When sailors search for Harken blocks, they’re usually looking for one thing: efficient, reliable hardware that keeps control lines running smoothly under load. Harken has built a reputation for producing some of the most trusted sailing hardware in the world, and their Carbo Air block range sits at the centre of that reputation.
Within that wider range, the Harken Carbo Air T2 blocks stand out as one of the lightest and most innovative options available. Designed specifically for modern running rigging systems, the T2 Harken blocks combine extremely low weight with high working loads and minimal friction.
Whether you sail a performance dinghy, sportboat, or a lightweight cruiser-racer, the T2 Harken block range offers a compact solution for control systems such as vangs, travellers, cascades and sheet systems.
What Makes Harken T2 Blocks Different?
The key innovation behind the T2 Harken block range is the soft-attach design. Instead of using traditional metal shackles or head posts, the blocks are designed to be attached using high-strength line.
This approach brings several advantages:
- Reduced weight aloft
- Fewer metal parts to corrode
- Greater alignment with the load
- More flexible installation options
All T2 Harken blocks route the attachment line through the load-bearing centre of the block, which reduces loads on the sideplates and also acts as a safety backup in the system.
Because the block can align naturally with the direction of the load, friction is reduced and efficiency increases. This is particularly beneficial in cascading systems and control line purchases where smooth running is critical.
Lightweight Construction Without Compromise
Another defining feature of the T2 Harken block range is the composite construction.
The blocks are built using fibre-reinforced composite materials with composite sheaves that spin on Delrin® ball bearings with curved bearing races, creating a low-friction system that distributes load efficiently.
By eliminating metal shackles and rivets entirely, Harken created some of the lightest soft-attach blocks in their entire range.
The result is an impressive strength-to-weight ratio. For example:
- The 29mm T2 single block weighs only 12g
- The 40mm T2 single block weighs just 25g
- The 57mm T2 single block handles working loads of 359kg
This combination of strength and minimal weight is exactly why these blocks are so popular on modern performance boats.
The Three Core Sizes in the T2 Harken Blocks
The Harken T2 family is built around three main sizes: 29mm, 40mm and 57mm. Each size is designed for slightly different applications within a boat’s running rigging system.
29mm T2 Harken Blocks – Ultra-Light Control Systems
The 29mm T2 Harken blocks are the smallest in the range and are designed primarily for:
- Control lines
- Cascades
- Barber haulers
- Lightweight purchases
With maximum line diameters of 8mm and working loads suitable for small systems, these Harken blocks are commonly used on dinghies and sportboats where keeping weight down is critical.
The range includes:
- 29mm T2 Single Block
- 29mm T2 Double Block
These are perfect for compact purchase systems where space and weight savings are essential.
40mm T2 Harken Blocks – Versatile Performance Hardware
The 40mm T2 Harken blocks are among the most versatile in the range and are widely used in:
- Traveller systems
- Vang purchases
- Mainsheet cascades
- Control line systems
This size introduces several additional configurations beyond the standard single and double blocks:
- 40mm T2 Loop Block
- 40mm T2 Single Block
- 40mm T2 Double Block
- 40mm T2 Ratchamatic® Block
- 40mm T2 Traveller Block
The Loop Block is particularly popular because it uses a removable Dyneema loop for quick attachment and removal, making it ideal where blocks may need to be repositioned frequently.
57mm T2 Harken Blocks – Higher Load Systems
For sailors needing greater load capacity, the 57mm T2 Harken blocks provide significantly higher working loads while still maintaining the lightweight advantages of the T2 design.
These Harken blocks are often used in:
- Mainsheet systems
- Spinnaker sheets
- High-load purchase systems
The available configurations include:
- 57mm T2 Loop Block
- 57mm T2 Single Block
- 57mm T2 Double Block
- 57mm T2 Ratchamatic® Block
- 57mm T2 Ratchamatic® Block – 2× Grip
The 2× Grip Ratchamatic version delivers increased holding power (up to 20:1), giving sailors better control in strong wind conditions.
