Ronstan RF25309 Triple Lashing Block 20mm – Ball Bearing Pulley
Optimise your rigging setup with the Ronstan RF25309 Triple Lashing Block 20mm—a compact, high-performance triple sheave pulley designed for low-load, high-speed control systems.
Part of Ronstan’s advanced lashing block range, this unit features three 20mm sheaves running on precision ball bearings, delivering exceptionally low friction and smooth operation—ideal for fast-moving control lines such as dinghy rigging, vang systems, and cascading purchases.
Constructed with a fibre-reinforced composite body, the RF25309 offers excellent strength while remaining ultra-lightweight, helping reduce overall rig weight and improve responsiveness. The lashing attachment system replaces traditional shackles, allowing flexible positioning, reduced metal-to-metal contact, and quieter operation.
Designed for modern sailing systems, this block is perfect for high-performance dinghies, keelboats, and control line systems where efficiency and weight savings are critical. Key Features
- Triple 20mm sheave design – increased purchase and control
- Ball bearing system – ultra-low friction and smooth running
- Lashing attachment – lightweight, flexible rigging setup
- Fibre-reinforced composite body – strong and lightweight
- Compact design – ideal for tight rigging layouts
- Corrosion-resistant construction – marine-ready materials
- Optimised for high-speed control lines – responsive handling Specifications
- Brand: Ronstan
- Model: RF25309
- Product Type: Triple lashing block / pulley
- Sheave Diameter: 20mm
- Number of Sheaves: 3
- B.L. (kg) 800
- M.W.L. (kg) 300
- Max. Rope diameter (mm) 6
- Bearing Type: Ball bearing
- Construction: Fibre-reinforced composite
- Attachment: Lashing (rope attachment)
- Use: Sailing control systems Ideal Applications
- Dinghy and skiff rigging
- Vang and outhaul systems
- Cascading purchase systems
- Lightweight control line setups
This block is ideal where multiple purchase systems are required in a compact, lightweight format. Why Buy from Barton Marine NZ?
- Trusted sailing hardware supplier
- Fast nationwide delivery
- Genuine Ronstan performance hardware
- Ideal for racing and cruising conditions Pro Tip
- Use Dyneema or Spectra lashings for maximum strength and minimal stretch
- Perfect for cascading systems to increase mechanical advantage
- Keep blocks clean and rinsed to maintain smooth bearing performance