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Harken 2631 57mm Carbo Air Quadruple Block with Swivel

Manufacturer

Harken

<h3>About Harken: Performance Marine Hardware Since 1967</h3><p><strong>Harken</strong> is one of the most recognized names in performance marine hardware, with a legacy stretching back to 1967. <a href="/14853-harken">Harken</a> was founded in a 60-foot trailer by brothers Peter Harken and Olaf Harken, who set out to engineer better sailboat hardware than anything the market had to offer. Their early breakthrough — the plastic recirculating ball bearing block — redefined how sailors managed lines under load and launched a brand that would go on to dominate competitive sailing at the highest levels.</p><p>Headquartered in Pewaukee, Wisconsin, and with a major manufacturing facility in Limido Comasco, Italy, Harken operates as an employee-owned company with distribution spanning 48 countries. From club racing dinghies to grand prix offshore programs, Harken hardware has been aboard winning boats for decades — making its Olympic and America's Cup debuts in 1976 and 1977, respectively.</p><h3>A Full Range of Marine Hardware</h3><p>Harken's product lineup is broad by design. The company works hard to be the technological leader in sailboat blocks, deck hardware, winches, and hydraulics, as well as safety and rescue equipment and services. Their marine catalog includes small boat and big boat blocks, travelers and genoa leads, mainsail and headsail handling systems, winches, hydraulics, mooring solutions, and a robust line of spare parts and accessories.</p><p>At the core of it all are Harken's renowned <a href="/14853-harken-pulleys-blocks-200822">Pulleys &amp; Blocks</a> — the product category that started it all. Whether you're outfitting a high-tech racing dinghy or a bluewater cruising yacht, Harken blocks are engineered for high-load capacity, corrosion resistance, and the smoothest possible operation. The lineup spans sheave sizes from 16 mm all the way to 75 mm, with single, double, triple, fiddle, and soft-attach configurations to cover virtually every application on deck.</p><p>Beyond sailing, Harken also produces a dedicated line of sportfishing <a href="/14853-harken-pulleys-blocks-202394">Pulleys &amp; Blocks</a> engineered for the unique demands of offshore fishing. These compact, high-load pulleys are built for outrigger systems, dredge rigging, and heavy-duty line management — bringing the same patented bearing technology that excels on race courses to the rigors of the fishing cockpit.</p><h3>Why Sailors Trust Harken</h3><p>What sets Harken apart is a relentless commitment to engineering. Each product category is developed with input from top sailors, sailmakers, and boat designers — and the results speak for themselves on race courses worldwide. Harken hardware is a consistent fixture on America's Cup campaigns, Volvo Ocean Race fleets, Olympic classes, and everything in between. For cruisers, that race-proven performance translates into gear that is more reliable, longer-lasting, and more responsive than the alternatives.</p><ul><li>Employee-owned company with decades of marine engineering expertise</li><li>Manufacturing in the USA and Italy, with global distribution in 48 countries</li><li>Patented bearing systems engineered for high loads and minimal friction</li><li>Product lines covering everything from small dinghies to superyachts</li><li>Trusted at the Olympic Games and America's Cup since the 1970s</li></ul>

Part Number

2631
07/13/2036 3:47 AM
Sale Price

$173.19

In Stock (5)

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Product Details

The Harken 2631 57mm Carbo Air® Quadruple Block is a high-performance sailing block engineered for demanding sheet and purchase system applications. Part of Harken's trusted Carbo Air® line, this quad block delivers an exceptional strength-to-weight ratio in a compact, low-profile package—making it a go-to choice for racers and cruisers alike.

Carbo Air® Construction:

  • Sideplate material: Glass-fiber reinforced nylon resin, densely packed with long-glass fibers for maximum rigidity and durability
  • 60% stronger and 30% lighter than traditional Classic blocks
  • Ball bearings, sheave, and sideplates are UV-stabilized with carbon black for long-term sun and weather resistance
  • Delrin® ball bearings enable free-spinning sheave rotation even under heavy load

Key Specifications:

  • Sheave diameter: 57 mm (2-1/4 in)
  • Overall length: 121 mm (4-3/4 in)
  • Maximum line diameter: 10 mm (3/8 in)
  • Safe working load (SWL): 2,380 lb (1,080 kg)
  • Breaking strength: 5,000 lb (2,270 kg)
  • Shackle pin diameter: 6 mm
  • Weight: 12 oz (340 g)

Swivel & Locking System:

  • Features a 3-Way U-Lock system allowing the shackle to lock in front or side positions, or swivel freely to prevent line twist
  • Swivel head keeps lines running fair across varying lead angles

The Harken 2631 is ideal for mainsheet systems, jib sheets, and multi-purchase purchase systems on centerboard dinghies, keelboats, and catamarans. It is particularly well-suited for building a 10:1 mainsheet purchase system on dinghy catamarans. Compatible with main and jib sheet applications on boats such as Lightnings, Dragons, Solings, and J/24s.

Products specifications

Diameter

7/16 Inch or 11 mm

Length

4 3/4 Inches

Mount Type

Swivel Shackle

Type

Quad

Ball Bearings

Plastic

Becket

No Becket

Direction

Any

Integral Cleat

No Integral Cleat

Ratchet

Non Ratcheting

Safe Working Load

2380 Pounds

Sheave Diameter

57 mm

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