Welcome! This guide aims to facilitate new international ASAC members in learning outdoor single pitch lead climbing (Outdoor Voorklimmen Singlepitch; OVS for short) climbing techniques. ASAC is an Amsterdam-based student climbing organisation. This website can also be used by other would-be outdoor climbers to learn about outdoor single pitch climbing techniques, however, ASAC is referenced throughout this guide. The techniques that are described in this guide will enable you to safely and independently sport climb outside on single-pitch routes. This guide assumes you already have your indoor lead climbing certification or equivalent.

This guide alone will not teach you to climb outside safely and independently. It is not a replacement for practice and training. You will need to practice by yourself and with more experienced people, for example during an ASAC climbing weekend, during one of the OVS course introduction evenings organised by ASAC or with ASAC members who already have their OVS.

The contents of this document are peer-reviewed by several experienced outdoor climbers. Everyone who contributed to this document was a member of the ASAC at the time of writing. Although many elements of this document are inspired by the official guide, we have made a lot of changes and additions that we believe to be of great utility for those wanting to learn single pitch lead climbing and belaying. Please note that there are several alternative ways of performing the techniques that are described in this guide. The techniques described in this guide follow the principles and techniques as determined by ASAC.

This document aims to be a comprehensive, instructional, but optional and community-based source of information. This guide primarily focuses on outdoor climbing, including single pitch lead climbing outside, as well as various other aspects of the sport that the author believes to be essential to performing this sport safely and pleasantly. It covers all the important techniques and knowledge that ASAC climbers will need for their OVS exam.

⚠️️Use this guide at your own risk. DO NOT go climbing outside alone without someone who has at least done their OVS exam or (international) equivalent. DO NOT overestimate your capabilities. Climbing is dangerous. Weigh the risks carefully before proceeding!

2. Introduction

By using OVS techniques you will be able to climb single-pitches outdoors safely and independently. Before learning the techniques in this guide you should already know how to lead climb indoors and be familiar with all associated safety measures, for example by doing a certified IV (Indoor Voorklimmen) course at a Dutch climbing gym. Currently the ASAC organises a course for learning OVS techniques, as well as OVS evenings which offer a quick insight into the most essential techniques. Even if you are doing a course, it is important to realise that you yourself are primarily responsible for your own learning process.

Safety hazards and extra info:
Further on in the guide, we’ve marked safety hazards and safety-related explanations and extra useful information and tips with the following symbols :

Safety hazards and explanations are marked with a ⚠️ and are displayed in bold.
Extra information and tips are marked with a 💡.

OVS exam
When you feel that you are proficient in all the techniques and knowledge displayed in this guide you can take the OVS-exam during an official ASAC climbing weekend. When there are enough instructors available you will then spend the day with a certified climbing instructor in order to demonstrate for them all the relevant techniques. They will then judge whether you are able to climb safely and independently outside and grant you the OVS status by vouching for you. After that you will be able to receive an ‘OVS licence’ from the NKBV through the Opleidingscommissie (opleiding@asac.nl).

Your climbing career after OVS

After you get your OVS licence you can continue with other courses such as the OVM (multi-pitch) course or the traditional climbing (OVT) course. You can opt to become a certified instructor for through ASAC or NKBV after successfully achieving your OVS licence. You can also become an instructor for multi-pitch and/or traditional climbing after finishing these respective courses. You can contact the Opleidingscommissie (opleiding@asac.nl) for more information on how to become an instructor. There's also a good article on becoming an instructor over at the ESAC website (weblink).

3. Ethics concerning climbing outside

A lot of climbing areas have been closed due to the negative impact of climbing and climbers. This section of the guide focuses on ethics, how to behave, and laws concerning climbing.

Inform yourself on the principles of Leave No Trace
Education is the most effective and least resource intensive solution to land protection. The seven principles of Leave No Trace have been developed especially for this purpose.

Plan ahead and prepare (weblink)
Travel and camp on durable surfaces (weblink)
Dispose of waste properly (weblink)
Leave what you find (weblink)
Minimise campfire impacts (weblink)
Respect wildlife (weblink)
Be considerate of others (weblink)

Nature preservation areas
A lot of European climbing areas are situated in protected nature areas (Natura 2000). For these areas there are strict rules in place to protect nature. Inform yourself on the situation, rules and regulations for the climbing area you are visiting. You can do this by checking the guidebook of the area, the website of the NKBV, the KBF, or other climbing and/or nature organisations. You can also ask local climbers in the area or on social media on the do’s and don’ts of the area. Always check whether there are any area closures in place, for example due to breeding birds.

Respect flora and fauna
The rocks are also the homes and breeding place of animals, such as birds, bats and lizards, and plants, such as trees, endangered flowers, mosses and lichens. Be respectful and considerate of this environment. Do not climb on rocks with breeding birds (rapture season- this is usually indicated on a sign at the entrance of the climbing area). Do not remove any plants or mosses from the rocks without talking to someone who’s knowledgeable of the nature in the area.

Be mindful of going to the toilet in the outdoors
Always go to the toilet before climbing. Of course, when nature calls, you have to go anyway. If there’s an eco-toilet in the area, go there. If there isn’t, it is always best to pack out your faecal waste and toilet paper whenever possible (for example in a plastic bag) (video). Digging a hole about 15-20 cm deep and away from any water sources is the next best solution (a garden trowel can be useful). Do not poop under overhangs or in caves, because then it is not possible for the rain to wash your waste away. If you're going to bury paper, it is better to use single ply (cheaper) toilet paper than the multi-ply stuff.

Waste and litter
The next standard is less complicated: do not litter. Take your own litter with you and also pick up other litter that you may encounter.

Wet rock
Please refrain from climbing on wet rock surfaces and speak up when others are. Doing so not only increases the risk of slipping and falling due to the slippery conditions but also accelerates the erosion of the rock. Certain high-porosity rock types, like sandstone (e.g. Pfalz, Berdorf, Fontainebleau), limestone (e.g. Freyr, Grands Malades) and dolomite (e.g. Dave, Porche de Roiseux) , tend to absorb water, weakening hand- and footholds and making them more prone to breaking. Additionally, moist rock polishes faster, resulting in persistently slippery conditions even when dry, which ultimately diminishes the climbing experience for future generations. On the other hand, low porosity rocks such as slate, schist, quartzite, granite, basalt, and diorite are safer options for climbing when wet. Please inform yourself of the rock type when considering a climbing trip with questionable conditions.

Clean climbing shoes
Make sure your climbing shoes are clean before getting on the rock! This not only prevents nasty foot slips but is also very important to prevent erosion of the rock i.e. slippery rock. Resole your shoes before they’re too worn out in order to get the most life out of your shoes. You can have your shoes resoled at Schoenmaker Hillie’s (near USC) your local shoe maker, https://www.soescalade.nl/, https://www.cambreur.nl/, or https://www.snijderwerk.nl/. When you’ve been outside and are back in the gym, it is nice to clean any dirt off your shoes before going back to plastic. Do not climb in approach shoes unless the sole is absolutely squeaky clean.

Magnesium (chalk)
Avoid excessive use of chalk. Brush off any excessively chalked or rubbered holds and/or tick marks. Preferably use water based liquid chalk if you can. Using no chalk at all is not recommended (and seen as disrespectful by some) because it’ll generally leave holds greasier, grimier and sweatier than necessary. If you have very sweaty hands (or maybe even hyperhidrosis) we would also recommend using an antiperspirant to counter this (e.g. Rhyno, Odorex, Antihydral). However, in some climbing areas the use of chalk is prohibited.

Sunscreen
Do not climb with (remnants of) sunscreen on your palms and fingertips. Nobody likes to climb on greasy holds! So always wash your hands after applying sunscreen.

Noise, sounds and music
Be mindful of the sounds and noise you make in and around climbing areas. Cursing, screaming, being obnoxiously loud and playing music is generally considered disrespectful by others. This also includes elaborate and unnecessary communication between the climber and the belayer. If you want to play music, it is good etiquette to ask other people at the crag if they mind you doing so. In some (nature protection) areas it is not allowed at all.

Sharing beta
Some people want beta (description on how to climb a route), some people don’t. Always be mindful before you start shouting beta at someone. It’s recommended to ask someone politely if they would like to get some beta.

Parking
Only park where you are allowed to. There is lots of information to be found online or in the local guidebook on where to park for the specific climbing area that you want to go to. Even when a more convenient spot seems available, follow the instructions in the guidebook, because random parking often causes a lot of frustration with local villagers. Always make sure authorities and land managers can access (service) roads.

