Seldén S20, S30 and S40 soft attachment blocks, A60 automatic ratchet blocks with soft attachment, soft shackles and the Optimist sheet block kit: lightweight, lashing-mounted blocks for dinghy control lines and sheets.
How to choose
Block size follows line diameter and load. The S20 (20 mm sheave) suits trim lines and light control lines up to 6 mm on smaller boats. The S30 (30 mm sheave) handles lines up to 8 mm, making it a practical choice for mainsheets and control lines on dinghies. The S40 (40 mm sheave) accepts lines up to 10 mm, suited to mainsheets and spinnaker systems on more performance-oriented boats.
Within each size, choose between an Acetal sheave and a stainless steel sheave. The Acetal version covers most racing applications. The stainless steel sheave variant, marked with a plus suffix (S20+, S30+, S40+), carries a higher safe working load. Specify the plus variant if you are working near the load limit of the standard block or want additional grip on the line.
For mainsheets where load varies and ratchet-assisted holding is useful, the A60 soft attachment ratchet block is the correct choice. Both the composite sheave A60 and the aluminium sheave A60+ accept lines up to 10 mm. The ratchet switches on automatically as load increases, with the switchover point adjustable using an allen key. The A60+ aluminium sheave provides more grip on finer lines; the composite sheave version is the more neutral general-purpose choice.
For Optimist sailors, the Plug & Play Sheet Block kit (404-101-70R) provides a ready-assembled solution using ø30 mm and ø40 mm blocks with ø3 mm Dyneema connecting loops and a snap shackle, with no separate sourcing or assembly needed.
The soft shackle (614-521R) is for lightweight temporary attachment of blocks, lines or fittings. At 85 mm long with a ø3 mm Dyneema core, it suits sheet-to-clew attachments, tack line attachments for asymmetric spinnakers, and similar applications where a steel shackle would add unnecessary weight or risk chafe damage.
What's in this collection
The S20 range covers lines up to 6 mm and includes a single block with Acetal sheave (402-101-60R), a single with Acetal sheave and 2 mm / 550 mm Dyneema lashing pre-fitted (402-101-62R), a complete kit variant (402-101-60-01R), an S20+ single with stainless sheave and lashing included (402-101-65R), and a double block with Acetal sheaves accepting lashing up to ø4 mm (402-101-61R).
The S30 range covers lines up to 8 mm and includes a single with Acetal sheave and 2 mm Dyneema lashing included (403-101-60R), a double with Acetal sheaves where 2 mm Dyneema lashing is recommended but not supplied (403-101-61R), and an S30+ single with stainless sheave and 2 mm / 550 mm lashing included (403-101-65R).
The S40 range covers lines up to 10 mm and includes a single with Acetal sheave (404-101-60R), a double with two 40 mm Acetal sheaves (404-101-61R), an S40+ single with stainless sheave (404-101-65R), and a single with a pre-fitted 180 mm tie-on attachment loop secured with Tie-on Inserts (404-101-66R).
The A60 soft attachment ratchet blocks are 60 mm automatic ratchet blocks that mount via soft attachment rather than a shackle, both accepting lines up to 10 mm. The A60 with composite sheave (406-350-54R) is the standard version. The A60+ with aluminium sheave (406-360-54R) provides more grip on finer lines. The ratchet switchover point is user-adjustable with an allen key on both variants.
The Opti Sheet Block Plug & Play Solution (404-101-70R) combines ø30 mm and ø40 mm soft attachment blocks with ø3 mm Dyneema loops and a snap shackle, accepting lines up to 8 mm. It is supplied ready to install.
The Soft Shackle (614-521R) is a ø3 mm Dyneema core loop, 85 mm in length, with a breaking load of 500 kg.
Dinghy class applications
The Optimist is the most directly referenced class in this collection. The Plug & Play Sheet Block kit is purpose-built for the Optimist sheeting system. The S30 and S40 single blocks are also listed for Optimist use, covering individual block replacement within the sheet system.
Across other classes, soft attachment blocks suit any application where a lashing-mounted block is preferred over a shackle fitting. This is common on high-performance dinghies and skiffs where saving weight and reducing snagging points is a practical priority. The S20 is well suited to trim and light control lines on smaller single-handed boats. The S30 and S40 cover mainsheet and spinnaker applications on larger dinghies. The A60 and A60+ soft attachment ratchet blocks are the appropriate choice for mainsheet applications where ratchet assistance is needed without a fixed shackle mounting point.
