Ronstan Series 75 Core Block - Single [RF74100]
SKU: 89880949312

Ronstan Series 75 Core Block - Single [RF74100]

Sale price$138.47 Regular price$153.85
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Ships within 48 hours · Estimated delivery Jul 8 - Jul 13

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Description

Ronstan Series 75 Core Block - Single [RF74100]Series 75 Core Block Single 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

Series 75 Core Block™ - Single

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 optimisation and the cut-away design minimises 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, minimising rope wear.

Universal head
The head assembly incorporates a brass bearing washer to provide smooth 360™ rotation of the post and shackle. A set screw arrangement allows the head to be locked at 0™ or 90™.

Shackles are high quality forged grade 316 stainless steel.

Features:

  • Class leading performance and sleek, contemporary styling
  • Excellent dynamic and high static load performance
  • Less than half the friction of the nearest competitor
  • Universal head with full 3-axis articulation
  • Head posts can be locked at 0 or 90 degrees, by using a 2.5mm Hex/Allen Key
  • Central hub hole can be used as a becket take-off or tie-up point


Applications:
  • Ideal for mainsheet, halyard and spinnaker sheet applications on boats to 14M (46')
  • Various control line applications on larger yachts


Materials:
  • Sheave: U.V. stabilized Acetal
  • Cheek body: Aluminium Alloy
  • Ball Bearings: High compression strength carbon black Acetal
  • Shackle, head post & hub: Grade 316 stainless steel


Specifications:
Sheave Ø: 75mm(3")
Max. Rope Ø: 14mm(9/16")
Pin Ø: 8mm(5/16")
M.W.L.: 1,500kg(3,300lbs)
B. L.: 3,000kg(6,600lbs)
Weight: 354g(12.5oz)

Shipping Notes
  • Free Standard Shipping on $100+ Orders to the USA.
  • Except Preorder products are shipped in 48 hours.
  • Delivery to the USA:
  1. 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
SKU: 89880949312

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Carolyn Payne
New York, US
★★★★★ 4
Good but needs washing instructions inside shirt
Size: X-Large, Color: Light Green
Needs washing instructions & fabric content inside shirt otherwise a good shirt
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Reviewed in the United States on April 18, 2026
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Melissa
West Palm Beach, US
★★★★★ 5
Great purchase
Size: Large, Color: Blue Shark-white
Shirt was the perfect gift for my 21 year old son. The small pattern was perfect and he said that made the shirt cool. The material is comfortable and light enough for warm weather without feeling cheap. Shirt is versatile with the ability to dress up or down.
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Reviewed in the United States on April 9, 2026
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Tammy Nickles
Belleville, US
★★★★★ 5
Great quality
Size: XX-Large, Color: Grey Blue
Great quality! Very nice color! Fits to size.
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Reviewed in the United States on April 22, 2026
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Saúl Castillo
Massapequa, US
★★★★★ 5
Highly recommend
Is a great product, it fit perfectly, the materials are great.
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Reviewed in the United States on April 7, 2026
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jerseymca
Grantham, US
★★★★★ 4
Looks great
Size: Large, Color: Black
Looks great, comfortable to wear, love that the buttons are the same color as the shirt, easy to wash, appears to be durably made. Significantly exceeded expectations (I ordered 2 more). 4 stars instead of 5 because it’s possible to move your arms in a way that makes the shirt slightly tight in the bicep area, but that’s unnoticeable almost all of the time (and minor anyway). Note: even after a couple of wash - wear - wash cycles, there were creases along the same places as where the shirt was shipped; this was easily remedied by a quick iron on a low setting and I think reflects that it is quite resistant to wrinkles.
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Reviewed in the United States on February 26, 2025

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