Fencing for Rocky or Compacted Ground – Using a Dropper System

I grew up with the mindset that fences had to be fortresses. Rigid and taut as well as non-penetrable was the desired fence in the old days. Then along came high tensile wire and electric fences, and the idea that a fence could act as a psychological barrier (fear of touching it) rather than a physical barrier (unable to penetrate it).

But the greatest benefit of high tensile wire is in its tensile strength – its ability to stretch then return to its initial tension, especially if it’s built with flexible line posts that allow it to react as intended. This tensile strength, combined with its lighter weight compared to traditional wire, meant that line posts could be spread farther apart. Line posts make up a large percentage of your total fencing cost, therefore spacing them farther apart lowers the total fencing cost. And that’s where droppers come in.

Droppers (different from a stay, which doesn’t touch the ground) maintain wire spacing between boss posts on multi-wire high-tensile electric fencing (3+ wires recommended). Droppers simply rest on top of the ground, and their sole purpose is to maintain vertical wire spacings between the line or boss posts. The biggest benefits of a dropper system are:

  • Less Cost. Droppers are a smaller diameter than line posts and cost less than line posts.
  • Easier Installation. Droppers are ideal for areas with tough terrain and in areas with rocky or compacted soils because only the corner assembly and boss posts are driven into the ground, which provides simple and quick installation. Fewer posts in the ground = less work.

Yes, I realize that this concept may be very hard to swallow, let alone to digest. Firstly, we must recognize the fact that an electric fence is a psychological barrier and that the animals fear of the shock they receive from touching it is the actual barrier. They aren’t actually going to push on it, rub on it or even touch it.  This type of fence primarily needs to stand erect and maintain an unabated flow of electric pulses down the fence wires.

One such system that used this technique was the Gallagher Insultimber System. It was actually the norm for electric fences in certain parts of the country. Many people were using it. Insultimber posts were made of a very dense wood product that did not absorb water and was basically an insulated wood post.  Wire was attached with a cotter pin through a drilled hole. This system was discontinued. From my understanding, this was not due to lack of demand, but rather because the source of this wood was basically logged out and no longer available.

Photo Gallery of fences using PasturePro Droppers (click on photo to enter/exit)

 

Steve built his first post & dropper fence several years ago. He built a perimeter fence on some pretty rocky ground during the hottest time of the year. He installed native wooden hedge (Osage Orange) posts at about a 120 foot spacing, then filled in with droppers at about a 20 foot spacing. This fence has 6 strands of high tensile wire.  I inspect this fence every time I go by and it looks great and appears to be working good too. His thoughts on the dropper system:

For years I’d heard about the Insultimber dropper fencing that Gallagher promoted consisting of in-ground posts with stays in between the posts to maintain wire spacing. Having neither built one nor seen one didn’t keep me from judging them as not being as good as a proper fence with all in-ground posts.

However, we kept being told how well our posts would work as droppers. So, we decided to try out a dropper fence on some very steep rocky ground where we needed a new perimeter fence. Though electric fencing is for the most part, a psychological fence, on the perimeters we like to build a fence with hi-tensile woven wire or multi-wire individual wires that would keep stock inside even if the fence was off for weeks. I was somewhat skeptical that a dropper fence would work for this application, but wanted to test our droppers to see how they would perform.

 We have been observing this fence carefully over the past three years, and have been very pleased with the performance of the fence. It looks as tight and sharp today as it did when we installed it, and we’ve found it to be a very effective perimeter fence.

Since that first dropper fence, I’ve built a few more and learned a few things.  In the first dropper fence we built, we used cotter pins to hold the wire to the droppers and we [actually my wife Judy] had to drill 7 holes in every dropper. In the recently built 4 wire fence shown in the video below, the wires were attached with spring clips that hold the wire tight and make attaching the wire a much quicker job. 

Your corner posts and bracing for this system need to be done in the same fashion as you would build any fence, and getting the tension right is really important. In the video below, you’ll notice that the fence swings much more freely than the one above, which can be accounted for by the difference in tension.

A few final things to keep in mind.

  • Droppers won’t work unless you are building two or more wire fences (we recommend at least 3) as they need at least two points of tension to keep them upright and straight. Using droppers that touch the ground every 15-20 feet keeps the wire tight and the height of the fence consistent.
  • The wire attachment at the posts should provide for free travel of the fence wire. However, the fence wire needs to be attached securely to the droppers. Otherwise they will tend to move up or down the fence line. In addition to our cotter pins (which require drilling), we also now have a stainless steel spring clip for attaching wire to droppers. It is a very quick and easy installation and requires no drilling.
  • There is a widespread set of recommendations for the distance between line posts for high tensile wire. I, personally, contend that this depends primarily on terrain and the number of strands of wire. I have friends and customers in the rangeland of the Western USA that commonly go 100 to 150 feet between line posts. As you travel eastward, the spacing’s generally run from 30 to 60 feet. The droppers would generally be every 10-30 feet in between the line posts. But again, you’ll really want to base your spacings on your terrain and fence configuration.