Automatic Ratchet Technology in a Lightweight Package
Harken’s Ratchamatic technology is not unique to the T2 range — it appears across several Harken block families — but the Carbo Air T2 versions represent one of the lightest implementations of this system available.
Ratchamatic blocks automatically switch between free-running and ratchet modes depending on line load. When the load increases, the ratchet engages automatically to provide additional holding power. As the load drops, the mechanism disengages so the line can run freely again.
This automatic operation offers two major advantages for sailors:
- Sheets run freely during manoeuvres such as tacks, gybes or mark roundings
- Additional grip is applied automatically once the load builds again
In practical terms, this reduces the effort required to hold loaded sheets without requiring the sailor to manually engage or disengage the ratchet.
Traditional ratchet blocks often add weight because of the internal mechanism. Harken’s engineers solved this in the T2 range by integrating the Ratchamatic system into the minimalist soft-attach T2 architecture, using fibre-reinforced composite sideplates and a simplified ratchet mechanism.
The result is a high-performance ratchet block that remains extremely lightweight, while still delivering significant holding power.
These lightweight Ratchamatic blocks are particularly well suited to:
- Dinghy mainsheet systems
- Spinnaker sheets
- Beach cat control systems
- Lightweight sportboat trimming systems
For sailors who want the convenience of automatic ratchet engagement without adding unnecessary weight to their rigging systems, the T2 Ratchamatic blocks provide one of the most compact solutions in the Harken block range.
Where T2 Blocks Fit in the Harken Block Range
Harken produces several different block families, each designed for different sailing applications.
The Carbo Air Harken blocks sit within the “small boat blocks” category and are designed to be:
- Lightweight
- High-strength
- Low friction
- Cost-effective
They complement Harken’s larger Big Boat blocks, which are designed for much higher loads on larger yachts.
Within the Carbo Air family itself, the T2 Harken blocks represent the most minimalist and lightweight option, thanks to their soft-attach design and reduced number of metal components.
Typical Applications on Sailing Yachts
Despite their compact size, Harken T2 blocks are incredibly versatile and appear in many areas of modern sailboat rigging.
Common applications include:
- Traveller control systems
- Mainsheet fine-tune purchases
- Boom vang cascades
- Barber haulers
- Spinnaker sheet systems
- Bridle systems
- Control line purchases
Because they are soft-attached, they are also popular in custom rigging setups, where the ability to splice or lash blocks directly into a system gives riggers greater flexibility.
Why Sailors Choose T2 Harken Blocks
There are many reasons why the T2 Harken block range has become a favourite among performance sailors:
Extremely lightweight construction
By removing unnecessary metal parts, the blocks achieve an excellent strength-to-weight ratio.
Efficient low-friction performance
Composite sheaves running on Delrin® ball bearings ensure smooth trimming and easy release.
Flexible soft-attach installation
Blocks can be lashed, spliced or loop-attached almost anywhere in the rigging system.
Compact, minimalist design
The open Carbo Air structure removes excess material while maintaining strength.
Wide range of configurations
With multiple sizes and options such as Loop blocks and Ratchamatic ratchet blocks, the range can be tailored to almost any control system.
A Modern Classic Harken blocks in Performance Rigging
For sailors looking for lightweight, efficient and reliable Harken blocks, the Carbo Air T2 range is one of the most versatile options available today.
From the ultra-compact 29mm control line blocks to the powerful 57mm Ratchamatic versions used in mainsheet systems, the T2 family offers solutions for a wide variety of running rigging setups.
For performance sailors who want to reduce weight, minimise friction and keep their control systems running smoothly, Harken T2 blocks remain one of the smartest upgrades you can make to your boat’s deck hardware.
If you have any questions about Harken blocks, please feel free to contact us and talk to one of our sailing experts or click below to see our full range:
and then Add to Home Screen.
Harken Blocks: Why the Carbo Air T2 Range Is a Favourite Among Performance Sailors