Stay on the obvious (prepared) trails, do not go off-trail
Erosion is real and can be disastrous for the local environment.

Private Land
Do not walk over/through/on private land without permission from the land owner.

Fire
Do not make open fire in areas about which you are not absolutely sure that you are allowed to.

Wild camping and ‘van life’
In most places in Europe, wild camping is not allowed. Even in areas like Fontainebleau where everyone seems to live in the parking spot, it is not allowed! It is a surefire way to eventually get climbers and climbing permanently banned from the area. Support the local economy by visiting the local campsite instead.

Friendliness and manners
Be friendly and say ‘hi 😀’ to other climbers, recreationists and to the locals. Act like an ambassador for the sport to people or locals who might not be familiar with climbing.

Sharing the crag
You will often encounter other climbers at the crag. When we are considerate, this is one of the delights of our sport. When we claim too much space at the crag, it can quickly turn into an annoyance or even into conflict. That is why it is good to live by a few principles:

When you keep clear and respectful communication going, there are ways to share a route with others, even when there are several people who are interested in it. For example, create a ‘line’ that people can join. This way everyone knows how much longer it will take and can wait for their turn. On a busy day, try not to hang on the route for too long. What is ‘too long’ has to be judged on a case by case basis.
Do not claim a route by putting up a toprope any longer than necessary, other people might want to climb it too.
When your project is a popular route on a given day, consider not spending too much time hanging in the rope to figure out the moves. Of course, if for example it is your last day, you can always ask whether the other people mind if you take your time on it. Perhaps for them it is just going to be a warm-up or a random route that they don’t mind finding a substitute for.
If you desire to leave your draws on the route for another go after your buddy works a different route, be mindful and see if anyone else is looking to climb that route. If someone comes up, offer them to use your draws or take them down. Leaving in your draws is not a way to ‘claim’ the route. When you lower, your turn is over and the next person should be able to climb - with or without your draws.

Support the local economy
We want climbing to have a positive impact on the local economy and inhabitants. Let this motivate you to visit the local bars, restaurants and cafés after or before climbing. This way we make sure the local people feel they have something to gain from preserving or even promoting climbing in their area.

Climbing in Belgium
To climb in Belgium you need a ‘klimjaarkaart’. This climbing pass is valid for a year. It gives you access to 32 climbing areas in Belgium and allows you to contribute to the conservation and maintenance of those climbing areas. You can buy this pass from the NKBV.

Join the Dutch Rebolting Team (DRT)
You can contribute to the maintenance and safety of the climbing areas in Belgium by volunteering for the DRT (more information here - in Dutch).

4. OVS Materials needed

This section contains a list of the necessary equipment for completing OVS. Please see the articles in the next section for more explanation on some of the gear mentioned.

Absolutely necessary equipment for OVS, please note that you can borrow a lot of the listed equipment from ASAC:

Helmet (i.e. rated for climbing) (‘klimhelm’) (1 x)
Climbing harness (‘klimgordel’) (1 x)
A pair of climbing shoes (‘klimschoenen’) (1 x)
ATC belay device or equivalent that can be used with two rope strands (‘zekerapparaat’) (1 x) - get an ATC guide if you want to continue with OVM after you’ve achieved OVS. Other devices such as the Petzl GriGri or Mammut Smart also work fine for general outdoor climbing, but you’ll need an ATC for your OVS exam.
Belay-specific carabiner (‘safe-biner’) (1 x) - a carabiner which requires three or more actions to open. Examples of belay-specific carabiners are the DMM Belay-Master or the Black Diamond Gridlock.
Locking carabiner (‘karabiner’) (2 x)
6 mm diameter climbing-specific cord, 1 meter length (Prusik cord, ‘Prusiktouw’) (1 x)
120 cm climbing sling (‘sling’) (1 x)
Personal Anchoring System (PAS) / Lifeline (‘zelfzekering’) (1 x) - see section 5.5.
Quickdraws (‘setjes’) (10/12 x, or 6 if you share with a partner)
‘Single’ climbing rope (‘enkeltouw’) 60/70/80 m (1 x)

Also necessary (for ASAC weekends):

A valid NKBV membership;
A valid travel insurance ‘reisverzekering’ that covers outdoor climbing from the NKBV or equivalent;
A valid Klimjaarkaart (for climbing in Belgium).

Optional and/or recommended equipment (in no particular order):

Rope bag (‘touwtas’) (1 x)
Belay glasses (‘zekerbril’) (1 x)
Belay gloves (‘handschoenen’) (1 pair)
Crack gloves (‘crack handschoenen’) (1 pair)
First aid kit (‘EHBO-kit’)
Climbers tape (‘tape’)
Hiking shoes (‘wandelschoenen’) (1 pair)
Chalk bag (‘pofzak’) (1 x)
Brush (‘borstel’) (1 x)
Head torch (‘hoofdlamp’) (1 x)
Guidebook of the climbing area (‘topo’) (1 x)

5. OVS Materials guide

In this guide we skip the materials that you already should have knowledge about (specifically belay devices and harnesses) for efficiency reasons. I do cover all the essential ‘new’ information you should know for OVS specifically on materials such as climbing rope, quickdraws, cord (Prusik), slings, carabiners, Personal Anchoring Systems, helmets, bolts and anchors. Some parts of the texts underneath mention certain techniques, terms or use cases. Don’t be intimidated or worried by this, not everything will make sense the first time you read it. For now just read it, and revisit this section later.

⚠️️ Please make sure you read the manual on all your climbing materials before usage, please use the materials according to the manufacturer's description, and please be aware of your materials' lifespan as described by the manufacturer. Routinely check all your gear for wear and tear.

5.1. Climbing rope

Climbing rope ('klimtouw') is rope that is specifically made for and rated for climbing use. For single-pitch climbing you should use a ‘single rope’ (‘enkeltouw’). This means the rope is certified (UIAA 101 and/or EN 892) to be used as a single strand when climbing. You should know that ropes used for climbing are ‘dynamic’, i.e. the rope can stretch, in contrast to a ‘static’ rope that barely stretches. The stretchiness of the rope helps to absorb impact forces during climbing falls. Climbing rope is made of polyamides (nylon). It consists of an inner core (the part that absorbs most of the forces)) and an outer sheath that protects the core strands of the rope.

Climbing rope is twisted from core strands and wrapped in a protective and colourful sheath (credit: TENDON).

⚠️️ General safety points:

Before lead climbing, always make sure the rope is long enough for the route: a 60 m rope only works for routes up to 30 m, a 70 m rope allows you to climb up to 35 m, et cetera.
Before lead climbing, always make sure the rope is laying ‘bottom-top’. You can do this by running through the rope from bottom to top. While doing this, you should check the rope for any damage, especially on the first climb of the day. After you’ve finished running through the rope, the leaders’ side of the rope is the top of the rope stack. By doing this the belayer won’t have to deal with knots in the rope while giving out rope to the lead climber.
Before lead climbing, always make sure the bottom of the rope is tied off with a knot that can’t pass through the belay device. You can use a barrel knot, a stopper knot, an eight on a bight or a rethreaded eight for this purpose; make sure to leave at least 1 metre of tail after the knot. If you have a rope bag, you can tie the rope to the rope bag using a rethreaded eight.
Always keep your rope as clean as possible and always check your rope before climbing. Remove small debris from your rope bag before you pack your rope in after climbing. A dirty rope wears much faster than a clean rope.
Beware of cutting your rope by friction on rough surfaces during climbing, especially during top roping. A rope can be cut if it slides along a sharp piece of rock. Try to prevent this by either changing your climbing direction, manually changing the rope direction or by clipping the rope in a quickdraw to guide the rope after creating a toprope.

Watch out for the rope's middle marking when belaying and tie off the end of the rope (credit: Petzl)

💡 Proper and efficient rope management is essential for passing your OVS exam. During your exam, make sure to take charge and care of the rope you are using. Practice this during ASAC weekends. Learning how to coil a rope properly when you’re done climbing is also essential.

💡 If you’re considering buying a climbing rope, look up a climbing rope buyers guide or watch a video. This article covers the basics. This video will tell you all that you’ll need to know on climbing ropes. The same author has loads of great content on climbing falls and on safety. Definitely a must-watch!

💡 Are you interested in how climbing ropes are made? Check out this video featuring climbing legend Adam Ondra.

