Luff Tapes
Luff Tapes and Bolt Ropes
Section titled “Luff Tapes and Bolt Ropes”Standardized specifications for luff attachment systems used in both mainsails and headsails. These tapes serve as the interface between the sail edge and the mast groove or furling foil.
1. System Overview
Section titled “1. System Overview”Luff Tape (or “Bolt Rope”) consists of a rope core (usually pre-stretched polyester or polypropylene) enclosed in a fabric tape (Dacron or Kador). This assembly is sewn onto the luff of the sail.
Key Functions:
- Load Distribution: Distributes luff tension evenly along the mast/foil groove.
- Aerodynamics: Seals the gap between mast and sail for racing efficiency.
- Furling Interface: Essential for all headsail furling systems and in-mast/in-boom mainsail furling.
2. Dacron Tape Series (Standard)
Section titled “2. Dacron Tape Series (Standard)”Traditional construction using a rope core with a folded Dacron tape covering. Most common for mainsails and standard cruising headsails.
| Code | Construction | Finished Diameter | Typical Application |
|---|---|---|---|
| #4D | 1/8” rope (3.2mm) + Tape | 3.8 mm | Small boats, dinghy racing, storm jibs |
| #5D | 5/32” rope (4.0mm) + Tape | 4.7 mm | Boats 20-30ft |
| #6D | 3/16” rope (4.8mm) + Tape | 5.4 mm | Boats 30-35ft |
| #7D | 7/32” rope (5.6mm) + Tape | 6.3 mm | Boats 35-40ft |
| #8D | 1/4” rope (6.4mm) + Tape | 7.0 mm | Boats 40-45ft |
| #9D | 9/32” rope (7.1mm) + Tape | 7.8 mm | Large boats 45-50ft |
| #10D | 5/16” rope (7.9mm) + Tape | 8.6 mm | Heavy-duty 50ft+ |
Note: “Finished Diameter” is the critical dimension for fitting into mast grooves or furling foils.
3. Kador Tape Series (Modern)
Section titled “3. Kador Tape Series (Modern)”Modern luff tape system (often called “Keder”) featuring a monolithic or specialized extruded bead, offering superior finish, lower friction, and better UV durability.
| Code | Finished Diameter | Color Options | Typical Application |
|---|---|---|---|
| K 4.5 | 4.5 mm | White or Black | Boats 20-28ft |
| K 5.5 | 5.5 mm | White or Black | Boats 30-36ft |
| K 6.5 | 6.5 mm | White or Black | Boats 38-45ft |
| K 7.5 | 7.5 mm | White or Black | Boats 45ft+ |
Phasing Out:
- K 5 (4.7mm) -> Use K 5.5
- K 6 (5.7mm) -> Use K 6.5
4. Cutback and Finishing
Section titled “4. Cutback and Finishing”When used in mast grooves (Main) or Furling Foils (Headsail), the tape requires specific finishing:
- Cutback: The rope core is typically cut back 100-200mm from the Head and Tack to allow the sail corners to be tensioned/strapped without the rope interfering with the feed gate or drum.
- Floating Luff: The sail fabric floats independently of the rope, allowing cunningham/halyard tension to act on the cloth, not just the rope.
- Chamfer: The entry/exit point of the tape must be tapered/chamfered to ensure smooth feeding into the pre-feeder or groove.
5. Compatibility Guide
Section titled “5. Compatibility Guide”Furling Systems (Headsail):
- Profurl: Typically requires large diameter (e.g., #6D to #8D or K 6.5+).
- Harken: Varies by unit (Unit 0, 1, 2, etc.), often accepts a range (e.g., #5D or #6D).
- Selden Furlex: Specific groove tolerances, check manual (often #6D standard).
- Facnor: often accepts standard #5D/#6D.
Mast Grooves (Mainsail):
- Must measure the mast groove internal width and gate width.
- Bolt Rope Mains: Use the largest diameter that slides freely to prevent pull-out under load.