Description
Harken 57mm Black Magic Block | Boat Supply Store
Engineered for demanding sail control applications, this Harken block significantly reduces friction in high-performance systems. Its 57mm sheave diameter handles lines up to 12mm (7/16in) with a substantial 716kg (1655lbs) maximum working load. The integration of Torlon® roller bearings ensures exceptionally smooth operation, even under intense load, making it a critical component for serious offshore racing or cruising applications on vessels navigating the Gulf Coast.
Key Features
- Minimize friction with advanced Torlon® roller bearings.
- Handle substantial loads up to 716kg (1655lbs).
- Enhance line management via swiveling shackle to prevent twist.
- Benefit from lightweight aluminum construction for reduced weight aloft.
- Achieve optimal control with a 57mm sheave diameter.
- Ensure durability with 316 stainless steel shackle construction.
- Identify low-load configurations with distinctive red isolators.
- Accommodate lines up to 12mm (7/16in) for versatile rigging.
Specifications
| Product Specifications | |
|---|---|
| Sheave Diameter | 57mm |
| Length | 119mm |
| Weight | 154g |
| Shackle Pin | 6mm |
| Maximum Line Diameter | 12mm (7/16in) |
| Maximum Working Load | 716kg (1655lbs) |
| Breaking Load | 1500kg (3300lb) |
| Bearing Type | Torlon® roller bearings |
| Shackle Material | 316 Stainless Steel |
Who This Is For
Performance-oriented sailors, including big boat racers and cruisers, who require reliable and efficient sail control hardware. Ideal for those needing robust solutions for high-action systems such as mainsheets, runners, halyards, and spinnakers.
How It Compares
| Feature | Harken 57mm Black Magic Block | Competitor |
|---|---|---|
| Sheave Diameter | 57mm | — |
| Maximum Working Load (MWL) | 716kg (1655lbs) | — |
| Bearing Type | Torlon® roller bearings | Composite bearings |
| Shackle Material | 316 Stainless Steel | Stainless Steel |
Common Concerns Answered
Why is this block more expensive than some basic options?
The higher price point reflects the advanced engineering and premium materials, such as Torlon® roller bearings and 316 stainless steel, which provide superior durability and significantly lower friction, translating to better performance and longevity for demanding sailing applications.
Will a larger sheave be better for my specific needs?
While this 57mm sheave is optimized for a broad range of high-load applications, larger sheaves are generally beneficial for very heavy loads or specific types of lines that require a larger bend radius to prevent chafe or maximize efficiency. Consider your primary line diameter and load requirements for optimal selection.
How does the 'Low Load' designation impact performance?
The 'Low Load' designation, indicated by red isolators, signifies that this block is specifically engineered for applications where the load is distributed across multiple blocks or where exceptional friction reduction is paramount, even at moderate loads, ensuring smooth and efficient sail trim.
Frequently Asked Questions
What is the maximum line diameter this Harken block can accommodate?
The Harken 57mm Aluminum Low Load Black Magic Block is designed to accommodate lines with a maximum diameter of 12mm (7/16in).
What is the maximum working load for the Harken 57mm Low Load Black Magic Block?
The maximum working load for this block is 716kg (1655lbs).
What are Torlon® roller bearings and why are they used in this block?
Torlon® is a high-performance thermoplastic known for its exceptional strength, stiffness, and low friction properties. In this block, Torlon® roller bearings are used to dramatically reduce friction, allowing for exceptionally smooth operation and easier sail control even under high loads.
What is the difference between Harken's 'Low Load' and 'Standard' blocks?
Harken 'Low Load' blocks are specifically optimized for reduced friction and often incorporate features like roller bearings and lighter construction, ideal for systems where efficiency is critical. 'Standard' blocks offer robust performance for general-purpose use, but may not achieve the same level of friction reduction or lightweight design.
Can this block be used for mainsheet, runner, halyard, and spinnaker systems?
Yes, this block is suitable for mainsheet, runner, halyard, and spinnaker systems, particularly on performance-oriented boats where efficient and low-friction sail control is a priority.
