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Description
Ronstan 75mm Mast Base Core BlockProduct Description Ronstan 75mm Mast Base Core Block Features Class leading performance and sleek, contemporary styling Excellent dynamic and high static load performance Less than half the friction of the nearest competitor Durable aluminum alloy cheek plates Central hub hole can be used as a becket take off or tie up point Suits attachment to 14mm (9 16) wide mast collar post Removable 8mm (5 16) clevis pin at head Measurements Sheave 3 in. Max.
Product Description
Ronstan 75mm Mast Base Core Block
Features
Class leading performance and sleek, contemporary styling
Excellent dynamic and high static load performance
Less than half the friction of the nearest competitor
Durable aluminum alloy cheek plates
Central hub hole can be used as a becket take-off or tie-up point
Suits attachment to 14mm (9/16”) wide mast collar post
Removable 8mm (5/16”) clevis pin at head
Measurements
Sheave Ø - 3 in.
Max. Rope Ø - 9/16 in.
Max. Cable Ø - in
Pin Ø - 5/16 in.
M.W.L. - 3000* lb.
B. L. - 6600* lb.
Weight - 8.1 oz.
Product Information
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.
Alloy cheek plates
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.
Applications
Ideal for use on mainsheet, spinnaker sheet, vang, halyard and backstay applications on boats up to 14m (46ft).
General applications on larger yachts.
Alloy sheave models are available for use with wire.
Materials
Sheave: U.V. stabilized acetal or anodized aluminum (AW models).
Cheek plates: Aluminum alloy
Ball Bearings: High compression strength carbon black acetal.
Pin: 2205 stainless steel
Features
Measurements
Sheave Ø - 3 in.
Max. Rope Ø - 9/16 in.
Max. Cable Ø - in
Pin Ø - 5/16 in.
M.W.L. - 3000* lb.
B. L. - 6600* lb.
Weight - 8.1 oz.
Product Information
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.
Alloy cheek plates
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.
Applications
Materials
Shipping Notes
- Free Standard Shipping on $100+ Orders to the USA.
- Except Preorder products are shipped in 48 hours.
- Delivery to the USA:
- Standard Shipping : 3-10 business days
- If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
- We offer a 30-day return/exchange service after receiving.
- Final sale items are not eligible for returns or exchanges.
- To process your return/exchange, please contact us at [email protected]
- Please click here for more details>>> Return & Exchange Policy
4.5 ★★★★★
Based on 8 reviews
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Product Reviews
★★★★★ 5
Don’t hesitate
Size: 15 FT, Style: 0 (1/0) AWG RED
Tough good quality wire!
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 5, 2026
★★★★★ 5
Buy them. You won't regret it.
Size: 10 FT, Style: 0 (1/0) AWG RED
Thick, flexible, quality cable. Overkill for what I've got but man they flex like wet noodles easy to run.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on October 21, 2025
★★★★★ 5
Quality.
Size: 15 FT, Style: 0 (1/0) AWG RED, Size: 15 FT, Style: 0 (1/0) AWG RED
If you’re reading this stop just get it.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 20, 2026
★★★★★ 4
slightly smaller than sky high
Size: 30 FT, Style: 0 (1/0) AWG RED
wire is okay but it is definitely on the thinner side, was slightly smaller than my sky high 1/0 wire but for the price difference this is definitely worth it
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on February 23, 2025
★★★★★ 5
Heavy gauge battery cable
Size: 10 FT, Style: 0 (1/0) AWG RED
Heavy duty works good
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on March 11, 2026