5.2. Cord (Prusik)

Generally a cord is used as a back-up safety measure during abseiling (rappelling). The Dutch call it a ‘Prusiktouw’, ‘Prusik’ or ‘Prusik rope’, because often you’ll use a cord with a Prusik knot (which is technically not a knot, but a hitch). The diameter of the climbing rope you’re using in relation to the diameter of the cord you’re using determines the (overall) effectiveness of the Prusik knot, because a Prusik knot relies on friction between the cord and the rope. ASAC recommends a 6 mm diameter cord for general climbing purposes. A 5 mm cord might end up being better when your climbing rope is thinner (~8 mm e.g. high-end sport climbing specific rope) or when your rope is newer (less fuzzy ergo less friction ergo the Prusik won’t work as well with a larger diameter cord). In general, 6mm cord works well on 10mm ropes, whereas 5mm cord is better for 8mm ropes.

A Prusik knot on a climbing rope (credit: Black sheep adventure sports)

5.3. Quickdraws

Quickdraws ('setjes' in Dutch) are used for connecting the climbing rope(s) to the bolts ('haken') that are fixed in the rock while climbing. A quickdraw generally consists of two 'snappers' (i.e. carabiners sans locking gate) and a piece of nylon or dyneema webbing that connects the snappers, also called a 'dogbone'. The snapper which is lose and that can rotate freely is the side that goes into the bolt. The rope side has a rubber which fixes the snapper in place.

For single pitch sport climbing, quickdraws with a wide and fat dogbone are recommended (e.g. DMM Alpha Sport, Camp Photon or Petzl Spirit). This makes pulling on the quickdraw when in need a lot easier. For multi pitch climbing or traditional climbing you may want a lighter quickdraw to save on weight while climbing. It is also nice the have quickdraws with a brightly colored snapper on the rope side so it is easily identifiable as such.

Quickdraws are made and sold by many different manufacturers and come in a wide spectrum of different configurations and weights (credit: Outdoor Gear Lab).

⚠️ Make sure to clip in the correct side of the quickdraw (credit: Petzl)

5.4. Slings

Slings (usually just called 'slings', sometimes called ‘bandlussen’ in Dutch) can be used for a lot of purposes in climbing. For OVS you’ll use a sling to connect bolts to make an anchor, and on your body during abseiling (rappelling). You can also use a sling as a Personal Anchoring System (‘zelfzekering’ - for more information on the PAS see section 5.5). Slings come in different lengths ranging from 30 cm up to 240 cm (‘king sling’). For OVS purposes you’ll need at least one 120 cm sling.

Climbing slings generally are made out of nylon OR Dyneema. Nylon slings are wider, bulkier and more durable than Dyneema slings. Dyneema has a higher strength-to-weight ratio and are therefore lighter than nylon slings. However, nylon slings are more resistant to dynamic loading than dyneema slings. Here’s a good article about nylon versus Dyneema slings.

⚠️️ As a general rule you should never load your slings dynamically (i.e. fall in a sling). Especially, do not fall in your sling when you use one as part of your Personal Anchoring System (‘zelfzekering’).

Two alpine-style extendable quickdraws. The slings make the quickdraws easily extendable on the go, which can help reduce rope drag when climbing. One with a dyneema sling (left) and one with a nylon sling (pictured right). Slings can be used for quickdraws, even though they shouldn’t be loaded dynamically, because the rope will absorb most of the force during a fall. (credit: unknown)

5.5. Carabiners

There are quite a few types of carabiners. The differences between them can be generalised to 1) shape, size, and strength of the carabiner; and 2) the locking mechanism. Keep in mind there are a lot of differences between carabiners that are not described here.

The shape of the carabiner can vary depending on the use of the carabiner. The most commonly used locking carabiner shape is the HMS-type. HMS is an abbreviation for ‘Halbmastwurf sicherung’ (German), also known as ‘halve mastworp’ (Dutch) or ‘Munter hitch’ (English). HMS carabiners are designed to be used with a Munter hitch (‘halve mastworp’), which can be used for belaying (part of the outdoor multi-pitch (OVM) course). If you’re interested in different carabiner shapes and their respective uses I recommend looking that up on the internet.

While carabiner shapes are definitely interesting, we’ll stick to locking mechanisms for now. Generally speaking, there are three types of carabiners in terms of locking mechanism:

Carabiners with no additional locking mechanism. These carabiners are called ‘snappers’ and are generally only used for quickdraws. They require one action to open (opening the ‘gate’ of the carabiner).
Locking carabiners. These carabiners have a lock. In short, there are a lot of different locking mechanisms: screw gate (‘schroefkarabiner’), twist lock, twist-’n-slide lock, ball lock, magnetic lock, etcetera. ASAC prefers screw gates, but other tested and proven locking mechanisms are also fine. These carabiners generally require two actions to open (1. screw/twist/press/whatever > 2. opening the gate of the carabiner)
Carabiners that ASAC considers ‘safe-biners’. In section three we also called them ‘belay-specific carabiners’. Basically, these carabiners require three actions or more to open (1. clasp > 2. screw/twist and slide/press/whatever > 3. open) instead of two actions. Basically, they are considered by ASAC to be safer than regular climbing carabiners.

💡 ASAC instructors will want you to use a belay-specific carabiner (‘safe-biner’) for both belaying and for building a top rope belay system. The DMM Belay Master 2 (not sponsored) is a great and affordable belay-specific carabiner and is commonly used within ASAC.

Example of a recommended belay-specific locking carabiner / ‘safe biner’ (DMM Belay Master 2; credit: Outdoor Gear Lab)

⚠️ When you place your carabiner in a bolt, ASAC instructors will want you to hang it in a ‘gravity loaded’ position. This means the narrow part of the carabiner (the top side in the picture on the right) is the place where the carabiner hangs in the bolt. This way you’ll have plenty of room in the wide part to hang in gear and, if you’re using a screw gate locking mechanism, due to gravity it is less likely to unscrew itself.

⚠️ Place the carabiner in such a way that the opening is away from the rock. Together with the fact that it is gravity-loaded, this decreases the chance that the carabiner will open through movement with the rock.

⚠️️ Carabiners have a specific loading direction. A carabiner is designed to be loaded on the major axis, with the gate closed (and locked). For reference on the correct loading directions, see the figure on the right. The figure displayed under this text shows several dangerous loading directions.

Examples of dangerous locking carabiner loading (credit: Petzl)

5.6. Personal Anchoring Systems (PAS) / ‘zelfzekering’

A Personal Anchoring System (PAS) (‘zelfzekering’) allows the user to tether themselves to an ‘anchor’ (i.e. two connected bolts; a ‘verbonden standplaats’). This allows the climber to go ‘off-belay’ and to install an abseil (rappel system).

⚠️️ As a general rule you should never load your PAS (‘zelfzekering’) dynamically (i.e. fall in it). Always carefully load your PAS statically after you’ve tethered it to an anchor. Some PAS (e.g. the ones that look like climbing ropes) can be loaded dynamically, though this can still be very uncomfortable or even dangerous depending on the fall height.

💡 Ready your PAS (‘zelfzekering’) before climbing by attaching one point to your belay loop. Attach the other end of your PAS to one of the rear gear loops on your climbing harness (‘klimgordel’) with a locking carabiner, preferably a safe-biner.

The simplest type of PAS (‘zelfzekering’) is a 120 cm sling tied to the belay loop of your harness using a ‘cow hitch’ (‘leeuwerikskop’). The cow hitch has a lot of different names. Girth hitch is also widely used. The sling will then have one or two ‘overhand knots’ (‘overhandse knoop’ often called ‘zaksteek’ in ASAC) tied into it where you can attach a locking carabiner into an anchor (i.e. two connected bolts).

A simple Personal Anchoring System (‘zelfzekering’) with a regular screw-HMS-type locking carabiner and a 60 cm sling. The PAS is tethered to the harness’ belay loop with a cow hitch (credit: Vdiffclimbing.com)

Another great PAS (‘zelfzekering’) can be made using a Petzl Connect Adjust lanyard. This lanyard is specifically made to be combined with a locking carabiner or ‘safe-biner’ to make a very flexible PAS that can be loaded dynamically and is easily adjustable in length. Buy this one if you are not on a tight budget, the comfort is worth the small extra investment especially if you plan on multi-pitching in the future. There is also a version available which features an extra lanyard, which can be used during an abseil (Petzl Duo connect Adjust).

Petzl Connect Adjust Personal Anchoring System (credit: Petzl)

⚠️When you are done climbing for the day, always remove your PAS cow hitch, or other attachment method, from your belay loop and remove the knots from your sling if you use a sling as your PAS. If this hitch doesn’t regularly change position on your belay loop, it could increase the degradation of the belay loop and can be easy not to notice since you won't see it.

5.7. Helmets

Use of a climbing-specific helmet is mandatory during all ASAC weekends. Climbing-specific means the helmet is certified with an EN 12492 and/or UIAA 106 rating, which is specifically for rock climbing. A cycling helmet or other types of helmets are not acceptable since it’s rated for other purposes.

