The arborist throw line is an invaluable field radio kit tool

Two days ago, I activated Parc national des Grands-Jardins (VE-0499)–a stunning national park here in the Charlevoix region of Québec, Canada.

As soon as we drove up to the activation site I had researched in advance, I surveyed the picnic area and mentally noted the best spot to deploy an end-fed half-wave using my trusty arborist throw line.

With the throw line’s assistance, I had an antenna deployed within a couple of minutes max.

It hit me then just how invaluable a tool the arborist throw line has become for the types of park and summit activations I do.

Pre-Throw Line Activations

During NPOTA (National Parks On The Air) in 2016, I wasn’t aware of arborist throw lines and had been using some high test monofilament fishing line attached to a weight.

The fishing line was strong enough to support my QRP antennas and I could typically reuse the same length of line for 2-3 activations. Eventually, the line stretches and weakens thus it must be cut off and discarded.

Never again

I’m a big Leave No Trace kind of guy, so am embarrassed to admit that during one activation, my fishing line snagged high up in a tree and left a bundle of broken monofilament in a spot where I could not retrieve it. This was deep in a forest and although I doubt anyone will ever see it, I know it’s there. It bugs me to this day and if I ever sort out a way to remove it, I certainly will.

This occurrence was one of the catalysts for purchasing my first arborist throw line kit.

That throw line kit absolutely revolutionized my antenna deployments by:

  • increasing the speed deployment,
  • increasing accuracy,
  • allowing me to re-use the same line hundreds of times,
  • and being orders of magnitude more reliable and stronger than fishing line.

It changed everything and I’ve never looked back.

Since that first throw line kit (which I’ve lent to a newly-minted active ham), I’ve built four more throw line kits.

Compact Weaver Throw Bag

In early 2021, I purchased a second throw line and 12oz weight (identical to my first) for backpacking along with this compact Weaver Leather throw line storage bag (affiliate links).

I was searching for a more SOTA-friendly/backpack-able solution than the arborist throw line cube.

I was very skeptical about how easily this bag would work in the field. One of the reasons my throw line storage cube works so well is because the opening is large allowing the line to deploy without tangling. Packing up is fast because the line can be flaked back into the cube in a matter of seconds.

After taking delivery, I did a full break-in of the new throw line (attaching it to a tree, stretching it to full length, then pulling it for enough tension that some of the bend “memory” was removed). Then I attempted to simply stuff the line in my throw bag–it took ages, because the whole idea of a throw line is that it doesn’t easily tangle. The line wanted to “spring” from the bag as I tried stuffing it in. (I believe it was Scott KN3A described it as “trying to stuff a snakes in a bag”–!).

Then Mark (NW3S) gave me a simple tip: when stuffing the line back in the bag, wind it on your hand using the figure 8 method. 

In short, this works beautifully. Not only can I re-stuff the bag in very short order, but the line never tangles when I deploy it during my next activation.

I made a short video showing how to use the figure 8 method:

This small throw bag worked so well, I started using it for nearly all of my activations.

Then I learned about an even thinner, more compact throw line.

Ultra-Compact Marlow/Tom Bihn Throw Line Kit

In November 2021, Mike (W4MAF), suggested I check out  Marlow KF1050 Excel 2mm marine/arborist line. He’d mentioned that he’d had excellent experiences using it in the field. It’s much thinner than the yellow Weaver poly line I’d been using.

Marlow KF1050 Excel 2mm marine line is sold in 50 meter reels; I purchase mine from WesSpur (an excellent arborist product retailer).  I quickly realized that a Weaver throw bag was way too large for this line, but fortunately I had a spareTom Bihn Small Travel Tray which works perfectly.

Although the Marlow line is slightly more prone to tangle out of the bag because it’s not as “springy” as the bulkier Weaver line, and it can pick up little twigs and leaves off the forest floor when packing it up, it works beautifully.

In fact, it has become my default throw line since I first started using it in November 2021.

It’s so darn compact, you don’t even notice it in your backpack.

When I purchase a reel of 50 meters, I cut it in half to produce two 25 meter sections.

I find that 25 meters is more than enough line for all of my SOTA activations and the majority of my park activations. It’s so compact, I can actually store it on my MTR-3B Field Radio Kit:

Twenty five meters of 2mm line is so easy to wind on your hand, it’s not even necessary to keep a throw line bag to store it. Simply deploy the entire length each time, wind it back up in one go on your hand, and use a Velcro strap to hold it together.

