
Ronstan
Ronstan Series 45 Core Block Single/Swivel Halyard
- Full name
- RONSTAN SERIES 45 CORE BLOCK SINGLE/SWIVEL HALYARD
- Mfg part #
- RF44188
- UPC
- 9316800484669
- SKU
- 66604
$125.26 $139.18
Backorder: ships once restocked by the manufacturer. We’ll email you if there’s a delay.
🚚 Free shipping over $100 This item ships free.
30-day returns. Details
Secure checkout · prices verified at checkout
Genuine parts from authorized distributors. Questions? getboatparts@gmail.com
- 30-day returns
About this part
The Ronstan Series 45 Core Block Single/Swivel Halyard is a genuine Ronstan part (manufacturer part # RF44188, UPC 9316800484669) in our Blocks range under Sailing. It's currently on backorder. Order now to reserve the next shipment. Shipping weight is about 0.4 lb.
Manufacturer description
Series 45 Core Block - Single/Swivel Haylard
Core Blocks™ are a true all round solution. A tuned 2-stage bearing system provides excellent performance across the full working load range with an integrated thrust bearing feature and the resilience to handle high dynamic or static loads. Acetal sheave, alloy cheeks and stainless fixings complete the durable package. For reliability and a long service life, these blocks are the right choice for sheets, halyards and control line applications for cruising and racing.
Universal Bearing
Block cheeks are manufactured from the highest quality alloy for maximum strength. Material optimization and the cut-away design minimizes weight and allows easy fresh water rinsing of salt and debris from the bearings. Cheek design has been further styled with flaring at the block throat and reduced gap between the cheek and sheave, minimizing rope wear.
Features:
Core Blocks™ are a true all round solution. A tuned 2-stage bearing system provides excellent performance across the full working load range with an integrated thrust bearing feature and the resilience to handle high dynamic or static loads. Acetal sheave, alloy cheeks and stainless fixings complete the durable package. For reliability and a long service life, these blocks are the right choice for sheets, halyards and control line applications for cruising and racing.
Universal Bearing
- Dynamic and high static load performance
- The Ronstan Universal Bearing incorporates our proven 2-stage bearing system
- Stage 1 - Under moderate loads, Acetal ball bearings ensure minimum friction
- Stage 2 - Under heavy loads, where deformation of ball bearings alone would result in increased friction, a sliding Acetal bearing on a polished stainless steel race takes over, maintaining low friction performance
- Additionally the ball bearings are configured to act as a thrust bearing between the sheave and cheeks, preventing the sheave from rubbing on the cheeks and causing friction when the line lead in and out of the block isn’t perfect. Particularly important for cheek blocks
Block cheeks are manufactured from the highest quality alloy for maximum strength. Material optimization and the cut-away design minimizes weight and allows easy fresh water rinsing of salt and debris from the bearings. Cheek design has been further styled with flaring at the block throat and reduced gap between the cheek and sheave, minimizing rope wear.
Features:
- High dynamic and static load capacity
- Efficient 2-stage bearing system
- Ball bearings to counteract side thrust loads
- Class leading performance and sleek, contemporary styling
- Durable aluminium alloy cheek plates
- Central hub hole can be used as a becket take-off or tie-up point
- Incorporates a low profile swivel head fork
- Features a removable screw pin for attachment to padeyes
- Suitable for 12mm (1/2") diam. mast collar post
- Ideal for mainsheet, halyard and spinnaker sheet applications on boats to 10M (33')
- Various control line applications on larger yachts
- Alloy sheave models are available for use with wire
- Sheave: U.V. stabilised Acetal
- Cheek body: Aluminium Alloy
- Ball Bearings: High compression strength carbon black Acetal
- Shackle, head post & hub: Grade 316 stainless steel
Related parts

Ronstan
Ronstan Series 40 Orbit BB Double Block w/ Becket and
Part # RF48210
$100.10In stock

Ronstan
Ronstan Series 15 Ball Bearing Block, Double
Part # RF15202
$27.46In stock

Schaefer Marine
Schaefer Single Stainless Steel Block 60mm Sheave
Part # 705-05
$148.69In stock

Harken
Harken 16mm Forkhead Block
Part # 376
$26.85In stock