💡 The rule during ASAC climbing trips is to wear your helmet as soon as you walk off the parking lot to the climbing area. If you have a long walk ahead, make sure it’s on when the rock is in sight.

⚠️️ We strongly encourage you to also wear a helmet during your independent climbing trips. A falling rock could end your life and could then even put your friends in mortal danger (if you get knocked out during belaying for example).

Authors' notes on helmets:

You might be concerned about your looks during rock climbing. On social media you might see amazing photos and videos of professional climbers who are not wearing a helmet. There might be cool climbers standing next to you who aren’t wearing a helmet either. In contrast, you might think you look like a dork wearing your big ‘ol climbing helmet. Don’t worry, you look great <3! We would strongly recommend buying a (maybe more expensive) helmet that looks better if that’s going to make you wear your helmet longer and more often. Plus, the climbing community will likely roast you if you post a social media picture of you climbing without a helmet, they don’t take it lightly.
The same goes for if you don’t like the sensation of wearing something heavy on your head all day long, which is also understandable. A normal climbing helmet weighs around 400g. A lightweight and breathable climbing helmet (~200g) can make a big difference in feel compared to a relatively heavy helmet when worn all day. The relatively small extra investment for a lightweight, comfortable helmet is definitely worth it.

5.8. Bolts

There are a lot of different types of bolts (‘haken’). We can distinguish the different kinds of bolts in the way that they are embedded in the rock, by their material, or we can distinguish them by whether they’re A) round (‘rond’) or B) sharp (‘scherp’). For OVS purposes, the last distinction is the most important, since this determines what you can and cannot do with them.

⚠️️ For your OVS certification you’ll need to be able to recognise bolts that are not trustworthy and potentially dangerous. Corrosion can make the bolt dangerous. Generally, ‘rust’ means ‘don’t trust’. In some cases, corrosion might be only surface rust, especially in well kept and frequented climbing areas. However, in other cases, the bolt could look fine, but could be completely rusted inside the rock. Beware of humid areas (e.g. near the sea) where corrosion happens at a progressed rate.

💡 A good tip is to check the guidebook (‘topo’) for the area you’re in. Often the guidebook will mention when the route you’re climbing was bolted, who made the first ascent (when known), and most importantly for you; when the route was most recently re-bolted. In most regions, a lifespan of 10-15 years is normal for a climbing bolt. Again, beware of humid areas where the lifespan of a bolt might be much shorter.

Round bolts
Round bolts (‘ronde haken’) allow the climber to clean the route (‘ombouwen’) and/or to install an abseil system. Round bolts are most commonly found at the anchor, but there are also a lot of cases where the whole route consists of round bolts. This depends largely on the area, the bolter and the type of rock.

Pictured left: a round bolt (‘ronde haak’) made out of titanium (glue-in type (‘lijmhaak’). This bolt was placed in Cuba. Titanium bolts are preferred when climbing close to the sea because titanium is relatively resistant to corrosion. Even stainless steel bolts are known to have been completely corroded after a couple years of service near the sea (credit: Cubaclimbing.com).

Sharp bolts
Sharp bolts (‘scherpe haken’) are also commonly seen on outdoor single- and multi-pitch climbing routes.

⚠️️ You cannot lower or rappel on sharp bolts! As the name suggests, these sharp bolts will cut your rope when it slides through the bolt.

When the route is bolted using sharp bolts, only the anchor (‘anker’, ‘standplaats’ or ‘relais’) at the end of the pitch will have round bolts or sharp bolts with round rings installed, so you can clean the route and/or install an rappel (abseil) system from those round bolts.

Pictured left: A sharp expansion-type bolt (very common)
(credit: Vdiffclimbing.com)

Pitons
Sometimes you will encounter old pitons ('mephaken') in the seams and cracks of a climbing route. These historic bolts usually pre-date the normal bolts in the route. Nowadays, they are not used anymore for bolting sport climbing routes. This type of sharp bolt is generally very old and rusty because of it's age. You can choose to use these bolts, but be aware that they might break out when you fall on them.

A piton embedded in a crack (credit: Adirondack Explorer)

5.9. Anchors

An anchor (‘anker’, ‘standplaats’ or ‘relais’) is a pair of two (often, but not always, connected) bolts. An anchor marks the end of a climbing pitch and allows the user to install a top roping system (‘top rope bouwen’), to clean the route (‘ombouwen’), to abseil (rappel) and more.

An anchor can be found at the end of most single-pitch sport climbs. Anchors can also be found at the end of most pitches on a multi-pitch route or sometimes at the end of a single-pitch traditional (trad) climbing route. Often anchors are equipped with maillons (quick links) or round rings. These pieces of equipment will be attached to the bolts. This way the bolts won’t wear out before they’ve reached their lifespan and allows for lowering with sharp bolts.

⚠️️ The golden rule for climbing is redundancy. Therefore, the anchor needs to be redundant. This means that if the first bolt fails, a second bolt / anchor point will function as a back-up. This can be achieved by connecting two or more bolts.

⚠️ In rare cases you will find a single bolt anchor on single-pitch climbs (not uncommon in Germany). Be very careful with those. Check the guidebook (‘topo’) for when the route was last re-bolted for the age of the bolts. Never set up a top roping system without a back-up bolt.

⚠️ Some climbing anchors might be connected with a cord or a sling. Do not blindly trust this for a top rope or an abseil! Always inspect it thoroughly before using it, especially for sun (UV) damage. When in doubt, connect the bolts yourself (section 7.1).

💡 For OVS you’ll need to know how to connect the two anchor bolts (if they’re not already connected by chains) in order to make the anchor safe (redundant) for installing a top roping system (‘toprope bouwen’) and sometimes for cleaning the route (‘ombouwen’). Both these techniques will be discussed in section 7.

💡 Sometimes at the crag (‘klimgebied’) there will be an anchor at ground level. This allows for easy and safe practice and instruction.

Sealed anchors (‘verbonden standplaatsen’) and open anchors (‘onverbonden standplaatsen’)
Often, the person who has bolted the route will have pre-connected the two anchor bolts with chains. This is called a ‘sealed anchor’ (‘verbonden standplaats’). This type of anchor system requires almost no work for installing a top roping system (‘toprope bouwen’). A ring (pictured on the bottom of the anchor in the second photo) or maillon (pictured on the third photo, attached to the sharp bolts) will then be installed on the lowest part of the anchor from where you can hang most of your equipment. Anchors are sometimes left ‘open’ due to the cost of materials.

In the EU you will find mostly offset anchors (sealed anchor in the middle, open anchor on the right). In that case, the bottom bolt of the anchor will carry most of the forces while the upper bolt functions as a back-up. In the picture on the left the lower bolt on the sealed anchor is equipped with a pig tail (‘Ossenkop’) which makes cleaning very easy (‘ombouwen’ won’t be necessary in that case). However, they have other disadvantages. Please inform yourself on the advantages and disadvantages of pigtails.

(credit: Hownot2.com; Alpinesavvy.com).

6. OVS knots and hitches

For OVS you will need to know the following knots and hitches:

Figure eight (‘achtknoop’)
Figure eight on a bight (‘dubbele achtknoop’)
Overhand knot (‘overhandse knoop’, ‘zaksteek’)
Cow hitch (‘leeuwerikskop’, also often wrongly called ‘ankersteek’ in ASAC)
Classic Prusik knot (‘Prusikknoop’) - section 6.1.
Optional but useful: Clove hitch ('hele mastworp') - section 6.2.
Optional but useful: Munter hitch ('halve mastworp') - section 6.2.
Optional but useful: Double fisherman’s knot (‘dubbele vissersknoop’)’

This guide assumes you already know the first four knots, their uses and their weaknesses. If you don’t, educate yourself with the links provided above. The next part of this guide will focus on the classic Prusik knot (‘Prusikknoop’).

6.1. The Prusik knot / friction hitch

The classic Prusik knot (‘Prusikknoop’) (pictured right) is an important tool in every climbers’ arsenal. A correct Prusik knot will slide over the rope it is attached to when assisted gently by hand. The Prusik will block (i.e. stop sliding over the rope) when heavily loaded. This means the Prusik can be used as a back-up when abseiling (rappelling). In a situation where an abseiling climber becomes unconscious and lets go of the belay device, the Prusik will stop the unconscious climber from descending any further.

💡 There are also other types of friction hitches that can be used instead of a Prusik. You can read up on them here. Prusik knots can also be used to ascend on a rope (for self rescue). You can read up on that here. This information is useful, but not needed for your OVS exam.

