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Choose blocks and attachments rated for your loads to build efficient, low-friction systems. Learn how sheave size, bearings, and lashing or shackle attachment affect performance.
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Match your mainsheet system to mainsail area first, then choose the two-speed purchase ratio and confirm the line diameter. This guide sizes real Harken and Ronstan mainsheet systems by boat...
Ball-bearing blocks reduce friction for lines you actively trim; plain-bearing blocks carry higher loads with less maintenance. This guide compares both, with real specs from Harken Carbo, Ronstan Orbit, Selden...
Single blocks turn a line; doubles and triples stack sheaves to build purchase. Here is how sheave count sets mechanical advantage and working load, and how to pick the right...
Ratchet blocks add a one-way sheave that grips a loaded line so you can hold a sheet by hand, while plain blocks run free. Here is when you need holding...
Fiddle blocks pack two stacked sheaves into one compact block to build 2:1 or 4:1 purchase for mainsheets, vangs, and control lines. Here is how to size and choose one.
Choose a block by matching four things to the job: sheave diameter to line diameter, bearing type to how the block is loaded and how often it moves, working load...
The Ronstan Series 42 Outhaul Car (RC14241A) is a track-mounted outhaul car that attaches via a fixed 20mm stainless steel clew pin and rides on Torlon ball bearings along the...
The Lewmar 60mm HTX Single Block is a high-performance hybrid-bearing pulley built around a 60mm sheave, engineered for mainsheet, halyard, vang, and traveler control on cruising and racing sailboats roughly...
Harken blocks are precision-engineered sailboat pulleys that redirect control lines over low-friction sheaves, reducing the effort needed to trim sheets, halyards, and running rigging. The lineup spans sheave diameters from...
The Harken Carbo 29mm Double Fixed Head block (381) is a lightweight, 34g twin-sheave block rated for control lines up to 8mm (5/16") and a 299 kg (660 lb) working...
Harken ratchet vs. Ratchamatic blocks explained: how each engages, holding power, and when to choose a switchable ratchet or an auto Ratchamatic.
The Lewmar 60mm HTX Single Block Upstand is a high-performance, upstand-mounted deck block built for smooth, low-friction routing of 10–14mm control lines on cruising and performance sailboats. Its 60mm HTX...
The Ronstan Series 100 Lashing Orbit Block (RF109109A) is a single-sheave, 360-degree swiveling block rated for lines up to 12mm (1/2 in) with a stainless steel lashing bail, built for...
When do you reach for a single block, and how do you size it? Learn how one sheave redirects a line or adds simple purchase, and how sheave diameter, attachment,...
How do you pick a block that will not fail under load? Learn how blocks redirect running rigging and multiply purchase, and how Working Load Limit, sheave diameter, and bearing...
A ratchet block is a sailing block with a toothed sheave that spins freely when you trim and grips when you ease, cutting the load on your hands by roughly...
To choose the right sailboat block, match its safe working load to your peak line load, match the sheave to your rope diameter, and pick the bearing type (plain, ball,...
Ronstan blocks are the pulleys that route and redirect running rigging—sheets, halyards and control lines—with the least possible friction, and choosing the right one comes down to three numbers: the...
A purchase system multiplies your pulling force by running a line through a set of blocks, so a small effort controls a large load. Simple purchase systems use a single...
Ronstan Orbit blocks are Ronstan's high-performance block range, built around a two-stage bearing system and fibre-reinforced sheaves that deliver an exceptional strength-to-weight ratio. In practice this means they run with...
Harken Black Magic blocks are Harken's high-load, roller-bearing block line built for big-boat sailing, offering greater working-load capacity than the composite Carbo Series while staying fully serviceable. They combine a...
Ronstan Series 40 Orbit Blocks are high-load sailboat blocks with maximum working loads from 400 kg up to 1000 kg (HHL versions), built around a lightweight glass-fiber-reinforced nylon body and a two-stage...
The Ronstan Series 55 Orbit Ratchet is a 55 mm ratchet block offering both automatic and manual engagement modes, up to 20:1 holding power, and a lightweight 82 g build. Built...
Choose a Harken ratchet block by matching sheave size to your line load, then deciding between a switchable ratchet (you turn the grip on and off) and a Ratchamatic (auto-engages...
The Harken Power3 ratchet is offered in 57 mm and 75 mm sheave sizes; this guide covers the 57 mm block, offered in three interchangeable holding-power levels — 10:1 (Standard, Black), 15:1 (1.5x,...
If you love Selden and want to know which block to use, we will show you the various blocks and the recommended applications to choose which block to get based...