Series 20 Single Block with Shackle Head
Ball bearing blocks deliver high performance and sensitivity for static and dynamic loads.
A smooth and efficient block is critical to the conversation between sailor and boat—especially for hand-held control lines. Ronstan designed the Series 20 to give dinghy and small keelboat sailors the feedback to detect subtle wind changes and sail as efficiently as possible. These light-weight blocks feature a durable, UV stable acetal sheave that runs smoothly on a two stage system of low friction bearings. Acetal ball bearings handle moderate loads for high efficiency. As forces increase ball bearings can become distorted; shy of distortion a plain acetal bearing running on a stainless steel race shoulders the load keeping the ball bearings safe from damage while maintaining low friction. Fiber reinforced nylon cheeks provide rigidity and strength and are beefed up 316 stainless steel load straps. The included shackle features a pin with a low-profile head to prevent snagging on smaller lines. Get the subtle messages your boat sends you though the lines by using efficient and smooth Ronstan series 20 blocks.
This 20mm single with shackle head is versatile and can be used for a wide range of applications. Great for halyard tuners, Cunninghams, dinghy sheets and more.
- Light weight blocks designed for moderate to high static and dynamic loads
- Ideal for hand-held control lines
- Unique two stage bearing system:
- Acetal ball bearings deliver efficiency for moderate loads
- Sliding acetal bearing on stainless steel race handles high loads and maintains low friction
- Fiber reinforced nylon cheeks to add strength while reducing weight
- UV stable acetal sheave is strong and light-weight
- 316 stainless steel load straps add strength
- Ideal for:
- Dinghy sheets
- Halyard tuning systems
- Backstay systems on dinghies and smaller keelboats
- Boom vangs (cascade systems)
Ronstan Selection Guide
|Sheave Diameter||Line Compatibility||Shackle Pin Diameter|
Series 20 Single Block with Shackle Head
|Ball Bearings||Stainless Steel|
|Diameter||1/4 Inch or 6 mm|
|Integral Cleat||No Integral Cleat|
|Mount Type||Swivel Shackle|
|Safe Working Load||550 Pounds|
|Sheave Diameter||20 mm|
The West Advisor articles have answered boaters' questions and provided solutions to boating problems for more than 20 years. West Marine has compiled one of the Web's most comprehensive collections of technical boating information articles.
Related West Advisor Articles
To receive your order by December 24th, 2018, please reference the 2018 Holiday Shipping Schedule.
FREE DELIVERY to West Marine Stores
- Available for ALL products including hazardous & truck freight items.
- Ship to over 240 U.S. store locations.
- Contiguous United States orders arrive in 7 - 10 days.
- Hawaii and Alaska orders arrive in 10 - 16 days.
- Expedited shipping is available for an additional fee.
- Not available in Puerto Rico.
FREE SHIPPING on orders over $49.00
- Applicable on orders over $49.00 within the 48 contiguous United States.
- Does not apply to Truck Freight.
- No coupon code required.
- Orders will be delivered within 3 - 7 business days.
We stand behind everything we sell. If at any time your West Marine purchase does not meet your expectations, you can return it for a replacement or refund. If you are a West Advantage Rewards member, you don't even need a receipt - we'll have a record of your purchase. Returns can be made via mail or in person at their nearest store location. If you are not a West Advantage Rewards member, we will first need to verify your purchase by receipt or other method.
We do carry a few items that cannot be returned. This includes: items with expiration dates that have expired such as flares, charts, annual publications; items registered to the user such as boats, motors, EPIRBs, PLBs, SPOT, Class B AIS, life rafts; customized items such as rigging, and boat covers, computer software and electronics charts. Other non-returnable items include carry-on air conditioners, generators and select electronics. We will help you contact the vendor for assistance or repair on product that cannot be returned to West Marine. Items containing hazardous material may only be returned to a West Marine store.
Standard Shipping (ground service) is used to ship items that are considered hazardous. Estimated delivery is 3 – 7 business days and only applicable on deliveries within the contiguous United States. Signature Required for receipt of shipment.
For additional inquiries, you may call Customer Service at 1-800-BOATING (262-8464).