Farmer Boy 5mm Diamond Braid in Knots and Devices

Last updated January 24, 2023.

• Farmer boy
• Diamond braid
• Tagline
• Breaktests

Farmer Boy 5mm diamond braid polyester cord is a commonly used highline tagline in the United States. It is often called Farmer Boy because it is sold by Farmer Boy Ag. It is relatively large diameter, but relatively low strength. The product page lists its tensile strength as both 650 lbs (2.9 kN) and 800 lbs (3.6 kN), although 650 lbs is more accurate given the test results on it. Additional testing showed values of over 900 lbs (4.0 kN), which may indicate the more used seciton tested first was weaker, or strength was suffering more in the figure 8 knots than we had thought. It is often used to tag long highlines, but has also failed on a few highlines.

While at the Paradise highline spot near Durango, Colorado, we performed 40 break tests in Farmer Boy cord in various knots and devices. We focused on common connecting knots like the sheet bend and alpine butterfly bend, as well as toothed and camming progress capture devices. Supplemental testing was done using Balance Community’s break test machine on an additional 16 samples.

The goal of this testing is to give proven values for strength in this cord in common tagging situations. Hopefully it can help in the planning stage of projects, when deciding where Farmer Boy is a good fit to use as tag, and to help calculate safety ratio when able to measure forces while tagging.

Farmer Boy is popular for a number of reasons. First of all, it is quite cheap, with each 300 meter spool costing only $37 USD at the time of writing. It is mostly used as an alternative to 550 paracord. It is about 100 lbs (0.44 kN) stronger than paracord according to its stated tensile strength, and it is roughly 1mm larger in diameter. The extra diameter means it is easier to grab by hand, and performs better in toothed and camming devices not meant for small diameter cord.

Its main disadvantages compared to paracord are its weight (roughly double, although no weight is published for Farmer Boy and I don’t currently have access to a scale to determine its weight) and it’s increased packed size.

The impetus to test Farmer Boy came from our use of it while tagging the US Mile Project at Paradise. Both the walking gap and sight line were tagged first with FPV drones connected to 300 lb (1.3 kN) braided dyneema fishing line. For the sight line gap, the fishing line was used to pull over Farmer Boy directly, and the Farmer Boy was used to pull across the sight line, which was a mix of various cords with windsocks every 30-60m for most of the gap. For the walking gap, the braided fishing line first pulled 450m of 550 paracord to reduce the total weight, then 1 mile of Farmer Boy, which was then used to pull a 6mm pull rope (12 kN, 28 g/m). The pull rope will be used to pull the webbing across.

While the Farmer Boy was pulling in the pull rope, it was first redirected through a high kootenay pulley, down to a cluster of trees, and then through two more trees where it was hauled in by hand. There was a LineScale 2 dynamometer at the first cluster of trees attached to a rollerbiner, then the line went through a Petzl Mini Trax at the next tree, was slightly redirected through a Rollex at the next tree, and finally went through a Petzl Micro Trax at the final tree. Pulling was done caterpillar style between the Rollex and Micro Trax, and behind the Micro Trax. The second progress capture device was used to decrease the amount of force differential carried by the teeth of the first progress capture. The first progress capture was also placed after the first two redirects so the friction in those redirects would decrease the total force seen by the progress capture.

While pulling the pull rope in with the Farmer Boy, the ideal tension read by the dyno was about 0.9 kN, with spikes up to 1.2 kN in wind or when the pull rope wasn’t being released fast enough compared to the pulling speed. The dyno was at a redirect that we estimated to be 30 degrees, which we took to mean the force being read by the dyno was somehwat less than twice the force being seen by the Farmer Boy. We estimated it on site as being 1.5 times the force on the Farmer Boy, but if our angle estimation was correct, it should be closer to 1.9 times the force on the Farmer Boy, giving us a peak of roughly 0.6 kN. Because we were worried about the force in the Mini Trax, and in the handled ascenders used to pass knots, we were not worried about the force change due to the first kootenay redirect. The break test values below show that in both the Mini Trax and the two chained handled ascenders, we had plenty of safety ratio in our forces (roughly 3x safety factor). This shows Farmer Boy can be a suitable intermediary tagline for lines up to 1 mile long, at a price of roughly $200 USD.

The used cord broke consistently around 2.2 kN, which is approximately 75% of its rated strength. Although all of the bends broke at the knot, they broke at roughly 2.0 kN at the lowest, which is roughly 70% of rated strength and 90% of used strength. All of the bends tested seem suitable for use in tagging, although the alpine bend had some minor (but maybe not significant) strength advantage.

