Luff Systems
Luff Attachment Systems
Section titled “Luff Attachment Systems”Mainsail luff-to-mast connection specifications, differentiating between Slide/Car systems and Bolt Rope systems.
1. System Selection: Slide/Car vs. Bolt Rope
Section titled “1. System Selection: Slide/Car vs. Bolt Rope”The primary decision for mainsail luff attachment is the system type.
| System | Description | Best For | Pros | Cons |
|---|---|---|---|---|
| Slide / Car | Sail attaches to mast via individual slides or cars | Cruising, larger boats, full-length battens | Low friction (cars), easy hoisting/dropping, reefing | Higher cost (cars), distinct point loads |
| Bolt Rope | Rope edge feeds directly into mast groove | Racing, dinghies, some furling systems | Aerodynamic, continuous load distribution, low cost | High friction, difficult to hoist/drop solo |
2. Slide & Car Systems
Section titled “2. Slide & Car Systems”When using slides or cars, the luff edge is finished with a Luff Rope (see section 3) to provide strength and a connection point.
A. Slides (Internal Groove)
Section titled “A. Slides (Internal Groove)”Slides fit inside the mast groove. They rely on the shape of the groove to stay attached.
| Feature | Specification |
|---|---|
| Mechanism | Sliding friction (plastic or metal on metal) |
| Installation | Fed into mast gate |
| Material | Nylon, Acetal (Delrin), or Stainless Steel |
| Cost | Low to Moderate |
| Vessel Size | Dinghies up to ~45ft cruisers |
Common Slide Types
Section titled “Common Slide Types”| Type | Description | Application |
|---|---|---|
| Flat Slug | Rectangular or flat profile | Older masts, external tracks |
| Round Slug | Cylindrical profile | Modern internal grooves |
| T-Slide | T-shaped profile | Specific metal mast tracks |
Key Brands: Bainbridge, Selden, Rutgerson.
B. Cars (External/Track)
Section titled “B. Cars (External/Track)”Cars run on an external track or specialized internal track. They use wheels or ball bearings.
| Feature | Specification |
|---|---|
| Mechanism | Rolling friction (wheels/bearings) |
| Installation | Requires track end stop removal; stays on mast |
| Material | Aluminum, Stainless Steel, Composite |
| Cost | High |
| Vessel Size | 40ft+, Full-Batten Mains, Performance Cruisers |
Common Car Types
Section titled “Common Car Types”| Type | Description | Application |
|---|---|---|
| Battcar | Carries batten compression load | Full-batten mainsails |
| Intermediate Car | Supports luff between battens | Stabilizes luff |
| Headboard Car | Supports main halyard load | All large mainsails |
Key Brands: Harken, Ronstan, Antal, Rutgerson (Pressure absorbers).
3. Luff Rope Specifications
Section titled “3. Luff Rope Specifications”Standard luff rope construction using rope core with Dacron tape covering.
For complete specifications on luff ropes and tapes (Dacron/Kador), including diameters and applications, see the Luff Tapes & Ropes module.
4. Bolt Rope Systems
Section titled “4. Bolt Rope Systems”In this system, the Luff Rope (as defined in Section 3) feeds directly into the mast groove. This is the primary attachment method for racing yachts and dinghies.
System Logic & Cutback
Section titled “System Logic & Cutback”Unlike a fixed slider system, the bolt rope interacts dynamically with the mast groove:
| Feature | Specification |
|---|---|
| Rope = Luff Rope | The “Bolt Rope” is simply the rope core inside the #4D-#10D luff tape. |
| Cutback | The rope core is cut back (shortened) at the Head and Tack (approx. 100-200mm). |
| Floating Luff | The cutback allows the sail fabric to be tensioned (Cunningham/Halyard) independently of the rope, which may shrink or have different stretch characteristics. |
| Reinforcement Slope | The luff tape/reinforcement at the cutback transition must have a tapered slope (chamfer) to feed smoothly into the groove/feeder without snagging. |
Essential Hardware
Section titled “Essential Hardware”| Component | Function |
|---|---|
| Pre-Feeder | A device mounted below the mast gate to guide the bolt rope into the groove prevents jamming. |
| Tensioning System | Cunningham control is critical as the rope is not fixed to the mast at intervals (unlike sliders). |
Applications:
- Racing: Maximizes aerodynamic efficiency (seals the gap between mast and sail).
- Small Boats: Simple, lightweight, low windage.
- In-Mast Furling: Uses specialized thin bolt ropes to roll smoothly inside the mast.
