it can melt. Steel line is very resistant to effects from heat likely to be encountered on the trail. The exact temperature at which the line melts will be made available by the manufacturer. Dyneema fibers (Amsteel Blue) melt at 147.2°C.

The primary problem is that planetary gear driven winches used under power-out conditions employ a brake to keep the winch from slipping. If this action is friction based and causes the winch to heat up, possibly enough to melt the line. Worm-gear winches are immune to this problem, as are several winches with external brakes (e.g., Superwinch EP9). A winch of any design will not heat up significantly when powering in, only powering out a load.

Some off-road vendors address this problem by splicing say 5 or 7 meters of high-temp line to the regular winch line. The reasoning is that as the drum heats up, the first set of wraps will be temperature resistant. Personally I think this is a dubious premise for several reasons, but it does not cost very much extra and could be considered cheap insurance on a planetary winch.

The original of your winch line is likely to be this; an off-road vendor has purchased the line in bulk from the manufacturer. They cut off winch-length sections, splice a thimble into one end, put a hook on it, and mark it all up and sell it back to you. In catering to the market some manufacturers will also dye the rope a color; for example Amsteel Blue is always blue from the manufacturer, but is available in the off-road market in a variety of colors.

There is a lot of hocus-pocus about what size line and strength rating you need. A lot of these bar-room figures involve the weight of your vehicle, which is materially irrelevant. It does not take a rope with a 3500kg rating to winch a vehicle that weighs 3500kg; it takes a rope of that strength to dangle it in the air. When recovering a stuck vehicle the winch need only overcome the rolling/dragging resistance of the winched vehicle, which typically is very low but sometimes can be dramatically higher than the weight of the winched vehicle.

This should have been taken into consideration when the winch itself was sized; so all one need do is purchase synthetic line that is rated at least as much as the winch itself. In general I recommend doubling the winch strength to find the line requirement; e.g. 18,000lb breaking strength for a 9,000lb winch.

Another bit of dubious bar-room math is that using a pulley doubles the force on the line, so you need to use a really large line to be safe when using a snatch block. This is untrue. The load on any segment of the line is cut in half. The load on the snatch block is equal to the weight of the load, as well as is its connection to the anchor.

For example, if you use a single snatch block on a 1000kg load, each segment of the line will carry 500kg of weight. The anchor (and pulley) will be loaded with 1000kg. This sort of setup is used either to double the power of the winch (9000lb winch can move a 18,000lb load with 2:1 advantage), or to half the load so the winch has an easier time of it.

The bulk going rate for 9.5mm Amsteel Blue from off-road vendors is $2 to $2.50 per foot. It is worth noting that it can be had from marine suppliers for as low as $1.40 per foot. If you plan on finishing your own end; either simply tying a bight which is aesthetically unpleasant but totally safe and functional, or by properly splicing in a thimble, it would thus be better to seek out a marine supply house. Many marine suppliers will also be able to splice a thimble if you are unable or unwilling to learn the skill.

Prices for finished winch lines from off-road vendors often run from about $2.10 to as much as $4 per foot. Know what you are buying, and beware snake-oil vendor claimed UV or abrasion coatings.

The two major fiber players for synthetic line are Dyneema and Technora. Technora has a higher temperature rating than Dyneema. Technora is often spliced to Dyneema (which is lighter and cheaper) as previously discussed to produce a two-part rope that has temperature resistance on the first set of winds on the drum.

Dyneema is produced by DSM (www.dsm.com), and is the basis for the ubiquitous Amsteel Blue line. Technora is a product of Teijin Twaron (Aramid) (www.twaron.com).

Many winch lines sold by off-road vendors are openly Amsteel Blue, but sometimes the situtation is a little more opaque. Masterpull “Liquid Crystal Plasma” line is made of Dynex, a line designed mooring and tugboats. Dynex is ultimately Dyneema.

Perhaps the last criterion for selecting a synthetic line is thickness. Thicker is not always stronger, or better. A thinner line will let you get more of it on the drum. My advice is to select your manufacturer or vendor, and then buy the thinnest line that meets your strength requirement (as previous, 2x winch strength). For 9000lb winches this is typically going to be 9.5mm.

This article is part of the Vehicle Dependent Expedition section.