Watch the first portion of this activation video for an in-depth look at my 2mm throw line kit:

Throw line fears

Over the past two years, I’ve heard from fellow friends, activators, subscribers, and readers who are reluctant to use an arborist throw line. Typically, they cite the following concerns:

  • A line, throw weight, and bag will typically set you back $45-55 USD.
  • Fear it will permanently snag in a tree
  • Concerns that it’s too conspicuous when deployed

It’s true that proper arborist line and throw weights are pricier than fishing line, string, etc. That said, I believe it’s an investment that will last for years.

Some have told me they’re willing to pay for the line, but the throw line weights are too expensive.  Trust me: buy the highest quality throw line weights you can afford. The cheap ones are known to eventually bust when they hit the ground too hard.

And trying to use (as I used to) a heavy steel nut or rock? Think about what you’d rather have ricochet and hit your head or a nearby car: a heavy yet soft throw line weight, or a steel nut? Trust me: it’s worth the investment.

Side note: speaking of throw weights, I primarily use 8 and 10 oz weights with the 2mm line. With the thicker yellow Weaver line, I use 10 or 12 oz weights. I feel 16 oz weights are a bit too heavy if you want to launch a line high in a tree.

In the hundreds of deployments I’ve done with arborist throw lines, I’ve never had one come close to snagging in a tree. If this worries you, just avoid areas that are super dense with tree branches. Those are the spots most likely to snag a line.

In terms of throw lines being conspicuous, I actually think that’s not a bad thing. If operating alone in a park, you need to make your wire antenna deployment conspicuous if there’s any possibility of someone unknowingly walking through the middle of it. I bring flagging tape for those rare circumstances. You may also see that I use my high visibility throw line to encircle any trip points.

Of course, arborist lines can be stealthy as I learned only recently.

Paracord ≠ Arborist Throw Line

It might look like throw line, but it isn’t.

I’ve received a couple of messages from readers who’ve complained that their throw line is useless because of how difficult it is to deploy, how easily it tangles, and how it gets stuck in trees.

In both cases, I discovered that these ops were actually using paracord instead of arborist throw line.

Throw line is specifically designed for arborists and has a jacket that doesn’t easily tangle in trees. It reliably glides through branches despite rough tree barks you might encounter.

While I love paracord for supporting my permanent wire antennas or heavy field antennas–it’s super durable and useful–it is a poor choice as a throw line. Paracord’s jacket may feel smooth to the touch, but it actually grabs tree bark and creates fiction. Arborist line doesn’t do this.

Always use throw line that’s available from an arborist supplier/retailer and you’ll never be disappointed.


If you live in a part of the world with lots of trees and you’re a devoted park and/or summit activator who uses wire antennas, you really need to consider adding an arborist throw line to your field radio kit.

All of the throw lines I’ve mentioned above work well: choose one that fits your style of field radio work. If you’re not into backpacking, then consider the full folding cube option. If you’re into SOTA, go with one of the compact options.

I promise: you’ll consider a throw line kit one of the best purchases you’ve ever made to support your field radio addiction!

19 thoughts on “The arborist throw line is an invaluable field radio kit tool”

  1. Totally agree on your point of just going ahead and buying a proper line and weight; I started out with improv. items and wish I’d just saved myself the hassle from the get-go.

  2. I have 2 throw lines, on complete with 16 oz weight and a 2nd I bought the 16 oz weight and added my own line.

    I do not use fishing line, but small rope. This way I can throw up the line over a tree, remove the weight and tie on my End Fed Wire and pull it up. Using the rope saves time and works well.

    Only problem I often find at parks there is no tree in the right location. So I bring my 20ft portable flag pole with ground stake and use for the high end of the End Fed allowing me to face the antenna in the direction I need. Last time I attached the pole to a chain link fence that surrounded the play ground.

    73, ron, n9ee

  3. Thank you for the article. Having just got theArborist throw line I was having problems with storage. Thanks for the suggestion of the figure 8 wind up.

  4. Thanks for this thorough overview. I’ve been refining the old slingshot launcher for years now and have honed it to a fine edge, but I’m interested in the arborist route for three main reasons: it’s cheaper, it’s more compact, and nobody can accuse you of using a “weapon”. (This hasn’t happened to me yet, but given the tenor of the times, I think it’s inevitable.)

    The good thing about the launcher is that once you master it, you can hang your antenna very high, which is great when using a wild wire. Of course, few hams do that now, and great height is superfluous when using a pruned EFHWA

    Anyway, for those reasons I’ve been looking into the arborist line. Good to hear you’ve had good luck with it. Thanks for the information! I’ve saved it to my bookmarks.