As mentioned earlier in section 5.2, the Prusik knot relies on friction between the cord with the Prusik knot and the climbing rope. The diameter of your cord should be 60% to 80% of the rope’s diameter. If you use a cord that is too thin, it will tighten easily around the rope and will be difficult to move freely. If you use a cord that is too thick, it won’t have enough friction to lock up when you need it to. With the correct diameter cord for the rope you’re using, a Prusik only needs two folds to function. If the Prusik is still sliding when loaded, a third fold can be added. If the prusik isn’t sliding at all, remove a fold.

How to 'fold' a Prusik knot (credit: unknown)

7. OVS techniques

Now that we’ve covered materials, knots and hitches, we can begin discussing the biggest part of OVS, the climbing skills and techniques. During your OVS exam, you will be tested in your proficiency in the following skills and techniques:

Connecting two anchor bolts (‘haken verbinden’);
Making a top rope system (‘toprope bouwen’);
Cleaning the route (‘ombouwen’) in three different ways;
1. Standard cleaning practice (‘ombouwen’);
2. Cleaning with little room in the bolts (‘ombouwen met weinig ruimte in de haken’);
3. Cleaning a route from a single bolt (retreating from a route on a single bolt) (‘ombouwen op één haak’);
Abseiling (rappelling);
Other OVS skills like warming up, reading the guidebook and risk awareness; these are explained in the other sections of this guide.

The skills and techniques mentioned above are explained and summarised in the following paragraphs.

7.1. Making a top rope system and connecting two anchor bolts

When making a top rope system (‘top rope bouwen’), it is very important to do it right. A wrongly installed top rope system can be deadly (not only for you, but also for someone else who’s going to climb on your top rope). A top rope system can only be made on a redundant anchor (i.e. two connected bolts). It is good practice to always make a top rope system on your own gear (i.e. the rope goes through your safebiner, that is in turn attached to the anchor), and specifically not to top rope through the anchor bolts directly. This is important to prevent unnecessary wear and tear of the anchor. To make a top rope system on your own gear, the following steps can be followed:

You are lead climbing and arrive at the anchor (‘anker’, ‘standplaats’, ‘relais’). You place a quickdraw (‘setje’) in the closest bolt and ask your belayer for a block using the standard command (‘[name], block!’). You now hang comfortably suspended at the anchor. Next, place your PAS (‘zelfzekering’) into one of the bolts and lock the carabiner of the PAS and load your PAS statically.
The anchor might be ‘sealed’ already (see section 5.9), in that case, resume with the next substeps ⚠️If the anchor is ‘sealed’ by cord or sling be very suspicious; it is recommended to connect the bolts yourself in this scenario (step 3 and onwards).

2.1. Place a safe-biner gravity-loaded in the lowest bolt or ring available.

2.2. Ask your belayer for some slack (by yelling: '[name] touw uit!'). You can then take your climbing rope from the quickdraw and place it in the lower part of the safe-biner. You can then also take the quickdraw from the anchor.

2.3. Lock the safe-biner, and ask your belayer for a block (‘[name], block!’). You can then check the system by checking if the anchor is sealed correctly, checking if the rope goes through the safe-biner, and checking if the safe-biner is closed. Next, check If you are indeed safely hanging in the rope and whether your PAS is now unloaded (no longer being used since you should be hanging in the rope because your belayer has blocked). Then take out your PAS and ask your belayer to lower you to the ground. During your descent, you can take your quickdraws from the bolts.

If the anchor is ‘open’ (i.e. the bolts are not connected yet; see section 5.9), there are several ways you can safely connect two anchor bolts. For now we’ll stick to one method which is relatively easy to learn: by using a sling and two locking carabiners (‘karabiners’):

Place one locking carabiner in either bolt, one of these locking carabiners should be a safe-biner. The safe-biner should be placed in either the lowest bolt or the bolt that is most conveniently accessible. The carabiner in the other bolt can be a normal locking carabiner. Later, you will use the safe-biner to run the rope through for the top rope.

Make sure the narrow part of the carabiner is hanging on the bolt side (gravity loaded). Also make sure the carabiner gates are facing in the opposite direction.

When determining the direction of the carabiners (gate left or right), be mindful of any rock crops which might be able to screw open a locking carabiner. Preferably the rock is not able to touch the screw on the gate of the locking carabiner.

Connect the two carabiners with a sling, clipping the sling in both carabiners. In the safe-biner, clip the sling through the upper part of the carabiner (above the plastic gate clip a.k.a. ‘het klepje’).
Tie off the sling using an overhand knot (‘overhandse knoop’). Make sure the sling is not under visible tension, but also not overly slack.

⚠️️ It can be dangerous when there is too much slack in the sling or when the sling is not tied off. In that case, when the load-bearing bolt rips or breaks the system will ‘fall’ dynamically in the sling which might cause it to fail.

Ask your belayer for some slack (by yelling: '[name] touw uit!'). You can then take your climbing rope from the quickdraw (‘setje’) and place it in the lower part of the safe-biner. You can then also take the quickdraw from the anchor.
⚠️Lock both carabiners.
Ask the belayer to take you tight (take slack out of the system) (‘[name] block!’). You will now hang in the rope and the PAS should be unloaded.
⚠️Check the system. Make sure the anchor is redundant, and check if the carabiners are locked, gravity loaded, and that the gates face away from each other (‘opposite and opposing’). Does the rope run through the bottom part of the safe-biner?
Once you are sure the system is functional and safe, you can take your PAS from the anchor and ask your belayer to lower you to the ground (‘[name] lower!’). During your descent, you can take your quickdraws from the bolts (if doing so, use a series of block and lower commands OR use hand signals pre-discussed before climbing).

A finished toprope anchor in ASAC style on an 'open' anchor (note: there's still a PAS in the anchor behind the black safebiner). Credit: Itxaso

7.2. Cleaning the route

This section will describe three ways of ‘cleaning’ the route (‘ombouwen’). Two of these techniques can be used to clean the route from the anchor. The third technique is used to retreat from a single bolt somewhere along the route.

7.2.1. Standard cleaning practice (eight-on-a-bight-method)

You’re finished with the route and want to clean the route without leaving any of your gear.

Establishing yourself on the anchor
- You arrive at the anchor (‘anker’, ‘standplaats’, ‘relais’). Place a quickdraw in the closest anchor bolt. In case you were climbing on top rope there is no need to place a quickdraw at the anchor. Then, ask your belayer for a block using the standard command (‘[name], block!’) You now hang comfortably suspended at the anchor.
- Attach yourself to the anchor using your PAS (‘zelfzekering’). ⚠️ Make sure the carabiner on your PAS is locked. Rest your weight on the PAS by asking your belayer for slack (‘[name] touw uit!’).
Pull up a little slack and push a bight of the rope (see image below) through the main anchor point (if the anchor is sealed, i.e. pre-connected by chains), or else through both round bolts (‘ronde haken’) of the anchor.
Lock-in and check in:
- Tie a figure eight knot on the bight and clip this to your belay loop using a locking carabiner (preferably a ‘safebiner’, if you use a regular carabiner you can use a quickdraw as a back-up).
- ⚠️Check the system: is your new figure eight-knot on a bight tied correctly? Is it attached to your belay loop and is the locking carabiner closed properly? Does the rope run through the main anchor point (in case of a sealed anchor) or through both bolts (in case of an ‘open’ anchor)?
Untying the original knot:
- Untie from the end of the rope (the eight-knot you originally tied in with when you were still on the ground).
- Pull the end of the rope you just untied through the anchor.
Removing the gear
- Remove the quickdraw which isn’t holding your weight (if it’s there). Ask your belayer to take you tight (‘[name], block!’).
- Rest your weight on the rope, you should now hang in the rope and the PAS should be unloaded. Check again if the system is safe. If the system is safe, remove your PAS (‘zelfzekering’). You can now ask your belayer to lower you to the ground and take out any remaining quickdraws (‘setjes’) on the route as you go down.

Cleaning the anchor in the standard way on a sealed anchor. A quickdraw can be used as a back-up when you don't have a safebiner to use (credit: Petzl)

Video on how to clean a route using the eight-on-a-bight-method (credit: IBEX)

7.2.2. Cleaning with little room in the bolts

Sometimes, you won’t be able to push a bight of rope through the anchor. This depends on the thickness of your rope and the type of anchor and/or bolts. In this case, you must use a slightly different method: cleaning with little room in the bolts (‘ombouwen met weinig ruimte in de haken’). As with the ‘standard method’, you will remain ‘on belay’ during the whole setup.

