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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...
Harken ratchet vs. Ratchamatic blocks explained: how each engages, holding power, and when to choose a switchable ratchet or an auto Ratchamatic.
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...
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...