  5. Thanks for the figure-eight tip! Re-stuffing the bag was the only part of using the arborist kit that was less than perfect. I use an 8oz Weaver weight and line in the Tom Bihn tray and they work great.

  6. So much to take away from this post! Will reread it again. I’ve been to the Saguenay but never to the Charlevoix region. Definitely on my bucket list! The most likely impact of leaving the fishing line is on small birds. Hopefully the sun will have destroyed the remains of the line you couldn’t retrieve.

    1. I copied your setup including Tom Bihn travel tray. At the time I could only find a 12oz weight. I’ll probably by an 8oz and I think it may be perfect. Love how compact this setup is

  7. Excellent primer on arborist throw lines for antenna deployment! I use this tool and technique in nearly all my activations in Pennsylvania parks.

    One thing I have been doing lately is to leave the throw bag attached to the end of the line when hoisting the antenna. The bag gives enough weight to overcome line friction when bringing the antenna down for retrieval for using links to change resonant length. Wire is so light that I’ve had to pull on the antenna to lower it, and I prefer to avoid tugging on the wire.

    73 de Brian – K3ES

    1. Brian, I’m trying to picture what you’re doing. Very short throw line or really tall trees and an excellent arm?

      My weight, on the end of a 75′ 1.75mm “Lash-It!” line hits the ground on the other side of the tree and its job is done. I take it off before pulling the antenna up and over. For retrieval, I pull it back from the radio side.

      Anyway, curious to learn a different technique.

  8. Had mine for only a few weeks now, so any hints and tips on deploying are gratefully received. Initial reaction was how easy it really is. Tried lots of things in the past without the accuracy of a proper throw line. Thanks for sharing

    73 de M0AZE


  9. How well would the 2 mm Marlow line work with a golf ball and slingshot? We’ve got some pretty tall trees here in the Pacific Northwe(s)t and I’d like to be able to get antennas up higher than my 87 year old arm can do unaided.

    David VE7EZM and AF7BZ

  10. Whoever taught you the figure 8 winding method may have had it passed down to him from a teletype tape operator. That’s how we did it in the military. Some poor soul had to be running around servicing messed up messages. Invariably they would have several tapes strung over their neck. Thus the nickname for the MOS (Military Occupationa Specialty)-
    tape ape! Thanks for the post Tom.

  11. Have you heard of anyone having a problem with park rangers complaining about putting antennas into trees? I’ve only done POTA activations with a fiberglass pole / vertical antenna because of comments that I’ve read about not being able to do that. I’d love to go lighter weight and just use a wire in a tree but wouldn’t want to waste a trip and lose out on an activation.


    1. It’s incredibly rare in North Carolina to *not* be allowed to put wires in trees at a state or national park. The main exceptions are those parks with historical or archaeological significance. Or perhaps in the view shed of a site or scene.

      I have heard that some states are much more restrictive.

      If interested in a particular park, go to the park activity page on the POTA site and write to a few activators asking about their experience at a particular park. That’ll likely give you more insight than anything else.


  12. An excellent article. Once you try a proper throw line you’ll never go back to other methods. I bought the Weaver medium bag because I was afraid I wouldn’t be able to make the small bag work for me. Thanks for the tips, I guess I’ll have to order a small one now. (Although I seldom set up very far from my car or truck so the size of the bag isn’t really an issue for me.) I absolutely agree on not using other types of cord (paracord, seine twine, etc.) with one exception: for a super small and lightweight solution I have been using Atwood 1.18 mm micro paracord with a four ounce lead weight. It is slick enough to pass over limbs and leaves and has never tangled on me (yet). I keep it on a spool and fake it down on the ground before throwing.
    If you will indulge a small pedantic rant: sailors have been FAKING DOWN line for centuries. I think “flake” is a modern perversion of the term.

  13. Hi Thomas, just a quick note: I ended up purchasing the Weaver kit (12 oz weight and line/red bag). I’m not sure why I was hesitant to use a throw line, but it is absolutely amazing. It’s so simple and easy to get a line 30-40 feet into the smallish trees of Oklahoma, and has completely transformed how I look at field operations. The added side effect, though, is that is now I study every tree I see I for suitability to hang an antenna whether I’m in the field or not! Thanks for the detailed post. – Sam WN5C

    1. Lash-It is the same line as Zing-It, but marketed for boating use and recommended for stealthier hams. The only difference is the less visible gray color. I’ve never had any trouble seeing it a tree, but it’s not attracting attention.

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