Winch line(s) and fairleads

I checked my roller fairlead for any reason it would be problematic to continue its use with synthetic rope such as burrs, breakage, binding, etc. and found none. Rollers reduce friction and if the roller fairlead is quality, not damaged, and will not allow the rope to fall into one of the corners, there is potentially no reasonable reason to not continue using the roller with synthetic rope. 

There are contrary opinions. If anyone has personal experience (not hearsay) as to why using rollers with synthetic rope is a proven problem, I would like to hear about it. I am a long time (30+ years) rope user (rigging, rescue, rope access) but my extensive rope experience is not with winching. With that said, here is some thoughts and info:

Manufacturers often recommend against certain things solely to limit their liability. Fables get started and are passed down generations. I can discuss many fables regarding rope, including strength, knots, damage, etc. But what it comes down to is the actual use and the hands-on field experience by those that get out and try things. 

Rope is not damaged by running over a properly functioning, smooth roller. An argument can be made that it is superior to a hawse in that the curved surface is of greater circumference and the rolling characteristic reduces friction significantly depending upon the angle of contact.

Now, more on cable vs. synthetic winch line.

Strength of synthetic rope vs. cable: this is a non-issue. Both cable and synthetic rope have a minimum breaking strength (MBS) published by the manufacturer. If measurement/calculation methods are the same, a cable with a MBS of 10,000 lbf. (force) has the same strength as a synthetic rope with a MBS of 10,000 lbf. Much further discussion could be involved here as to how measurements/calculations are made, but I do not believe it is warranted for the overall intent of this information. To say that one type is stronger than another can only be factually made with some form of definable comparison. The statement that synthetic rope is stronger than steel cable is not always true (or vice versa).

Winch capacity: the manufacturers stated maximum pulling capacity of the winch typically with 1 layer of winch line around spool. According to Warn: "Warn winches are rated to pull their maximum load when spooling the first layer of rope onto the winch drum.  An 8000 lb. capacity winch will only pull 8000 lbs. when you are spooling the rope onto the first layer." Warn states an approximate loss of pulling capacity of 15% per layer of winch line. This is due to the increase in the diameter of the "drum" as winch line is sequentially wrapped around the drum changing the effective gear ratio.

Durability: this is dependent upon the use environment, upkeep, etc. A lava bed environment is substantially different from a woods trail or swamp. How much contact with abrasive surfaces will the winch line have? Is the winch used for work/utility purposes such as dragging downed trees to a location to be cut into firewood? Is the winch line only used for positioning or recovering a vehicle? Is it used to position or recover another vehicle? The list is endless. From my perspective, I would lean on the steel cable having a bit better durability overall. I chose steel cable for my winch on the vehicle I use to drag logs through the woods and pull rocks around, etc.

Broken strands: yes, a broken strand of wire rope is potentially hazardous when handling wire rope (think hand injury). A broken strand of synthetic rope poses no puncture hazard to human flesh. Wear suitable snug fitting leather gloves whether you are running wire or synthetic rope.

Dirt: minimize putting any winch line in the dirt/mud. The nature of the environment often makes this difficult to achieve. Many rope manufacturers limit their liability by sticking with old ideas that are not necessarily true. There are old time fables that still exist that say dirt/grit on the interior of a rope/line/winch line will grind and cut the material from the inside out. With certain rope designs, this has been proven to not be fact. Nothing is sawing it from the interior out. It would require substantial, continuous cycling around an object with a significant amount of trapped dirt/grit accumulation to achieve concerning amount of damage. Another concern is fiber on fiber friction. There is no real way to completely prevent this. Keep your winch line clean, inspect it, take care of it, be clean. It is highly doubtful to get dirt/grit accumulation in modern, quality wire rope. Synthetic rope construction typically for winch line use is an open weave braid that can allow dirt/grit penetration to the interior of the rope. Clean the rope after use and follow the manufacturers recommendations for inspection. The reality is that if you are using the winch line a great deal, it will wear out. that happens.

Splicing/field repair: synthetic rope wins here if you are competent at splicing. This should not be needed as you should: 

1. inspect your winch line in its entirety, 

2. know its capacity (strength), 

3. know the approximate force you are generating, 

4. check the attachment points (at winch and end/hook splice)

5. take care of your winch line. 

Staying on top of these things will prevent winch line failure. That is not to say that winch line failure cannot happen on a 4WD outing and you are dependent on its use to get yourself to safety. If you expect this, learn how to competently splice and use synthetic rope or, carry a backup winch line.