5. Luff Hardware Specifications
Section titled “5. Luff Hardware Specifications”Complete technical reference for Bainbridge, Selden, Rutgerson, Ronstan, and Viadana luff systems.
System Mechanics & Materials
Section titled “System Mechanics & Materials”- Mechanics: Sliders must handle Compression (wind load), Tension (halyard load), and Shear (side load).
- Friction: $\mu$ is minimized using PTFE-impregnated Nylon 66 or Hard-Anodized Aluminum.
- Materials:
- Nylon 66: Standard, self-lubricating, UV stabilized (Whitened or Black).
- 316 Stainless Steel: Essential for external tracks or high-load points, electro-polished to prevent corrosion.
- Hard-Anodized Al: Lightweight with PTFE intrusion for race boats.
1. Bainbridge International
Section titled “1. Bainbridge International”A-Series: Standard Nylon Sliders
Section titled “A-Series: Standard Nylon Sliders”High-strength Nylon 66, UV-stabilized.
| Model | Type | Width (mm) | Waist (mm) | Length (mm) | Application |
|---|---|---|---|---|---|
| A007 | Flat | 15.5 | 6.5 | 30 | Standard internal |
| A008 | Flat | 18.0 | 9.0 | 33 | Standard internal |
| A009 | Flat | 22.2 | 11.0 | 35 | Standard internal |
| A013 | Semi-Round | 11.0 | 3.0 | 24 | Selden 511-601 compatible |
| A014 | Semi-Round | 14.0 | 4.0 | 30 | Selden 511-602 compatible |
| A015 | Semi-Round | 15.0 | 4.0 | 40 | Selden 511-603 compatible |
| A016 | Round | 7.5 | 3.0 | 27 | Small groove |
| A017 | Round | 9.0 | 3.0 | 27 | Medium groove |
| A018 | Round | 12.0 | 3.0 | 27 | Large groove |
| A107 | Flat | 15.2 | 7.5 | 45 | Low Friction Allslip |
| A108 | Flat | 19.0 | 9.0 | 45 | Low Friction Allslip |
B-Series: Heavy Duty & External
Section titled “B-Series: Heavy Duty & External”316 Stainless Steel or Aluminum + PTFE.
| Model | Material | Type | Size | Notes |
|---|---|---|---|---|
| B014SS | 316 SS | External | 15mm Track | Electro-polished |
| B015SS | 316 SS | External | 22mm Track | Electro-polished |
| B016SS | 316 SS | External | 25mm Track | Electro-polished |
| Q110 | Bronze | External | 22.2mm (7/8”) | Classic Bronze Track |
| B102 | Al + PTFE | Round | 11.0mm | Hardcoat Anodized |
| B307 | SS + PTFE | Flat | 15.8mm | Heavy Duty Flat |
2. Seldén Mast (511 Series)
Section titled “2. Seldén Mast (511 Series)”Industry standard for Seldén masts. Fracture load rated.
| Model | Masts | Width (mm) | Waist (mm) | Break Load | Material |
|---|---|---|---|---|---|
| 511-601 | E-Section | 11.0 | 4.0 | 700 N | White Nylon |
| 511-602 | E-Section | 14.0 | 5.0 | 2,250 N | White Nylon |
| 511-605 | C-Section | 20.0 | 8.5 (Oval) | 2,250 N | Black Nylon |
| 511-607 | C-Section | 20.0 | 8.5 (Oval) | 4,000 N | Heavily Reinforced |
3. Rutgerson Marin
Section titled “3. Rutgerson Marin”Feature “Pressure Absorbing” technology for full-batten loads.
| Model | Type | Width (mm) | Feature | Application |
|---|---|---|---|---|
| 2241-1030 | Semi-Round | 19.5 | Shock Absorbing | Selden C-Section Alternate |
| 2241-335 | Semi-Round | 14.0 | Low Friction | Selden E-Section Alternate |
| 1525-11 | Wheeled | 11.0 | 15.5mm Roller | Batten Car (Webbing fit) |
| 1526-23 | Wheeled | 23.0 | 19.5mm Roller | Batten Car (Webbing fit) |
4. Ronstan (PNP) & Viadana
Section titled “4. Ronstan (PNP) & Viadana”Specialized self-lubricating options.
| Brand | Model | Type | Desc |
|---|---|---|---|
| Ronstan | PNP18T | Round | 9.8mm Lubricated Nylon |
| Ronstan | PNP27T | Flat | 15.2mm Lubricated Nylon |
| Viadana | 23.10 | Cylindrical | 316 SS Adjustable Eye |
| Viadana | 23.21 | Flat | Al + PTFE for 25mm Track |