Establishing yourself on the anchor:
- You arrive at the anchor (‘anker’, ‘standplaats’, ‘relais’). Place a quickdraw in the closest anchor bolt. In case you were climbing on top rope there is no need to place a quickdraw at the anchor. Then, ask your belayer for a block using the standard command (‘[name], block!’) You now hang comfortably suspended at the anchor.
- You now hang comfortably suspended at the anchor.
- Attach yourself to the anchor using your PAS (‘zelfzekering’). ⚠️ Make sure the carabiner on your PAS is locked. Rest your weight on the PAS by asking your belayer for slack (‘[name] touw uit!’).
- Recommended optional step (not pictured): connect the bolts in case of an 'open' anchor (i.e. the bolts aren't connected) with a sling or a cordelette. This will reduce the risk of making a long fall in case the bolt with your PAS breaks out during the next step.
Pull up around three meters of slack rope and tie a figure eight on a bight. Make sure you have enough rope to pull a single strand of rope through the anchor later and to make a new eight knot in your belay loop using the same strand. Clip the eight to your belay loop with a locking carabiner.
- ⚠️This step is essential, because the rope must be attached to you at all times, to prevent it from falling down (leaving you stuck on the rock without a rope).
- ⚠️Check the figure eight on a bight and make sure the carabiner is locked.
Untying and feeding the end of the rope through the anchor:
- Untie from the end of the rope (the eight-knot you originally tied in with when you were still on the ground). Step 3 in the image below.
- Feed the end of the rope through the main anchor point (sealed anchor) or through both anchor points (open anchor). Step 3 in the image below.
Tie in to the end of the rope with a figure eight (like you would tie in on the ground) and check the knot.
- ⚠️Check the system. Does your new tie-in connect to your belayer? Does it go through the main anchor point(s)? Is the figure eight tied correctly?
Remove the locking carabiner on your figure eight on a bight and then untie the figure eight on a bight.
Removing the gear:
- Remove the quickdraw which isn’t holding your weight (if it’s there). Ask your belayer to take you tight (take slack out of the system) (‘[name], block!’).
- Rest your weight on the rope, check everything again and then remove your PAS (‘zelfzekering’). You can now ask your belayer to lower you to the ground and take out any remaining quickdraws (‘setjes’) on the route as you go down.

Cleaning with little room in the bolts (credit: Petzl)

Video on how to clean a route with little room in the bolts (credit: IBEX)

7.2.3. Cleaning on a single bolt (retreating)

This technique (‘ombouwen op één haak’) can be used when you want to retreat from a route that is too hard to be climbed all the way to the anchor. Using this technique you will be able to clean the route in a relatively safe way, even though you’re not lowering from the anchor.

The route is too hard. You won’t be able to make it to the anchor and nobody else wants to climb it. It’s time to retreat.
Ask your belayer to take you at the last/highest quickdraw (‘[name], block!’).
Attach your PAS (‘zelfzekering’) to the bolt. Place it under the quickdraw (‘setje’), so the quickdraw is easily removed after this step. ⚠️ Make sure the carabiner on your PAS is locked.
Remove the quickdraw from the bolt.
Check the bolt. Is it a round bolt (‘ronde haak’) or a sharp bolt (‘scherpe haak’)?

Round bolt: nice! You can use the bolt to lower.

Sharp bolt: hang another piece of gear in the bolt. You will have to leave this piece of gear 🙁.

Attach a Prusik cord (‘Prusik touw’) to the strand of the rope that goes from the bolt to the belayer using a Prusik knot (‘Prusik knoop’) (see section 5 to see how to fold the Prusik knot).
Attach the Prusik cord to the belay loop of your harness using a locking carabiner, preferably a safe-biner.
Clean the bolt as you would clean the anchor with little room in the bolts (as described in section 7.3.2.)
⚠️ Check the system: check if the Prusik knot is functional (does it ‘bite’ if you aggressively slide it up or down over the rope?); are the locking carabiners closed?
Ask your belayer to take the slack out of the system (‘[name], block!’), and remove your PAS from the bolt.
Hold the Prusik knot so you are able to carefully slide it over the rope when lowering.
You can now lower from the single bolt to the ground, taking out any remaining quickdraws (‘setjes’) from the route as you lower. In case the top bolt fails, the Prusik knot will make sure you’ll fall in the next bolt that is still clipped into the rope. This adds some redundancy to the system.
Take care that the Prusik doesn’t slide into the belayers’ belay device.

Cleaning and lowering from a single bolt. Notice the use of a snapper in the upper bolt and a Prusik knot to make the system more redundant. If the upper bolt fails, the climber will fall into the next quickdraw (credit: NKBV)

Video showing how to retreat from a route on a single bolt (credit: IBEX)

Please note:
The described technique only works on round bolts (‘ronde haken’). If you’re on a route with sharps bolts (‘scherpe haken’), ask someone else to climb and clean the route for you, or alternatively add a piece of material (e.g. a snapper or a locking carabiner to ‘create’ a round bolt). You will then have to leave this piece of equipment on the route.

💡 If you have to leave a piece, it is preferred to leave a snapper on the route, and not a maillon (also known as a quick link. Usually you can take a snapper from one of your quickdraws (‘setjes’). If you don’t feel comfortable with lowering off a single snapper, leave a locking carabiner. Some people will use a maillon instead. This is not recommended. Why? (Credit: AlpineSavvy, link)

Maillons can make it harder for the next person up to clip a quickdraw into the bolt;
If the next climber clips a quickdraw over the top of your maillon and keeps climbing, a fall at that point might leverage the snapper on the draw and break it;
Especially if it stays there for a while, maillons can start to rust close and can be very hard to remove.

⚠️If you encounter a maillon in a bolt when climbing, always clip your quickdraw in or under the maillon. If you clip the quickdraw over/above a maillon, your quickdraw might break during a fall.

💡 If you’re going to try a route that might be too hard for you and there is no one else around who wants to climb and clean the route in case you don’t make it, make sure to check beforehand if the route has round bolts (‘ronde haken’) or sharp bolts (‘scherpe haken’). If the route has round bolts, prepare to be able to clean on a single bolt. If the route has sharp bolts, be ready to bring an extra piece of gear to leave in the route, in case you have to retreat. Alternatively, consider climbing another route.

7.3. Abseiling (rappelling)

Abseiling is a technique that is sometimes used to access areas which are not accessible from the ground (you’ll need to abseil in from the top of the crag) or in some areas where you may not be allowed to lower directly from the bolts to prevent them from wearing out. Abseiling is also extensively used to descend from multi-pitch climbs (OVM course). The abseil is used to lower safely from an anchor to the ground without having someone else belaying you. To abseil, you’ll first need to ready the rope, then you can build the abseil, after which you can lower safely.

7.3.1. Readying the rope for the abseil

Connect yourself to the anchor (‘standplaats’) using your PAS (‘zelfzekering’). ⚠️Make sure the carabiner on your PAS is locked. If the anchor is ‘open’ (i.e. not connected safely), connect the bolts first (section 7.1).
If you climbed up first, and now want to abseil, you will have to go off-belay first. You need to go off-belay because you’ll need all the rope for yourself. When off-belay, you will only be attached to the redundant anchor. To go off-belay, you use the command ‘[name] stand!]. The belayer will now remove their belay device from the system and confirm this with the climber (‘[name], off belay!).

⚠️Never use the ‘stand’ command in any other situation, this can be a deadly mistake!

Pull up three metres of slack, tie an overhand knot to your harness belay loop (or connect it to a spare carabiner if you have one, or tie a figure eight on a bight and use a locking carabiner, depending on how protective you want to be with possibly dropping the rope). Once rope is secured to you, untie your figure eight from the belay loop and pass it through the main anchor point.

Alternatively, you can pull up the rope from the belayers’ side, pass the end through the main anchor point (tie a fat knot in the end, see step 4), and then pass the rope through until you find the middle marking (step 5). This way you stay tied in longer.

⚠️️ Do not pull the rope through a sharp bolt hanger. Always put it through a round point such as a round bolt, a ring or a maillon. Ropes do not like the sharp bend radius of a sharp bolt.

