Which knot to use on a carabiner for tree climbing?

Why is the carabiner's connecting knot so crucial in tree climbing?

In professional tree climbing, the choice of knot directly influences:

• The stability of the system;

• The carabiner alignment;

• Maintaining the load on the longer axle;

• Reducing the risk of cross-loading.

ABNT NBR 16246-2:2024 — Urban forests — Tree management,

Shrubs and other woody plants - Part 2: Safety requirements in services

In arboriculture, it establishes objective criteria on how the rope should be terminated and connected to the connecting element.

In items 10.1.9.1 to 10.1.9.3 , the standard states that:

• The rope must be terminated with a pre-fabricated eyelet or with a knot that interfaces appropriately with the connecting element;

• When the connector is not class T (according to ABNT NBR 15837), the termination must maintain the load along the main axis;

• The connection must be compatible to limit the possibility of accidental disconnection or loading on the carabiner's minor axis.

The standard does not impose a specific node. It imposes structural performance.

What does "appropriate interface" mean with the carabiner?

Technically, a proper interface implies that the node:

• Fit it securely onto the carabiner;

• Reduce excessive rotation;

• Avoid forming broad ties;

• Keep the load on the major axis;

• Limit the risk of loading on the minor axis.

  
  

If the knot allows excessive rotation of the connector, the structural risk increases — which may contradict the principles of the standard.

Some Knots Used

Based on professional practice and specialized technical literature, three knots are frequently used when the goal is stability in the connection to the carabiner.

1. Faithful Knot (Clove Hitch)

Nó Fiel com arremate pescador na corda Marlow

Common applications: quick adjustments, temporary positioning.

Advantages:

• Easy to perform;

• Allows for adjustment;

• It can be secured with a safety knot.

  
  

Important note: Under variable load, it may allow slight movement. It should be evaluated within a closed system. When used in an open system, a finishing knot is necessary.

2. Anchor Hitch

Nó âncora com arremate pescador na corda Marlow

Common application: more stable terminations.

Advantages:

• It fits snugly onto the carabiner;

• Reduces movement;

• It maintains better structural alignment;

• Excellent stability under load.

It is one of the most consistent knots when the goal is to limit rotation. When used in an open system, a finishing knot is necessary.

3. Double Fisherman's

Nó Pescador duplo corrediço com corda Marlow

Common application: forming loops.

Advantages:

• High resistance;

• Reliability under constant load;

  Although it is a very secure and stable knot, it is important to note that when subjected to high tension, it tends to compact significantly, making it difficult to untie after intense or prolonged loading.

Knot configurations that do not meet regulatory requirements.

Forma errada de se utilizar um nó como conexão.

Forma errada de se utilizar um nó como conexão.

Knots that form wide loops, such as the bowline knot or the figure-eight knot with a loop , allow for greater mobility of the carabiner within the termination.

This play can promote rotation of the connector and increase the risk of loading off the main axis.

Following ABNT NBR 16246-2:2024 , the termination must maintain alignment on the major axis and limit loading on the minor axis, which is why knots that do not fit firmly to the carabiner may not be the most suitable for this application.

Direct relationship with ABNT NBR 16246-2

Analyzing items 10.1.9.1 to 10.1.9.3, it can be observed that:

• The node must provide a suitable interface;

• The system must maintain the main axis;

• The connection should limit the load on the shorter axis.

Therefore, the choice of knot should be both technical and deliberate.

Want to learn this in practice?

At Arbolab, the Tree Climbing and Pruning course covers:

✔ Correct node selection for each application

✔ Structural analysis of the climbing system

✔ Practical interpretation of NBR 16246-2

✔ Secure connector configuration

✔ Risk assessment and prevention of cross-loading

👉 Learn not only how to tie the knot, but also how to understand the structural behavior of the system.

📌 Check the next class schedule on the Arbolab website.

WhatsApp: 15-3500-9995

References

Brazilian Association of Technical Standards (ABNT). ABNT NBR 16246-2:2024 — Tree work techniques — Part 2: Safety requirements. Rio de Janeiro: ABNT, 2024.

AMERICAN NATIONAL STANDARDS INSTITUTE (ANSI). ANSI Z133 — Safety Requirements for Arboricultural Operations. Atlanta: International Society of Arboriculture (ISA).

JEPSON, Jeff. Knots at Work: A Field Guide for the Modern Arborist. Beaver Tree Publishing.