Complete replacement mastheads and sheave assemblies for Seldén aluminium and carbon dinghy spars, each matched to a specific mast section and supplied with all fixings required for installation.
How to choose the right masthead
Every masthead in this collection is section-specific. There is no universal fit. Before ordering, identify your mast section designation. It is stamped near the mast foot or listed on your class measurement certificate. Ordering by boat class alone is not reliable, as some classes have been supplied with more than one section over the years.
For carbon masts, you also need to decide between internal and external halyard routing. Internal halyard mastheads route the main halyard inside the spar and are the more common choice on performance boats where a clean rig profile matters. External halyard versions are the correct replacement where the original rig was set up that way. Check your existing masthead before ordering.
The halyard purchase ratio is relevant for carbon section mastheads. The S2, S3/S4 and Orbis internal halyard mastheads can all be rigged with either a 1:1 or 2:1 halyard arrangement. If you are replacing a masthead and want to retain your existing halyard setup, confirm the ratio currently in use before fitting.
If only the sheave, pin or split ring has failed, you do not need a complete masthead. The Masthead Sheave Assembly is a more economical repair for aluminium spars. A carbon-specific sheave assembly fits S2, S3, S4 and Orbis headboxes.
What's in this collection
The aluminium section mastheads are complete assemblies supplied with masthead body, section adapter, two sheaves and rivets. They are available for the following untapered section designations: Cumulus (501-099-01), Gamma (501-099-03), Kappa (501-099-04), Epsilon (501-099-05), Lamda (501-099-06) and 2420 (501-099-11).
The carbon section mastheads are supplied with masthead body, adapter, sheave and rivets. Internal halyard versions are available for S2 (501-218-01), S3/S4 (501-218-03) and Orbis (501-218-05) sections. External halyard versions cover S3/S4 (501-218-04) and Orbis (501-218-06). The K1 Carbon masthead (501-218-08) is a dedicated assembly for that class, supplied with masthead, sheave and rivets.
The Masthead Sheave Assembly — Aluminium (504-360-01) is a replacement sheave, pin and split ring that fits all standard headboxes on aluminium dinghy spars. It is the correct first step when the masthead structure is sound but the sheave is worn or damaged.
Dinghy class applications
The K1 Carbon masthead (501-218-08) is the only class-specific product in this collection, built directly for the K1 class dinghy.
All other mastheads are selected by section rather than class. The Kappa, Cumulus, Epsilon and Gamma sections are widely used across club racing, youth and single-handed classes. The Lamda section appears on larger single-handed and two-handed dinghies. The 2420 section is associated with smaller youth and junior class spars.
Carbon S2, S3 and S4 sections are fitted to higher-performance and squad-level dinghies where weight and stiffness are priorities. The Orbis carbon section is found on more recent Seldén carbon rig builds at the top of competitive fleets.
