Ronstan
Ronstan RF25209 Double Lashing Block 20mm – Ball Bearing Pulley
Enhance your sailing performance with the Ronstan RF25209 Double Lashing Block 20mm—a lightweight, high-efficiency double sheave pulley designed for modern control line systems.
Part of Ronstan’s advanced Series 20 range, this block features dual 20mm acetal sheaves with a 2-stage ball bearing system, delivering exceptionally low friction and smooth operation under both dynamic and static loads.
Engineered for performance sailing, the RF25209 offers an outstanding strength-to-weight ratio, with a maximum working load of 300kg and breaking load of 800kg, while weighing just around 14g—making it ideal for weight-sensitive applications.
The lashing attachment system replaces traditional shackles, allowing for flexible rigging configurations, reduced weight, and quieter operation. The central hub enables secure lashing using Dyneema or Spectra, ensuring strong and adaptable mounting options.
Constructed with toughened nylon cheeks and high-strength composite materials, this block is built to withstand harsh marine environments while maintaining long-term reliability and performance.
Key Features
- Double 20mm sheave design – increased purchase capability
- 2-stage ball bearing system – ultra-low friction performance
- Lightweight (approx. 14g) – ideal for performance rigs
- High load capacity (300kg MWL / 800kg BL)
- Lashing attachment system – flexible, lightweight rigging
- Composite construction – corrosion-resistant and durable
- Compact design – suits tight rigging layouts
Specifications
- Brand: Ronstan
- Model: RF25209
- Product Type: Double lashing block / pulley
- Sheave Diameter: 20mm
- Number of Sheaves: 2
- Bearing Type: Ball bearing (2-stage system)
- Max Rope Diameter: 6mm
- Maximum Working Load: 300kg
- Breaking Load: 800kg
- Weight: Approx. 14g
- Construction: Toughened nylon cheeks, acetal sheaves
- Attachment: Lashing (rope attachment)
Ideal Applications
- Dinghy and skiff control systems
- Vang and outhaul setups
- Cunningham and traveller systems
- Cascading purchase systems
- Kite and spinnaker control lines
This block is ideal where you need medium purchase power with minimal weight and maximum efficiency.
Why Buy from Barton Marine NZ?
- Trusted NZ sailing hardware specialist
- Fast nationwide delivery
- Genuine Ronstan performance gear
- Ideal for NZ racing and cruising conditions
Pro Tip
- Use Dyneema lashings for maximum strength and minimal stretch
- Perfect for cascading systems to increase mechanical advantage
- Keep bearings rinsed with fresh water for long-term smooth performance