We’d love to hear your thoughts and experiences with dropper fences in the comments below. As always, we’re happy to answer any questions you may have about the system and tell you more about our experiences using them.

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About Gary Duncan

Gary has been active in the fence business for over 15 years. He also raises Highland cattle in a management intensive grazing system and was the first person to market the PasturePro post back in 2005. He enjoys discussing all things grazing and is the main contributor to the blog.
This entry was posted in Fencing Tips, How-tos, Installation, Products. Bookmark the permalink.

11 Responses to Fencing for Rocky or Compacted Ground – Using a Dropper System

  1. avatar Ben Hartwell says:

    First of all I don’t think I’d say that Gallagher discontinued the post/dropper system. they just replaced the eucalyptus/insultimber with fiberglass. Anyone who has gottem a nearly invisible fiberglass splinter knows the disadvantage of this. The big downside of the insultimber system was that the insultimber posts were not strong enough in areas where there could be pressure on the fence like snow banks. Pasture pro seems to fix this problem. The first pasture pro fences I built were with left over insultimber droppers. The only downside I’ve found is that the fence flexes a little too much when I hang a reel on a dropper instead of a post, I usually have to put a temp post on it. I look forward to trying out the Pasture Pro droppers. One thing I really don’t like about a dropper system is a method I’ve seen done by some contractors here. They use small diameter fiberglass rods. With fences that have a bottom wire close to the ground, like sheep/goat fence, I’ve seen many places where the small diameter fiberglass rod penetrates the ground in the spring and the bottom wire has contacted the ground.

    • avatar Gary Duncan says:

      Hi Ben,
      Thank you for your comments.
      Yes you are correct on the eucalyptus/insultimber comment. They did replace that with a fiberglass post & dropper system, but the wooden Insultimber posts are no longer available, to the best of my knowledge.
      I agree with the problems with snow loads. This is a problem in the snow belt and it seems to effect most types of fences.
      The problems usually occur during the spring melting stage, when a huge amount of weight, in ice and snow, begin their downward pressure. Posts are pushed into the ground as well as some of the droppers. This is typical for most line posts.
      I’ve sent Brad Ufen in South Dakota some plates to try out on his posts that get heaving drifting. He will report back to us after this next winter season. –see an early blog: http://www.pasturepro.com/blog/2011/05/snow-loads-and-electric-fences/
      Our droppers have a pretty blunt bottom on them and I dont “think” they will penetrate the ground during the softness of the spring meltdown – but I have been proven wrong before.
      Thanks again for your comments.
      Happy trails & may your fences be hot & true…..

  2. avatar Ben Hartwell says:

    The PP droppers should be fine as far as penetrating wet ground goes, didn’t really have a problem with the insultimber, just these fences I’ve seen with the small (about 3/8″ fiberglass) droppers.

  3. avatar Mike says:

    I am planning about 1600 feet of 6 wire HT fence along a 1 lane county road in the mountains of WV. The ground along the road is rocky and hard with steep drop off that won’t allow straitening the fence, so much of the fence will be on a curve to follow the road up the hill and around the sink holes. fence is to hold goats so I need to stay close to the ground with the bottom wires. To make things worse at least once a year we have cars slide off the road in bad weather, so a flexible fence is important. I am planning to drive locust boss posts at turns with pasture pro post in between. would droppers be a better choice? I will have to have posts to hold wire down in any dips. Also would braking the fence into two runs with wire terminated to a post in the center be better with the curve strain than a single run of wire? Any other ideas for this fence? Thanks.

  4. avatar Gary Duncan says:

    Hi Mike,
    Yes I think that a dropper system would work quite well for this situation. Actually Steve built a 6 strand dropper system a few years ago coming down off a rocky hillside. It has worked very well. I think he went 120′ spacings on the line boss posts, then filled in with PasturePro droppers between.
    You would need to segment the curve with the locust boss posts and as you mentioned, install a boss post at any low points to keep the droppers on the ground.
    I don’t know that I would brake the 1600 feet. You might get more elasticity with one run. High Tensile 12.5 gauge wire will stretch about 2% then return to its initial tension…..in 1600 feet that relates to 32 feet. If you expect cars running into the fence, then braking it into two runs might make potential repairs easier.
    Hope this helps and maybe Steve can chime in with his experiences with his hillside dropper system.
    Gary

  5. avatar Ryan says:

    Hi Gary, haven’t seen many postings from you in a while. I wanted to ask you something about braces in shallow/rocky ground. I am looking to install a woven wire fence in an area that only has 18 to 24 inches of soil over bedrock. There are no trees to use as anchors. Do you have any suggestions for building a brace system that will hold up to the tension?