⚠️Tie a fat knot (an eight on a bight, a regular eight or an overhand) in the rope end you’ve just pulled through, about 1 metre from the end of the rope. This stops you from accidentally abseiling off the end of the rope. Later, you’ll tie another knot on the other end of the rope. At this point you may release the rope from your harness.
Pull the rope through the main anchor point until you’re at the middle of the rope. Most ropes have a middle marking (a black stripe). If you don’t have a middle marking, have your belayer notify you if you before you pull their end of the rope off the ground.
As you’re pulling the rope through the anchor point, begin coiling it around your arm or at your feet.
⚠️Tie a knot (step 3) on the other end of the rope. If you are rappelling from the top of a pitch you just climbed, have the belayer confirm the knot on their end of the rope.
Shout ‘watch out, rope!’ in whatever language that is applicable to the area you are in (Dutch: ‘kijk uit, touw!’; French: ‘attention, corde!’; German: ‘Achtung, Seil!’; Spanish: ‘Atención, cuerda!’).

When you are certain that no one could get hit by your ropes, you can throw them. Take the first bunch of rope one hand and the second bunch with the other hand. Throw both bunches down independently. When you throw the first bunch, remain attentive to the rope near the anchor as it may move the middle of the rope away from the main anchor point(s).

If there are climbers beneath you, you should either wait and let them complete their climb, or seek their permission to gradually lower your rope ends down. Although gradually lowering your rope may cause your ropes to get stuck on rock features or bushes, it will be far less dangerous for any person who is leading their way up.

Always tie off the rope strand ends before abseiling (credit: Petzl)

7.3.2. Building the abseil

To build the abseil you will either need:

a separate 60 cm sling that is tied to your belay loop using a cow hitch;
an overhand knot in the 120 cm sling that you may be using as a PAS.
A daisy chain PAS.

Always make sure you have the necessary equipment to abseil when you are still on the ground. If the rope is prepared correctly, you may build the abseil using the following steps.

Attach your Prusik cord (‘Prusiktouw’) to both strands of the rope using a Prusik knot (Section 6). If your Prusik cord is still ‘open’(i.e. not connected on the ends), close the cord using an overhand knot or a double fisherman’s knot (it is strongly recommended to have a closed cord prepared).
Check if the Prusik ‘bites’: does it slide if you suddenly pull on it? If it doesn’t, loop the Prusik once more. Does it bite too easily? Use one loop less. If you have your hand on the Prusik, it should slide over the rope, and bite when it is suddenly loaded heavily. The Prusik functions as a stop to your fall in case you might be rendered unconscious, or it can be used as a brake during the abseil.
Attach the closed Prusik to your belay loop using a locking carabiner (preferably a safebiner). ⚠️ Lock the carabiner.
Grab both strands of the rope above the Prusik and pull up some extra slack through the knot. Then fold the strands into two bights and push them through your ATC belay device (‘teeth’ of the ATC up for lower friction when descending, teeth down for higher friction when descending).
Attach a locking carabiner through both rope strands and through the wire loop on your ATC, then attach this carabiner (with ATC) to your 60 cm sling or to the knot in your 120 sling that you may be using as a PAS. ⚠️ Lock the carabiner.
⚠️Check the system on these five points (from top to bottom):
1. Does the rope run through the main anchor point(s)?
2. Is the carabiner on your ATC locked and does it run through both strands of the rope and the main loop of your ATC belay device?
3. Is the carabiner on your Prusik locked and is the Prusik knot functional?
4. Can the Prusik reach the belay device? If the answer is yes, then either your ATC is not far away enough, or your Prusik is too long.
5. Did you tie knots at the end of both strands of the rope?

Abseil system example using a 60 cm sling attached to the secondary belay loops using a cow hitch (it can also be safely attached in a similar fashion to the main belay loop instead) and the Prusik cord is attached using a standard friction hitch; preferably use a Prusik knot instead of the pictured hitch, but this is also functional and safe (credit: Vdiffclimbing.com)

7.3.3. Descending on the abseil

Make sure you did the five-point check (previous section)
Make sure that the ATC is pulled up on the rope strands enough, so that when you remove your PAS (‘zelfzekering’), you won’t ‘fall’ into the ATC. This way you can also test the abseil system before removing your PAS.
Unclip your PAS from the anchor.
Keep one hand on the rope strands above the Prusik and one hand over the Prusik. Lean your weight back, sit back in your harness and keep your body in an L shape with your feet wide apart. You can opt to wear a glove on your bottom/Prusik hand to reduce discomfort and a dirty hand.
Carefully slide the Prusik over the rope strands. This will make you go down. Walk backwards down the rock, while making sure to look down/behind to see where you’re going. Descend the ropes in a controlled and uninterrupted manner, avoiding any bouncing, jumping, or swinging movements that can create excessive strain on the anchor and potentially cause your ropes to get damaged if they rub against rough surfaces.
When descending past a roof, position your feet on the edge and gradually lower your body down. Once your body is past the roof, release your feet to prevent any impact with your head. Be mindful of the sharpness of the edge on the roof and choose a place that will be kind to your rope.
As you lower yourself down, maintain a constant flow of rope through the system. With practice, you will determine the appropriate speed for feeding the rope while maintaining control.
Once you (and your friends) have descended, proceed to retrieve the rope. Begin by untying the knots from the ends of the rope, and pull the rope from the anchor. Before the rope is about to fall from the anchor, issue a warning shout such as 'watch out, rope!' (preferably use the language applicable to the area) to alert your partners and/or others nearby. ⚠️Be cautious as the falling rope may cause any loose rocks to fall.

Holding the Prusik and rope while descending (credit: Vdiffclimbing.com)

Rappelling technique demonstration by Tello
(CC BY-NC 4.0)

Video on how to make an abseil/rappel (credit: IBEX)

8. Other OVS skills

This section goes into some other OVS-related skills that will help you to become a full-fledged independent outdoor climber.

8.1. Warming up

Always warm up before climbing, even if others might choose not to. Warming up prevents injury and primes us for performance and even the mental aspects of climbing. It is always a good idea to combine a general warm-up (using big muscle groups in order to ‘recruit’ the muscles and elevate the heart-rate) with a more climbing specific warm-up (pulling on holds on the ground to wake up the fingers). About 5 to 15 minutes is good to get everything done. Creating a routine that works for you is a great idea and will help you focus on the task at hand.

When you’re done warming up on the ground you can warm up fully by either/and/or:

Climbing a route that you know and/or a route that is well within your capability;
Climbing a route with bigger holds;
Climbing a more challenging route in sections (e.g. from bolt to bolt or five moves at a time), avoiding excessive build up of ‘pump’ in the forearms.

8.2. Reading the guidebook

A guidebook, or a ‘topo’ is a book in physical or digital format in which the climbing area is described and the routes are documented. Sometimes the area is so large or popular that there are more than one guidebook available.

A climbing area, e.g. Berdorf or Ceüse, consists of multiple sectors or (usually called ‘gebiedjes’ in Dutch). Each sector will consist of a bit of rock with multiple routes. The routes are usually indicated with a line on a drawing or a photograph. On each sector, the guidebook will probably contain the following information:

The geographical orientation of the sector (e.g. south face, north face etc.)
The names of the routes;
The grade;
Who bolted it and when;
Who did the first ‘free’ ascent (i.e. on lead, without the use of aid, not to be confused with 'free solo') and when they did it;
The length of the route;
The protection (e.g. the amount of bolts);
Indicators of the quality or style of the route.

To determine the sector(s) where you want to climb, it can be nice to skim the guidebook for sectors with a good amount and variety of routes, and to assess the (consistency in) difficulty of the routes. It is also often a good idea to look at the geographical orientation to assess the climbing conditions (e.g. usually on a hot summer day a north face will be nicer to climb on and vice versa).

Climbing grades
Usually in Europe, bolted ‘sport’ routes will be graded using the French numerical grading scale. The French grade is used to give potential climbers an idea of the general experience they’ll have on the route in terms of overall technical difficulty and strenuousness. There are other grading systems that work in other ways, e.g. grading scales that only give an indication of the hardest move on a route, the protection and potential danger of the route, but we won’t talk about those systems in this guide.

The French climbing grade consists of a number (from 1 to n, where 1 is the easiest and n is the hardest; currently in the 9’s), followed by a letter (a, b, or c in lowercase), indicating a subdivision of difficulty within the number grade. The use of uppercase letters (e.g. A, B, C) indicates that it is a boulder (French boulder grade), and not a sport route. Sometimes the letter is followed by a ‘+’, indicating a substep of difficulty between the letter grades.

3a > [...] > 6a+ > 6b > 6b+ > 6c > 6c+ > 7a > 7a+ > 7b > [...] > 9c

The grade will give no indication of the subjective quality of the route. It is important to note that all grading scales are inherently a subjective measure. Although there have been attempts to make it more objective. Because grades are so subjective, it is probably wise not to let the grade of the route determine your climbing experience too much.

