The complete Seldén block range for dinghies and keelboats, plain bearing, ball bearing, high load, fiddle, ratchet and soft attachment blocks from 16 mm to 60 mm sheave diameter, with single, double, triple and fiddle configurations across the BBB, PBB and S-series ranges.
How to choose
The right block for any application depends on four things: sheave size, bearing type, sheave count and attachment. Getting these right means the block works efficiently and lasts. Getting them wrong means friction, wear or a fitting that does not suit the job.
Sheave size follows line diameter. Smaller sheaves create more friction on thicker lines and wear lines faster. As a guide: 16–20 mm sheaves suit lines up to 6 mm for light applications. 25–30 mm sheaves suit lines up to 8 mm for mid-weight control lines and mainsheets on smaller dinghies. 40–60 mm sheaves suit lines up to 10 mm for mainsheets, spinnaker sheets and higher-load systems on two-handed boats and keelboats.
Bearing type follows load character. Plain bearing (PBB) blocks are suited to heavy, slow-moving or static loads, halyard tuning, boom vangs and kicker tackles where the line moves infrequently. Ball bearing (BBB) blocks are the correct choice for dynamic loads where the line runs frequently and friction needs to be minimised. High load BBB25 blocks are a specialist option with all-stainless construction for compact, high-load applications with wire or rope up to 5 mm. Ratchet blocks, available in manual (R60) and automatic (ARB45, A60) versions, are suited to mainsheets and spinnaker sheets where holding the line without cleating is needed.
Sheave count determines purchase ratio. A single block redirects a line. A double block provides a 2:1 purchase when combined with a second block. A triple provides 3:1 or higher. A fiddle block combines a large and a small sheave in one body, creating a compact purchase system without needing two separate blocks, useful where space is limited. The linked BBB30/BBB40 block combines a 40 mm and 30 mm sheave in one unit for versatile rigging options where two different line diameters need to be accommodated.
Attachment type must match your fitting point. Swivel blocks suit variable lead angles. Strap and fixed-pin blocks suit fixed attachment points. Tie-on blocks give an articulating, lightweight fit lashed to a boom or mast base. Cheek blocks mount flush to the deck for turning lines. Soft attachment (S-series) blocks use a Dyneema lashing or soft shackle instead of a shackle, saving weight and reducing snagging points.
Add a becket when the standing end of a purchase system anchors to the block. Add a cam cleat variant to lock the line off without a separate cleat fitting. A stand-up spring keeps a deck-mounted block upright and ready when the line is unloaded.
What's in this collection
This is the master collection covering all Seldén blocks. Dedicated sub-collections group blocks by sheave count and type for easier browsing when you already know what you need. The ranges covered are plain bearing singles (PBB16 and PBB20), ball bearing singles (BBB20, BBB30, BBB40, BBB60), soft attachment singles and doubles (S20, S30, S40), high load blocks (BBB25), double ball bearing blocks (BBB20 through BBB60), triple ball bearing blocks (BBB20 through BBB60), fiddle blocks (PBB40, BBB40, BBB60), ratchet blocks (R60 manual and ARB45/A60 automatic), the Optimist Plug and Play sheet block kit, and the stand-up spring for deck-mounted BBB40 blocks.
Fiddle blocks are available in the BBB40 and BBB60 ball bearing ranges and the PBB40 plain bearing range. A fiddle block has a large primary sheave and a smaller secondary sheave in a single body. The BBB40 fiddle range covers lines up to 10 mm and is available as standard, becket, cam and becket cam variants, all with swivel shackle locking at 0° or 90°. A specialist BBB40 fiddle hook cam eye variant (404-101-19R) adds a hook for quick attachment and an eye on the cam cleat arm for cascade dead-end use. The BBB60 fiddle range also covers lines up to 10 mm with a 38 mm cam cleat on cam variants. The PBB40 fiddle swivel (404-001-11R) suits static and heavy loads up to 8 mm.
The BBB40 linked block (404-101-21) pairs a 40 mm and 30 mm sheave in a single unit for applications where two different line diameters run through the same fitting point.
The BBB60 cheek flat base blocks mount to deck or coaming surfaces for leading lines over deck. The standard version (406-601-15R) and heavy duty version (406-601-65R, with stainless ball bearing races and Acetal bearing cages) both suit lines up to 10 mm.
The stand-up spring (433-411R) is a stainless steel spring that holds a deck-mounted BBB40 block upright when the line is slack, keeping it ready for use without needing to be repositioned.
