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Fundamental throw lining techniques

Fundamental throw lining techniques

How to set a line in the tree as an arborist

We're going to run through some fundamental throw lining techniques, such as:

  1. How to hand throw your rope up into the tree
  2. Different throw lines
  3. Different throw bag weights
  4. Isolating the high point
  5. Installing a cambium saver
  6. Using a BIG SHOT

Arborist set-up

What you'll need

So first things first is the gear you'll need for setting your ropes in a tree with a throw line.

THROW LINE - Obviously first and foremost, you need a throw line. This is going to ideally be a UHMWPE-type of fibre as it's low friction which is what you want when it's going over unions and tend to have the knots drop out of them, so it doesn't end up tangling up as much. You will also want the throw line to be about 1.5 to 2 mm in diameter (something like Samson Zing It)

THROW BAG - The other things you'll need is a selection of different weight throw bags. Dan uses the Harrison Rockets, which he absolutely loves. From memory, these were the first to come out in the tear drop design.

There are many brands of throw bags and are all essentially similar but the ring size from different brands can differ as can the shape of the bag. A larger ring is more likely to get hooked up over little stubs up in the tree which can be a bit of a pain.

Having a selection of throw weights is really important as the type of tree and shot will depend of what weight you would want to use. For example, a rough bark tree will need a heavier bag. Also a very heavy bag for the opposite end of your line is always useful. 

THROW CUBE - Other than throw bags, you're going to need throw cubes or some way of storing your throw line. Falteimers pretty much have been a staple in the industry for over the last decade. They are fantastic throw cubes. What throw cubes do is store your line and bags so you can pack them down by folding them. This helps prevent your throw line from looping over the top of each other in transit and creating a bird nest of tangles.

It's also a good idea to have at least two throw line setups because eventually, you're going to get one of them stuck and you're going to need the other one to rescue it.

BIG SHOT - Something else that is useful for taking higher shots in the canopy is a Big Shot. Essentially they are two 4 ft poles which connect together with a giant slingshot on the end.

These are a staple in the industry and are fantastic for accessing the higher shots, or shooting the throw bag up there if there's a lot of understory foliage to get through before the high point in the tree. So these are really useful for that and are a great piece of kit.

Throwing knot

The throwing knot

The first and probably the most fundamental way of getting a rope up into the tree is using a throwing knot. This is done by taking your climbing line and making a set of coils that allow you to throw it with weight up into a union and then it uncoils to come down on the opposite side.

Take your rope and form some small coils. What you need to do is work out how much rope it will take to get from the top of the union to the ground. Start by creating a few coils a couple of hand-spans apart. Pinch those coils and wrap around them the bundle. Now pass a bite through this top section and then grab the opposite side.

As well as this bundle, which is going to uncoil when it gets over the other side of the union, you're going to need a few more coils of rope which are going to get the throwing knot up to the union, so it won't pull on this bundle straight away. You will need to estimate of how much rope it's going to take for the rope to get to your union.

Once the coils are set, it's time to throw. Hold the coils in one hand, look at your union and then underhand throw it up and over the union. This may take a few attempts.

Throw bags

Throw bag weights

So something to bear in mind is throw bag weight differences.

Throw bags come in a multitude of different weights, some are 8 ounce (227 g), 10 ounce (284 g), 12 ounce (340 g), 14 ounce (397 g) and so on all the way up to 20 ounce (567 g). Dan tends to throw with a 10 ounce throw bag. If you want to go lighter, what you'll find is an 8 ounce bag will go higher but it has less likelihood of coming back down to the ground if there's a bit of friction up in the union or if you're on a rough bark tree. If you go with the heavier bags, for example a 16 ounce bag, a high shot may end up pulling the opposite side of your line and you could lose it up the tree. So you want to have a heavy bag on the other side of your line to prevent this from happening.

How to attach a throw bag to your throw line

Simply pass the throw line through the top ring and do a few wraps around the standing leg of line. Then pass a bite through the loop at the bottom and then cinch that down to create a slip knot at the bottom. So that when it comes to removing the bag, it's easy to pull that tail and pop the knot off.

