Sea Sure

SeaSure 25mm Double Block w/Becket

SKU: 100424
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02 · Overview

SeaSure 25mm Double Block w/Becket — Product description

The SeaSure 25mm double block with becket is one of their oldest, best-selling sailing blocks, and it earns that spot. Marine-grade stainless side plates, an Arnite plastic sheave on a plain bearing, and a becket so you can dead-end a line and build real purchase. Handles rope up to 8mm with a 1000kg breaking load.

If you've rigged a dinghy or a small keelboat, you already know these little SeaSure blocks. The 25mm plain-bearing range has been around forever because it just works. Stainless steel side plates and rivets, an Arnite plastic sheave that's hard-wearing and light, and a becket on the bottom cheek so you can tie off the standing end of your line.

That becket is the whole point of this one. It lets you dead-end a line right at the block, so you can build a 4:1 or 5:1 purchase without adding another block. Handy for kicking straps, outhauls, cunninghams, and cabin-top control lines where you need mechanical advantage in a tight spot.

It takes rope up to 8mm and carries a 1000kg breaking load, so it isn't just a sailing part. Folks reach for these on lifting rigs, garage-door setups, and light hoisting jobs too. The plain bearing is happiest under steady load rather than fast, repeated sheeting, but for control lines it runs smooth and lasts.

Key Features

  • Becket on the bottom cheek lets you dead-end a line and build a 4:1 or 5:1 purchase without a second block
  • Arnite plastic sheave on a plain bearing runs smooth under load and shrugs off UV and salt
  • Marine-grade stainless steel side plates and rivets stand up to a wet, salty life on deck
  • Takes rope up to 8mm with a 1000kg breaking load, enough for control lines and light hoisting
  • Compact 25mm sheave keeps weight and clutter down on dinghies and small keelboats

Why Buy from NVN Marine

  • Authorized Sea Sure reseller, full manufacturer warranty
  • NMEA member and ABYC certified, advice from real boat techs
  • Same-day shipping before 3 PM ET on in-stock items
  • NY headquarters and Fort Lauderdale flagship retail store
NVN Marine — 11 W State Road 84, Fort Lauderdale, FL 33315 Not available for local pickup $24.99
03 · The numbers

Technical specifications

Title SeaSure 25mm Double Block w/Becket
Brand Sea Sure
Manufacturer Part Number 00.23CRD
UPC 5036830090237
Sheave Diameter 25mm
Block Type Double block with becket
Bearing Type Plain bearing
Sheave Material Arnite plastic
Side Plate Material Marine-grade stainless steel
Rivet Material Marine-grade stainless steel
Maximum Rope Diameter 8mm
Breaking Load 1000kg
Product Range 25mm Plain Bearing Blocks
04 · Before you buy

Frequently asked questions

What's the becket for?

It's the small loop on the bottom cheek of the block. You tie the standing end of your line to it, which lets you build a 4:1 or 5:1 purchase off a single block instead of adding another one.

What size rope does it take?

Up to 8mm. SeaSure lists a 1000kg breaking load for the block, so match your line and hardware to the loads you'll actually see.

Is the sheave a ball bearing or plain bearing?

Plain bearing. That means it's built for steady, high-load jobs like control lines and purchase systems rather than fast, repeated sheeting where a ball-bearing block shines.

What's the sheave made of?

An Arnite plastic sheave running in marine-grade stainless steel side plates. Arnite is light and hard-wearing, and the stainless holds up to salt water and spray.

Can I use it for jobs other than sailing?

Yes. With an 8mm rope max and a 1000kg breaking load, boaters use these for lifting rigs, hoists, and other light mechanical-advantage setups, not just running rigging.

05 · Customer voices

Customer reviews