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

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    Sale Price $153.85 Regular Price $181.00
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    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)

    Product Specifications
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    Documents
    User Manual Download
    Specification Sheet Download
    Safety Guide Download
    Service & Support

    Warranty

    This product is backed by a 12-month limited warranty, covering defects in materials and workmanship under normal use.

    Technical Assistance

    Our dedicated support team is available to assist with product setup, operation guidance, and troubleshooting. Contact us via email or phone for prompt service.

    Documentation & Downloads

    Access essential resources including the user manual, technical specifications, and safety instructions in our online support center.

    Replacement Parts & Accessories

    We offer a full range of genuine replacement parts, including batteries, chargers, and compatible accessories to ensure long-term performance.

    Training & Tutorials

    Browse our library of how-to videos and maintenance tips to get the most out of your cordless drill.

    FAQs

    Find quick answers to common questions

    Product & Usage

    1. Is your gear authentic and warranty-backed?

    Yes — we are an authorized US dealer for 300+ marine electronics brands. Every order ships with the manufacturer’s full warranty.

    2. Are these products beginner-friendly?

    Yes. Our products are designed for both seasoned boaters and first-time owners. Each unit ships with a manufacturer manual, and we’re happy to answer setup questions over email.

    3. Are these products built for marine conditions?

    Yes. Marine electronics are engineered for saltwater spray, vibration, and weather. Check the product specs for IPX waterproof rating and saltwater certifications.

    Maintenance & Accessories

    1. What maintenance does marine electronics require?

    Rinse with fresh water after saltwater exposure, store in a dry place, and follow your manufacturer’s cleaning and storage instructions.

    2. Can I buy replacement parts and accessories separately?

    Yes — we carry replacement parts, mounts, transducers, cables, and accessories for the brands we stock.

    3. Do you provide product manuals or installation guides?

    Every product ships with the original manufacturer’s manual. Digital copies and detailed installation guides are typically available on the brand’s website.

    Warranty & Guarantee

    1. Does my purchase include a warranty?

    Yes — every order includes the full manufacturer warranty. Coverage length varies by brand (typically 1–3 years for Garmin, Lowrance, Raymarine, Simrad, Humminbird, Furuno, and others).

    2. How do I register for warranty coverage?

    Register directly with the manufacturer using your unit’s serial number. Manufacturer registration is the fastest path to warranty support if you ever need it.

    3. What does the manufacturer warranty cover?

    Defects in materials and workmanship under normal use. Damage from impact, improper installation, or saltwater corrosion (without protection) may be excluded. Check brand-specific terms in your unit’s documentation.

    4. Can I extend the warranty?

    Some manufacturers offer extended-coverage programs through their registration portals. We don’t sell third-party warranty programs.

    Purchasing & Support

    1. How fast does my order ship?

    Orders placed before 4pm EST Monday–Friday ship the same business day via UPS from our NJ or FL warehouses. Continental US delivery typically takes 3–7 business days for Economy.

    2. Do you offer bulk or fleet pricing?

    Yes — we offer volume pricing for fleet operators, marinas, dealers, and commercial customers. Email support@marineelectronicsdepot.com with your needs.

    3. How can I contact support?

    Email support@marineelectronicsdepot.com or call during business hours (Mon–Fri 9am–5pm ET). We’re happy to help with pre-purchase questions, order status, or post-sale support.

    Can’t find your answer?

    Feel free to reach out to us!

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