Setting a throw line

Throwing a throw bag into the tree

To throw the throwing line, you're going to use a pendulum-like motion to generate a bit of momentum and you want to keep tension in the throw line at all times - don't let it hop or jump. And there's a few different ways of doing this.

  1. Number one is to pass a bite of rope through the ring and then find your ideal length and you can throw it between your legs and line up exactly where the union is and let go with both hands.
  2. The second way is doing exactly the same - pass a bite of the throw line through the ring but hold it in a single hand throw. This is more Dan's style. When you release it, the bite pops out.
  3. But Dan's personal way of using a throw line is hanging the throw bag down at hip point, tie a Marlinspike slip knot and then hold on to the knot and use this knot as a pendulum. Because it's a slip knot, it will pop out by the time it gets up to the tree.

Isolating the high point

After you've gotten your high point with your throw line, the next thing you do, before you pull your rope up there, is work out if you need to isolate the high point. If we were literally climbing this with an SRT base anchor, we wouldn't need to isolate it and we can just pull our rope all the way up over the top union and then it wouldn't matter that it's going down through some other branches but the ideal situation, if you're climbing double rope or even a lot of SRT applications, is to choke your high point and to do that we need to isolate it beforehand.

So there's a few different ways to isolate your high point. You can pull your throw bag up there with a bit of a pendulum swing into it and then get it to pop over any of the lower limbs which you don't want it over. The other way is to connect another throw line to this throw bag and then as it gets up there use the other throw line to pull a movement into the throw bag and then get it to drop down the other side of the limb. The easiest way though (because we've got another throw bag on the opposite side of this throw line) is just to pull up the opposite side of the throw line and get it to drop down this side instead.

Once your high point is isolated, you can pull the rope up.

Attaching the climbing rope to the throw line

Setting the climbing line

With Harrison Rockets and a lot of other throw bags, they've got this loop at the bottom which you can clip an accessory carabiner to. And if you've got a splice in the end of your climbing line, obviously these can quite simply just clip together and you can pull this up and over the limb. If you don't have a splice in the end of your rope or you don't have this attachment point on the bottom of your throw bag, there's another way to do it.

What you're going to do is take your rope, tie a clove hitch in the throw line and thread this onto the rope (maybe 50 cm (a foot or two foot) down your rope) and then just keep tying half hitches as it goes up towards the end of the rope. This pulls the rope in line over the top of the union and helps minimise the chance of things getting stuck. So we're going to use this method to pull the rope up the tree.

Now you have a nicely isolated high point with the rope not getting stuck as you pull it up and over the union.

Cambium saver

Installing a cambium saver

Alternatively, you may want to install a cambium saver. For example, if you're running double rope technique on an isolated union up there, you may want to remotely install a cambium saver.

Take your throw line, which is isolated over the limb, and you're going to take the small ring side of the cambium saver, install the throw line through the small ring and then tie your throw bag back on. Then we're going to pull a little bit of tension into the line and on the big ring side of the cambium saver, clip it onto the other side of the throw line. So what this is going to do is flip the small ring over the limb and then it's going to descend the throw line back down running through the cambium saver for you to install the rope next.

Big shot

Using a Big Shot

After assembling the Big Shot, put the throw bag into the pouch and when you go to launch it you're going to put the bands on the opposite side of the pole to you because if a band breaks, hopefully it's not going to come come back and hit you in the face or in the head. The Big Shots are best used with a trigger setup but can be used manually as well.

When you pull down on the pouch, it's a good situation to kind of just pinch the bag down into it to hopefully hold it in place. Because you don't want to get to the bottom of your pull and then have the throw bag drop out.


So we've gone over a few fundamental pieces of information when it comes to throw lining. First and foremost just getting a rope into the tree if you don't have a throw line, then going through different throw weights which you might want to use and why, how to attach a throw line onto your throw bags, and then different throwing techniques for getting them up into the tree, isolating the union, and then installing a rope up and over the union. As well as using a cambium saver and a Big Shot.

So, if you're new in the industry, hopefully, that's a good bit of information to help you out and get you started.

Enjoy and share with your mates if this was useful. Cheers.

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