How are grades established?
The first free ascensionist (i.e. who first climbed it on lead without the use of aid) will give their subjective opinion on the grade based on their experience on the route and in regard to other previously established routes that they have climbed before, where other routes in the area are the prime candidates for comparison. Other ascensionists who follow will then give their opinion on the grade. This way, over time a public consensus establishes the grade. Generally, it is considered that a definitive and valid opinion on the grade can only be given after having free climbed the route (i.e. on lead with no falls, not to be confused with free solo).

In many climbing areas the lower grades are more ‘compressed’ than the higher grades. This means that steps between the lower grades can be bigger. Also the lower grades often are a bit ‘sandbagged’, which means that the difficulty through the viewpoint of consensus is probably higher than the grade in the guidebook would suggest. Often this has to do with the historical progression of climbing grades (7a used to be the hardest 'free' grade for a very long time) and with the routes changing over time (the holds on the route can wear out over time). Sometimes guidebook authors will change the grade of the route to a more modern standard, but also often the historical grade will prevail over modern consensus.

Ethics regarding ‘claiming’ a grade
Generally people will only ‘claim’ a grade if they have free climbed the route (i.e. on lead with no falls). This is a pretty arbitrary rule that has been established organically within the climbing community over the years. Therefore, don’t sweat it too much. Of course, it is also possible to claim the grade without having free climbed it (e.g. on top rope, or on lead with falls). Generally it is considered good practice to mention the style in which you have climbed the route when claiming the grade in front of others. Of course, it doesn’t really matter that much, as long as it sits right with you.

8.3. Risk awareness and risk assessment

Before climbing, always assess the potential risks involved. It can be useful to think through risk systematically. First, consider the likelihoods and potential consequences of these risks, then consider the control measures you might take to mitigate these risks, and lastly consider the remaining risk. Are you willing to accept the remaining risk?

Before you set off from the ground, it can be helpful help to ask questions, such as:

Do I know where the route goes?
Is there likely to be any loose rock?

⚠️It’s typical to yell ‘rock!’ (‘steen!’ in Dutch) when a rock or any other item (e.g. a belay device) falls. It’s also typical for people to look up when they hear this, but it’s actually safer to seek shelter and to look straight ahead.

How is the bolting?
- What’s the quality and age of the bolts?
- How’s the height of the first bolt?
- How far is the distance between the bolts?
How complex is the climbing?
Do we have all the necessary equipment?
What’s the weather prediction like (will it rain)?
How are you feeling?
How is your climbing partner feeling?

This table might help you to think about risks during climbing and planning ahead to mitigate and/or face the risk. It is purely an example of course.

9. Tips for your OVS exam

What is checked during the exam?
Below this text you can find the sheet that is used by the instructor to judge whether you are able to single-pitch climb outside independently and safely. During the exam, you will have to demonstrate the techniques as described in section 7 (making a top rope, cleaning the route, cleaning with little room in the bolts, cleaning on a single bolt / retreating, and building an abseil). You will also have to demonstrate that you’re able to lead climb on real rock. The instructor will also weigh in your knowledge and practice of:

The partner check;
Knots;
Clipping in quickdraws;
Belaying skills;
Rope management;
Foot faults;
Risk assessment;
Insight;
Ethics.

How to deal with things learned outside of ASAC
You might have experience climbing outside in another country, with your friends outside of ASAC, or with another climbing group. You might have learned certain techniques during that time that you already use or have used. The techniques you have already learned might be safe, but they might not be ‘ASAC-proof’. This means you won’t be able to gain your OVS status using them. It’s that way for uniformity and therefore safety. If you have learned certain techniques previously that differ from this guide, I would recommend not sticking to them, and to learn the ‘ASAC-approved’ way instead.

Practising OVS techniques at home
You can easily practice OVS techniques at home by using a chair or your kitchen cabinets as an anchor. Alternatively you can buy two ‘aanlegringen’ at the local hardware store or online and screw them onto a piece of wood to make a homebrew anchor to practice on.

Immersing yourself in climbing culture
Go out there and meet other climbers! Also, there is a lot of climbing content available online for free these days if you want to immerse yourself from the comfort of home. Through this you can familiarise yourself with climbing techniques, ethics and culture well before you ever step foot outside.

10. Questions for practice

No answers, only questions. For some questions there is not right or wrong, they’re only intended to make you think.

Ethics

In what ways can climbers minimise their impact on the local environment?
What’s the best way to go to the toilet in a protected climbing area?
You are going to the climbing area Sy in Belgium. How would you prepare for this trip?
Why is spending some money in the area beneficial to the acceptance of climbing in the area?
Somebody forgot to remove their chalk marks. What do you do?
Someone you don't know is playing loud music at the crag. What do you do?
There’s a tree on the route and you might fall. Do you pull on the tree?
It's been raining a bit and your climbing shoes got dirty in the mud. Is it okay to start climbing?
Is it okay to climb wet rock?

Dutch

What’s a ‘zelfzekering’?
What’s a ‘setje’?
What does ‘ombouwen’ mean?
In an area with only Dutch climbers, what would you shout before pulling down a rope?

Bonus: what would you shout in French, German and Spanish areas?

How would you ask your Dutch belayer for slack?

Materials

Why is climbing rope ‘dynamic’?
Why does the diameter of the Prusik cord matter?
What kinds of slings are there and what are their pros and cons?
What’s a bad way to load a carabiner?
What kinds of carabiners are there and what are the differences?
What’s a PAS and what are the pros and cons of a PAS made out of a sling?
Why can’t you use a cycling helmet for climbing?
How do you judge whether a bolt is safe to use?
What kinds of bolts are there? Name the two most important categories and their differences.
What’s the difference between an open and a closed anchor?

Knots and hitches

What knots and hitches are used for OVS?
What are their Dutch (commonly used) names?

OVS techniques

When is it necessary to connect two bolts?
What equipment do you need to bring to connect two bolts and to build a toprope on it?
You find a closed anchor which is closed with a cord (the two bolts are connected by a cord). Is it necessary to connect the bolts?
Is it safe to hang in a toprope on a close anchor sealed with a chain?
What two techniques are there for cleaning the anchor and why would you choose one over the other?
You have a PAS on a 120 cm sling. Your arms are not that long. What would you prepare to make the PAS practical for cleaning the anchor?
What are the common rope commands used during cleaning?
You want to abseil but the anchor consists of two sharp bolts and nothing else. What do you do?
What equipment do you need to abseil?
In what situations would you want to abseil?
Why would you use a Prusik knot during an abseil?
How would you check the functionality of your Prusik knot?
What are the five points you check before removing your PAS in an abseil?

OVS skills

Someone told you about a cool route in the area and you’re psyched to try it. How would you find the route and how would you prepare before?
You arrive at the foot of the route. You’re already warmed up. What do you do before you start climbing?
The route you want to do is a little bit harder than you’re used to and consists of sharp bolts. What’s your thinking process, what do you do and why?
The first bolt is 5 metres up the route. What do you do and why?
It is going to rain in the afternoon and the crag you want to visit is only accessible by abseil. Would you go climbing there? Why / why not?

11. Other resources and materials

Other interesting resources with useful information regarding climbing safety and technique:

AlpineSavvy - https://www.alpinesavvy.com/
Petzl tech tips - https://www.petzl.com/INT/en/Sport/Rock-climbing
Vdiffclimbing (American systems focused) - https://www.vdiffclimbing.com/
NKBV kenniscentrum (Dutch) - https://nkbv.nl/kenniscentrum/?sort=undefined
NKBV - climbing areas around the Netherlands (Dutch) - https://nkbv.nl/kenniscentrum/klimmen-rond-nederland.html
NKBV - info sport climbing outside and maps of climbing areas around the Netherlands (Dutch) - https://nkbv.nl/sport/sportklimmen/buiten/
Comfort-zone - a website focusing on Belgian climbing areas - https://comfort-zone.be/

13. Feedback

Would you like to leave feedback on this guide? Please leave your feedback in this form and we’ll look into it!

14. Changes to this guide or milestones

Version 0.1 the first draft written in 2022. Other people took over the project but unfortunately they never finished it.
Version 0.2 the second draft written in the beginning of 2023.
Version 0.3 the first complete draft, end of May 2023.
Version 1.0, the first complete version after peer-review; June 2023.
Version 1.1, added a section on wet rock in Ethics, a section on quickdraws, a section on the clove hitch and munter hitch, plus some fixed some minor errors typos; April 2024.
Version 1.2, removed the section on clove and munter hitch, cleaned the sections about cleaning the anchor to follow the Petzl infographics, added more videos; January 2025.

thanks for reading!

Thanks to Vincent, Sammy, Austin, Pepijn, Saskia and Jordan

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