Weight: synthetic rope is significantly lighter that steel cable per ft. when the same MBS is compared. 

Comparison based upon equivalent MBS:

100 ft. of 3/8 inch (0.375 in. or 9.5mm) steel wire rope is approx. 24 lbs. with a 12,000 lbf. MBS

100 ft. of 5/16 inch (0.312 in. or 8mm) synthetic rope (Amsteel Blue) is approx. 2.7 lbs. with a 12,000 lbf. MBS

other figures:

100 ft. of 3/8 inch (0.375 in. or 9.5mm) synthetic rope (Amsteel Blue) is approx. 3.4 lbs. with a 17,500 lbf. MBS

100 ft. of 5/16 inch (0.312 in. or 8mm) steel wire rope is approx. 16 lbs. with a 8-9,000 lbf. MBS

Stored energy and whipping of failed winch line: simply put, do something to protect from this regardless of the winch line in service. To state synthetic rope has no stored energy would defy physics. Once stretched tight, it will store energy in a similar way that steel cable will. Use some form of dampener or just get out of the line of fire. Commercial dampeners are fine, but a personal coat/jacket, prusik/accessory cord with a small weight attached wrapped around the winch line, etc. will reduce the dangerous whip that may occur with winch line failure.

Synthetic rope floats and will not rust.

Synthetic rope is susceptible to UV exposure degradation, steel wire rope is not. If you park your vehicle outdoors and have synthetic rope in your winch, use a winch cover.

In closing, I encourage discussion and the input of those extensively using their winch. I want to learn from those with experience.

I agree with all of that.  But synthetic line is inherently a lot safer because of it's lower weight.  When it breaks it will release the stored energy and come VERY fast at whatever is in its way.  But with less mass flying it will stop easier, so it won't go as far through whatever it hits.  Now if the steel hook on the end of the synthetic line is flying at you it will go a long way through before it stops.  But simply the rope itself won't be carrying as much energy.

As to any issues using a roller fairlead with synthetic rope, I've never really understood that.  The way the side rollers overlap with the horizontal rollers I don't see how the rope can get into the sides of the rollers.  Yes there is a "sharp" corner where the rollers meet. But they don't really meet, so there's really no sharp corner.  Still, other than burrs or nicks on the rollers (which would seem to be an issue if a hawse fairlead had them as well), the corners are the only place I can imagine synthetic rope having a problem.  I just can't imagine what that problem might be.

And by the way, saying "rope" does not distinguish between synthetic rope and wire rope, which is what the hoist / winch industry calls what a lot of people call "cable".

I will never buy another winch with steel cable (for a vehicle).  I have personally seen the damage they do when they break and have cut my hands more times then I can count even with gloves on.  You can also shave about 30-40 lbs of weight going synthetic w/aluminum hawse.

just one comment: safer is actually not a word. either something is safe or it is not safe (unsafe). one could ponder levels of safety which is solely a measure of your comfort level with something hopefully based upon facts and experience. there is way too much erroneous info out there based upon myth(s) that exists regarding this topic.

as oldtime states, he derives satisfaction with working within a 5:1 design factor (the correct term). that is broadly utilized within the rigging, lifting, moving world. this provides a very significant cushion if miscalculations of load, rigging design (sling angles, etc.) and/or friction occur. certainly not a bad way of thinking. 

but personally i think it is a bit high. since i do have a bit of experience in the realm of rigging, i am ok with a 3:1 design factor. fortunately, and in most cases, through careful planning and winching operations with a fairly low mass vehicle such as a flatfender Jeep (minimize your extra stuff on board!) and quality winch/accessories you will not typically even approach exceeding a 5:1 design factor. 

can you? certainly. but why would you intentionally do this?

If you are north of the Mason-Dixon line, there is another potential big problem with synthetic line.  You can't unspool it if it's frozen solid.

That said, I'm also sold on synthetic and I do use it with a roller fairlead.  But I built that fairlead with some really tight clearance between the rollers and used 3/4" 4140 for the shafts to minimize deflection.  I occasionally need a rearward extraction and just run the line under the Willys.  A hawse fairlead would be putting a rather large amount of additional load on the line in that situation.  That is also how I bent my stock Warn lower roller shaft.

Our mind is the tool most effective and the tool most often left unused, or it seems that way often enough.

 Case in point the guy pulling a tree stump in his front yard using a recovery strap (dynamic material) that on the jerk sends the hook through the back window of the Bronco and into the guys head. Right in the middle of a quiet suburban neighborhood no less.

Just think it through, then move forward.