Of the toothed and camming devices, the Petzl Mini Trax and CT Roll N Lock did significantly better (1.9kN, roughly 85% of used strength) than the Micro Trax (1.5kN, roughly 70% of used strength) when single wrapped. When doubled, the Mini Trax and Micro Trax both improved significantly. The Mini Trax improved up to 2.0 kN, and the Micro Trax up to 2.15, almost 100% of the used strength. The Roll N Lock actually got slightly worse when double wrapped, breaking at 1.8 kN or roughly 80% of used strength. This seems to be due to a sharp V shape in the cam of the Roll N Lock that can’t accommodate two layers of cord as well. Due to the addition of twists and the increased difficulty of passing knots in double wrapped cords, it appears using a Petzl Mini Trax or CT Roll N Lock single wrapped is the best solution tested for progress capture in this cord.

If a handled ascender needs to be used on Farmer Boy, or it needs to be grabbed inline in some way, chaining two handled ascenders together with a carabiner (through the top of one into the handle of the other) works quite well at about 1.66 kN or 75% of used line strength. Both the Petzl Tibloc and the single handled ascender did the worst in the test, at about 1 kN or 45% of used strength. Chaining two handled ascenders is thus a major benefit if needing pass a knot, although it is not as strong as the best progress captures.

In additional testing the capstan to capstan breaking value was just over 4 kN, indicating either that the cord was weaker at the ends where testing began and it had undergone more use, or that the figures 8s were influencing the breaking values more than had been thought. It is also possible the difference in break test method made up the difference, either through different calibration of the dynamometers or differences in pulling speed.

The Edelrid Spoc (2.33 kN) and Kong Duck (2.44 kN) each performed at near full strength compared to the original 8 to 8 tests. If these results reflect the performance of the devices rather than differences in testing sessions, the Spoc would outperform both the Mini and Micro Traxes, and the Duck would outperform the Roll N Lock. The Ropeman 1 from Wild Country did significantly worse than the other non-toothed camming devices, perhaps indicating the strength tests from this batch were not artifically inflated.

Two other unique progress captures were tested. The first is the CamJam XT from Nite Ize, an aluminum carabiner and progress capture available at very low cost ($16) from many hardware stores. The large version was tested here, which is rated for 1500 lbs (6.67 kN). It says “MAX LOAD 500 LBS” on the side of the device but this is it’s WLL. It broke the cord at 2.74 kN, and in one test the cord broke at the figure 8 before breaking in the cam. This is quite impressive, and suggests Farmer Boy cord and the CamJam XT are a tempting budget option for tagging highlines. It does come with a few drawbacks though. It has no bearings or rolling surface of any kind, meaning pulling with it will be less efficient. Also, the way the device is loaded means the tag can’t be pulled without making a 180 degree turn through the device. Finally, the device isn’t rated for life-bearing use, meaning it should not be used in rescues. Many of the other progress captures are suitable for a light and handy rescue setup, as shown in this video from the ISA.

The other unique progress capture tested was a 4 wrap prusik hitch made of Farmer Boy. The hitch was made of Farmer Boy because friction hitches often work best with matching diameter cord. While this would be a cheap and easy progress capture method, it slipped at 1.26 kN, and continued to slip at under 1 kN until the test was stopped.

The results given below represent the lowest break test from a sample of 3 for each type of test (except for the releasable sheet bend which was tested only once). The lowest tested strength is given rather than the 3 sigma calculated Minimum Breaking Strength (MBS), because of the low sample number, and the fact that tests were completed with a pulley system and on used cord. All of these would contribute to a high variance, giving a deceptively low MBS. It is also questionable whether 3 sigma MBS is appropriate for non life support soft goods.

I believe testing well used cord with a pulley system simulates the real use conditions of this cord well, and should provide a conservative strength figure for the cord in use.

The Kong Duck appears to perform the best of all of the progress captures in 5mm Farmer Boy cord, breaking at 2.44 kN. The Edelrid Spoc is the best of the toothed devices, perhaps due to the smaller channel in the pulley and smaller gap between the pulley and teeth. Both are moderately cheaper than their closest competitors (the Roll N Lock for the Duck, and the Micro Trax for the Spoc). It is possible the high strength values of these devices was skewed by the differences across testing sessions.

It is also worth mentioning that performance of any progress capture will vary significantly between different diameters and constructions of cord, so these results do not generalize to different taglines. Testing of different taglines in these devices is coming soon.

For full break test results, see Farmer Boy Full Break Tests.

I will be trying to keep this page up to date with feedback and new information, and will keep track of edits as I make them here.

1. Added additional break test results and changed discussion to reflect them (10/19/22)
2. Added image from break testing (12/2/22)