Specifications for Harken 75mm Black Magic Air Double Footblock with Lockoff
| Fastener Ø (mm) | 8 FH |
| Length (mm) | 111 |
| Recommended line - Max Ø (mm) | 14 |
| Sheave Ø (mm) | 75 |
| Height (mm) | 57 |
| SWL (kg) | 1572 |
| NBL (kg) | 3143 |
| A (mm) | 11.5 |
| B (mm) | 28.5 |
| C (mm) | 70.5 |
| D (mm) | 21 |
| E (mm) | 77 |
| F (mm) | 110 |
| G (mm) | 17 |
| Weight (g) | 574 |
Harken 75mm Black Magic Air Double Footblock with Lockoff
Twin-line deck deflection with integrated temporary sheet control
The Harken 75mm Black Magic Air Double Footblock with Lockoff combines efficient line deflection with smart control functionality, allowing sailors to temporarily secure lines directly at the deck. Designed for two independent 14mm lines, this block features a Safe Working Load (SWL) of 1572kg and a Breaking Load of 3143kg, making it ideal for use on performance yachts where both line management and on-deck accessibility are priorities.
Dual-Sheave Deck Routing
This double footblock is designed to redirect high-load lines such as headsail sheets, mainsheet returns, or halyard tails. The fixed base provides secure, low-profile mounting on deck, with separate 75mm sheaves for clean, efficient line handling.
⚠️ Note: As with all footblocks, effective working load will vary depending on line lead angle, and installation should be planned accordingly to ensure optimal performance.
Integrated Lockoff – Sheet Control at Your Feet
One of the standout features of this model is the lockoff mechanism, which acts as a temporary jammer—allowing you to secure a sheet or control line directly in the block without returning it to a winch or cleat. This is particularly valuable for:
- Temporarily holding headsail sheets while furling
- Managing control lines during manoeuvres
- Simplifying solo or shorthanded line handling
It enhances safety and efficiency by reducing the need for immediate winch tension and providing a hands-free moment to manage other tasks.
Advanced Bearing and Sheave Design
Each sheave rides on Torlon® roller bearings aligned by a precision centre cage, ensuring low-friction operation even under load. Delrin® side-load ball bearings manage lateral forces and are captive for secure, maintenance-friendly servicing.
Built for Harsh Marine Conditions
The sideplates and sheaves are Hard Lube-anodised, delivering maximum UV resistance, abrasion protection, and a smooth, low-friction surface that extends the block’s working life and maintains its high-gloss black finish.
Hidden Fastener Mounting
Designed for a clean installation, the block mounts using either metric or imperial flathead fasteners (not included), which are fully concealed once the block is installed—preserving aesthetics and preventing snagging on deck.
Specifications:
- Sheave Diameter: 75mm (x2)
- Maximum Line Diameter: 14mm
- Safe Working Load (SWL): 1572kg
- Breaking Load: 3143kg
- Configuration: Double Footblock with Lockoff
The Harken 75mm Black Magic Air Double Footblock with Lockoff offers a powerful combination of dual-line redirection and on-deck line control, making it an essential addition to the deck layout of modern racing and performance cruising yachts.
Specifications
| Fastener Ø (mm) | 8 FH |
| Length (mm) | 111 |
| Recommended line - Max Ø (mm) | 14 |
| Sheave Ø (mm) | 75 |
| Height (mm) | 57 |
| SWL (kg) | 1572 |
| NBL (kg) | 3143 |
| A (mm) | 11.5 |
| B (mm) | 28.5 |
| C (mm) | 70.5 |
| D (mm) | 21 |
| E (mm) | 77 |
| F (mm) | 110 |
| G (mm) | 17 |
| Weight (g) | 574 |
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