For Small boat. Single Sheeve Mast size 1.5/8" - 2"
This is a cast aluminum internal-halyard masthead fitting (often referred to as a masthead insert or cap) designed to cap a tubular round aluminum mast. Key Characteristics & Identification:The Spigot / Base: The stepped round lower section is designed to slide directly into the top of an open hollow round mast tube. With an outside base diameter measuring approximately 2" and an inner lip/core dimension around 1 5/8", it fits a standard small-boat round aluminum extrusion (frequently found on vintage daysailers, dinghies, and small cruising monohulls or catamarans).The Sheave Box: The raised slot houses a single internal sheave for running a main halyard or jib halyard internally down the mast tube, exiting near the base.Cross Pin / Axle Hole: The small horizontal hole drilled through the cheeks of the casting holds the clevis pin or axle pin that supports the internal sheave.Fastener Provision: The small hole visible on the lower spigot collar is a fastening hole (typically for a blind rivet or self-tapping stainless steel screw) used to lock the casting securely into the top of the mast tube so it cannot twist or pull out under halyard tension.Because small builders frequently sourced generic spar hardware from common marine spar manufacturers (such as Dwyer, Kenyon, or local rigging shops) rather than stamping unique brand names into castings, matching it strictly by part number is difficult without knowing the exact boat builder. However, matching the 1 5/8" to 2" inside/outside diameter profile to your mast extrusion outer wall thickness will confirm a drop-in replacement if yours is missing or damaged.
For Small boat. Single Sheeve Mast size 1.5/8" - 2"
This is a cast aluminum internal-halyard masthead fitting (often referred to as a masthead insert or cap) designed to cap a tubular round aluminum mast. Key Characteristics & Identification:The Spigot / Base: The stepped round lower section is designed to slide directly into the top of an open hollow round mast tube. With an outside base diameter measuring approximately 2" and an inner lip/core dimension around 1 5/8", it fits a standard small-boat round aluminum extrusion (frequently found on vintage daysailers, dinghies, and small cruising monohulls or catamarans).The Sheave Box: The raised slot houses a single internal sheave for running a main halyard or jib halyard internally down the mast tube, exiting near the base.Cross Pin / Axle Hole: The small horizontal hole drilled through the cheeks of the casting holds the clevis pin or axle pin that supports the internal sheave.Fastener Provision: The small hole visible on the lower spigot collar is a fastening hole (typically for a blind rivet or self-tapping stainless steel screw) used to lock the casting securely into the top of the mast tube so it cannot twist or pull out under halyard tension.Because small builders frequently sourced generic spar hardware from common marine spar manufacturers (such as Dwyer, Kenyon, or local rigging shops) rather than stamping unique brand names into castings, matching it strictly by part number is difficult without knowing the exact boat builder. However, matching the 1 5/8" to 2" inside/outside diameter profile to your mast extrusion outer wall thickness will confirm a drop-in replacement if yours is missing or damaged.
