Kong Hydrobot – Abseiling descender

Back to the Bush Guide

— Tim Vollmer

When it comes to abseiling / rappelling descenders, there’s no shortage of choices available, but for the true canyoning purist nothing beats a carabiner with a couple rusty pitons (despite how dodgy it may look, it is very effective).

The Kong Hydrobot is basically a just a modern, lightweight reinvention of this classic technique. For canyoners this has a number of advantages.

Firstly, you don’t need to remove it to get on and off rope (unlike variations on the figure of 8 or ATC’s). This is particularly handy when you are being pummelled by a waterfall in a deep pool, where cold slippery fingers could end up fumbling your device and sending it down into the void below. Sure, you could finish the canyon using a munter hitch on your caribiner, but that’s hardly ideal!

But better than the old classic, the Hydrobot can be rigged in a range of ways that provide different levels of friction for different rope sizes. It can work with single rope, double rope, or even two ropes of different diameters. I have used it to do a 200m abseil on single 9mm rope, shorter single rope drops, double 9mm rope up to 60m, and even shorter double rope drops on 8mm and even 6mm!

They can also be used as part of an ascending setup (along with a prusik), as well as for belaying or even as part of a hauling system.

One of my Hydrobots, showing some wear after a reasonable amount of action

There are a couple downsides, like with anything. The device heats up on long, dry drops, given it is smaller than many other options such as a rack. Also, you need to know how to add friction mid-descent, as the default rigging will run quite fast on new, dry ropes. The magnetic bar that flips across the middle — taking the brunt of the ropes force — also seems to wear fairly obviously, especially in the sandy canyon environment. That said, I’m yet to have to retire one of my ‘bots due to excessive wear, and they’ve seen plenty of action.

The final downside is that supply and demand seem to have caught up, with the price taking a jump. You’ll now expect to pay about $55 for one — so not the cheapest option — when I’m sure I picked one up for about $35 only a year back.

Still, if you’re after a relatively light, simple, no-nonsense descender which will primarily be used in canyons, you really can’t go past the Hydrobot.


  • Durability / toughness — 4/5
  • Usefulness — 4/5
  • Value for money — 4/5
  • Overall — 4/5

Check out our reviews of some other canyoning gear:

Back to the Bush Guide


14 thoughts on “Kong Hydrobot – Abseiling descender

  1. I’m wondering how reliable they are. I was just using my ‘brand new’ hydrobot from Mountain Equipment to check how comfy my old harness is, and the steel rod fell out! (I’m talking about the steel rod that does down the central spine so that the magnet in the crossbar has something to attract to. The magnet is not attracted to the alloy that makes up the main body of the hydrobot, so without the steel rod in place the magnet does not hold the cross bar shut.) So first question is: what holds the steel rod in place, and how often does it shake loose?

    2nd question for Mountain Equipment: I was a bit uncomfortable buying a hyrdobot from an already opened packet, but assumed it had only been opened for demonstration purposes. So I’m not happy to now notice far more scratches on my bot that one would expect it to get in a shop. Does ME have strict rules about accepting returns of climbing equipment that might have taken a big drop?

    3rd qn: what else can go wrong? I’ve lent my Allen keys to a friend so I can’t check how securely the crossbar is held in position for right-handers. Does the screw ever come loose? Should I use some locktite? (A piton & krab is starting to look more reliable.)

    Other than those problems, the design seems great, but the instruction booklet leaves a lot to be desired. So 4th question: has anyone figured out a best way of incorporating a ‘bot into ascending double ropes?

    • John, I’d take it back. I’ve owned three or four hydrobots, and between everyone I canyon with there’s be dozens of them in use, but I’ve never heard of one having that part come loose. That said, it’s not really a safety issue — the cross bar is held in place by the force of the rope — but it’s still not nice to have something faulty from the start. It also sounds like you’ve been lumped with a returned bit of kit, which is extremely dodgy. I’d put something in writing to their head office and escalate the issue.
      As for the cross bar, I’ve never heard of it coming lose. I also don’t know anyone who modifies it to ensure it stays in place. I do know one or two people who modify the device from right to left handed, despite being right handed, as it stops the rope slipping out when using added friction. I’ve never felt the need to do that.
      The booklet is a bit vague on the instructions. I’ve also found some good techniques for using it based on trial and error. As for ascending, I use it more as a safety backup than a key part of the setup (still use two prusiks, but also run ropes through it in the reverse direction — i.e. as if you are belaying someone — so if the top prusik fails the hydrobot will automatically catch me.) The technique shown in the booklet for single rope should work fine if done for double rope.