    • avatar Steve Freeman says:

      Hi Ryan,

      Gary started working for Kencove Farm Fence about a month ago as their Midwest Product Specialist. We at PasturePro are very happy for Gary and know that Kencove feels fortunate to have Gary as part of their team. You can reach Gary by calling Kenocove’s 800 number and asking for him during normal business hours. Kencove is one of PasturePro’s largest customers and we know this is a good fit for all concerned.

      I’ll give you my perspective on your question. I also have the challenge at times of installing cornerposts where ledgerock or limestone is only 20-24″ below ground. Our last large fencing job involved digging approx. 100 corners and on 3 or 4 of them we hit solid limestone the auger couldn’t get through.

      I would probably recommend the floating brace for the areas where you can get down 24″. The concern with a floating brace when the corner isn’t in deep enough is the cornerpost might get jacked out of the ground. You can offset this tendency by using a very long brace pole. Most are installed with a 8′ brace but I found using a 10-11′ brace creates less of an angle, makes a stronger assembly, and helps to keep the post from jacking out of the ground. When installing the corner post I will also drive a bunch of staples in the section of the post that will be below ground to help give it more “bite” as we tamp the soil back in the hole. Because we use hedge posts and don’t have to worry about rot I will use concrete in the hole to help secure it even more. These have held tight through three seasons where we have stretched high tensile woven wire.

      The 18″ depth would concern me much more than the 24″. Here in the Ozarks you will see rock corner posts. These are made by curling a wire cattle panel into a circle and securing the ends together to make a cylinder and placing the cattle panel cylinder where you want a corner. These will be from 4-6′ around. You then fill them with rocks all the way to the top and soon you have a very heavy corner post. These do seem to work and some farmers have a creative side and work at making them “pretty” by using flat rocks to form around the cylinder and then filling them up while some just throw the rocks in every which way! They do work; can’t think of any I’ve ever seen topple. You do need a lot of easy to get to rocks which is not a problem in our neck of the woods.

      The only other suggestion I would have is if you have a post driver available you can sometimes drive heavy walled steel pipe through some of the bedrocks. Here in the Ozarks we are usually hitting limestone and sometimes we can drive a pipe corner into the stone. It does take awhile.

      • avatar Ryan says:

        Hi Steve, thanks for the info. Have you ever tried using duck bill earth anchors?

        • avatar Steve Freeman says:

          Funny you should ask about those. We were recently visiting relatives in central California and saw a large number of vineyards. Many of the vineyards used what I’m assuming were duckbill anchors attached to single corner posts for their trellis’s. The corner posts were driven at a fairly good angle away from the pull of the wire. Several used two anchors for each post, the cables made a V, which I would assume would help keep the post from side motion.
          Kencove sells duckbills and Gripple has a whole kit for anchoring posts http://www.gripple.com/products/catalogue/gripple-anchor.html

          Would sure like to see what you come up with for this situation.

    • avatar JIM YANCY says:

      We put up a 1700 foot section of woven wire on a ridgeline with very thin soil over sandstone. At times only 3 inches of earth before the rock started.
      We rented a 750 cfm diesel air compressor, 300 feet of hose and a rock drill.
      A couple long days saw the line T posts and second part of double H braces well in the ground.
      The starter end posts and direction changes for the guide wire were drilled in with a 110 volt electric jack hammer run off a generator.
      Big boulders, we dynamited to clear the path. Used the rock drill for the blast bores.
      Good experience for young guys. And we lucked out getting 60 foot long X 14 – 18″ used power poles. The bigguns hold great even at shallow depth. 8 years and no adjustments.
      You gotta love rental equipment!
      I am excited to see your comments on the droppers. We spent last summer cutting fence right of ways around some severe property. One 1/2 mile run is going over 30 feet of fill rock, a new dam across a chasim and up steep rocky ground. The droppers will save us a bunch of hassle. Only a 3 wire system for now.
      Thanks,
      Jim

  6. avatar Russ Kassner says:

    Funny you mentioned earth anchors. Out here on the east end of LI,NY we have a lot of vinyards. They ALL us sharply angled end posts anchored with a single guy wire and shallow bar or earth anchor. The wire run is usually several hundred yards under a great tension and supporting a lot of weight. Will look into using this method in my Catskill rocky ground.

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