Description
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)
Estimate shipping
Refund Policy
Easy Returns
We've taken out the hassle of returning an item so you can shop with confidence. If you need to return an item, we'll provide you with a pre-paid UPS return label that you can print at home. The cost for using the label will be calculated and deducted from your refund.
To start a return, please contact us at sales@theyachtrigger.com. Items sent back to us without first requesting a return will not be accepted.
30-Day Return Policy
We have a 30-day return policy, meaning you have 30 days after receiving your item to request a return or exchange.
Eligibility for Returns
To be eligible for a return, your item must be in the same condition that you received it—unworn or unused, including tags, instruction manuals, warranty cards, and in its original packaging. You’ll also need the receipt or proof of purchase.
We reserve the right to refuse returns or assess additional fees at our discretion if:
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The merchandise is missing parts
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The item is not in new condition
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The return is beyond the accepted return dates
Return Shipping & Restocking Fees
Customers are responsible for return shipping.
If you request The Yacht Rigger to provide a shipping tag, the shipping cost will be deducted from your refund. No international return shipping labels will be provided.
A 3% restocking fee will apply.
No returns on final sale items.
Damages and Warranties
Please inspect your order upon receipt and contact us immediately if the item is defective, damaged, or if you received the wrong item.
Most items we sell are covered by manufacturers' warranties. If you experience difficulty with a product, please contact the appropriate manufacturer for assistance and troubleshooting help, or email us at sales@theyachtrigger.com. If your order was received via freight truck, you must notify us within 5 days.
Exceptions / Non-Returnable Items
Certain types of items cannot be returned, such as custom products and special orders. This includes cut line, wire, rope, and similar items that are customized to length. We also do not accept returns for hazardous materials, flammable liquids, or gases. Unfortunately, we cannot accept returns on sale items or gift cards.
Exchanges
The fastest way to ensure you get what you want is to request a return of the item you have. Once the return is accepted, you can make a separate purchase for the new item to ensure it is in stock.
European Union 14-Day Cooling Off Period
If the merchandise is being shipped to the European Union, you have the right to cancel or return your order within 14 days, for any reason and without justification. As above, your item must be in the same condition that you received it—unworn or unused, with tags, instruction manuals, warranty cards, and in its original packaging. You’ll also need the receipt or proof of purchase.
Refunds
We will notify you once we’ve received and inspected your return and inform you if the refund was approved. When processing a refund, no additional transaction fee is incurred; however, the original credit card transaction fee is not refunded.
If approved, you’ll automatically be refunded to your original payment method within 10 business days. Please allow some time for your bank or credit card company to process and post the refund. If more than 15 business days have passed since we’ve approved your return, please contact us at sales@theyachtrigger.com.
Return Policy Abuse
We reserve the right to refuse service to anyone suspected of abusing any policy of The Yacht Rigger.