  2. Thanks Tim. I took it back to ME and they gave me a new hydrobot. I was relieved to note that all the hydrobots in the shop had the same sort of minute scratching on the crossbar, so I will assume that it is part of Kong’s manufacturing process, and that ME actually follow their policy of no returns on climbing equipment.

    I really like how easy it is to add friction during an abseil with one hand (really handy with an unfamiliar club rope that doesn’t grip as expected), and how easy it is to lock off.

    I’ve looked at Kong’s A4 instruction page a 2nd time, and think I now understand their recommended SRT ascending technique (it is based on the crossbar sliding up to jam the rope), so I will try that on double ropes next time I can. The concept of only needing one prussick loop is quite appealing.

    Thanks for the website – very nice.

  3. Hi have used the bot on short abseil to 40m but on week end 80 m wow ,had problem had to feed rope all the way on single 11mm rope , rope was wet on bottom half , still hard too much friction , others on trip had Pitt stops and racks am no problems , is the hydro bot suitable for long abseiles ?

    • I’ve never used it will 11mm ropes, so can’t speak from experience. I would point out that thicker ropes will run slower with all descenders, and that the longer the abseil the more friction, due to the weight of the rope below you. A rack allows you a greater range of friction settings, but the downside is you can’t change mid descent. If a long thick rope runs well at the top of a long abseil, it will be extremely fast as you reach the bottom. Unlike both a rack and Pitt Stop, the Hydrobot can have friction added lower down. Other than commercial operators, or possibly cavers (where lots of ascending is done) I don’t think you’ll find many 11mm ropes used in canyons these days. Far too much weight and bulk to be practical!

  4. The Hydrobot is good. I used it on an 8 day, 2 canyons a day, trip. The ropes were really sandy and have worn the Hydrobot real badly. The others on the trip used a Rack which did not wear so bad as they are made out of stainless steel. I am thinking I will have to retire it. It has only been used about 10 days!! However, my life is worth more than $60 or so!!

    The wear has created sharp edges along the top entry way. Any rope that crosses over these sharp bits has the potential of cut/wear the rope quickly and badly.

    Has anyone else had this problem?

    Be careful of really sandy/dirty ropes. Yes, the ropes should be clean but when out for 8 days it is not possible to clean them after every canyon.

    • Sandy ropes do cut into the Hydrobot (or any other descender you’re using) quite a bit. It is worth rinsing ropes in a pool as you go, and also being careful to coil them straight out of water rather than from a heap on the sand.
      As for the actual device, it can wear quite a long way before it is a safety issue. If you look at the bar side on you will see this. I agree that sharp edges are more of a concern. That is likely the result of the same sandy rope being used over and over. If you have a range of ropes, with slightly varied diameters, you avoid this. It might be worth simply grinding off the sharp edges so you can get more life out of it.

  5. I would love to see how everybody locks their Hydrobot off. Any pics?

    I’ve only ever really used the Hydrobot. (figure 8 and ATC, briefly a couple of times) and I am very happy with it.

    Some good questions raised here, such as the central bar coming loose. There is a screw there after all.

    • Same here – went to a practice day yesterday and couldnt find a simple way to lock off. Came up with a couple of options but they were fiddly and mightve needed unweighting the rope to release (no good. Would suck to get out prussiks).

    • Phill (and Jason), I generally use the rope around the leg technique. I’m sure rope access people would be horrified, but two or three wraps and you remain completely stationary. And no struggles to unload the prusik! If you do use a prusik to lock off, do it below the descender rather than above, as it takes less load that way and is less likely to stick. The other alternative (and I believe the way recommended by Kong) is to take the ropes through the extra friction section, then over the top, then back through the bottom slot. At this point you will be held stationary, but can then take some extra rope and simply tie an overhand knot or similar to absolutely lock yourself in.

      • I find the Hydrobot not easy to lock off. They are great little devices, simple & light, but i don’t use one (i use a rack) as I find them a bit too fast for my weight (75kg) and difficult to lock off on free-hanging abseils. I have tried various methods of locking off and they do work but very fiddly and what I find the hardest is when you release from the lock-off it’s difficult to have your hand in a position to release slowly

        if anyone has a good method, please let me know

  6. Maybe T2 and Joshua will remember a canyoning trip some time ago when the Hydrobot aided in removing a bolt that I was using as a makeshift plug in my lilo. Pretty versatile the Hydrobot!

    Have a couple myself and have at times used other devices like the Pitt Stop and a Figure 8 – but would not look back now.


Join the conversation. Share your thoughts.

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s