The last line of defense in heavy weather. A storm jib is a small, heavily built headsail designed to keep the boat moving and under control in severe conditions.
- Survival sailing: Maintain steerage and forward motion in 35+ knot winds
- Regulatory compliance: Required by ISAF/World Sailing Category 1-3 offshore racing rules
- Crew safety: Replaces deeply furled genoa, which loses shape and creates excessive heel
When to use: Once true wind exceeds 30-35 knots sustained, or when the furled genoa can no longer hold usable shape. See Headsail Reefing Best Practices for the transition decision.
| Parameter | Specification | Notes |
|---|
| Area | ~5% of foretriangle (I×J) | Regulatory maximum for ISAF/ORC |
| Luff Length | ~65% of I | Limited by hank/attachment height |
| LP (Luff Perpendicular) | 65-85% of J | Non-overlapping by design |
| Clew Height | High cut (min. 1.2m above deck) | Must clear bow waves and spray |
| Head Angle | 5-8° (narrow head) | Flat profile, minimal twist |
| Boat LOA | Storm Jib Area (approx) | Luff (approx) | LP (approx) |
|---|
| 30ft (9m) | 4-6 m² | 6.5m | 2.5m |
| 36ft (11m) | 6-8 m² | 7.5m | 3.0m |
| 42ft (13m) | 8-11 m² | 8.5m | 3.5m |
| 50ft (15m) | 11-15 m² | 10.0m | 4.0m |
| Material | Weight | Application |
|---|
| Heavy Dacron | 8-10 oz/yd² (270-340 gsm) | Standard — proven durability, easy repair |
| XRP Laminate + Double Taffeta | 190-220 gsm base | Performance — lighter, better shape holding |
| Spectra/Dyneema Laminate | 200-260 gsm | Racing — strongest strength-to-weight ratio |
Recommendation for most customers: Heavy Dacron (8 oz for boats under 40ft, 10 oz for 40ft+). The storm jib’s job is to survive, not perform — choose proven reliability over marginal weight savings.
- Seam thread: V-138 or V-207 polyester (double the standard thread size)
- UV stitching: PTFE/Tenara thread on all exposed seams
| Feature | Specification |
|---|
| Seam construction | Triple-stitched, zigzag + straight |
| Corner reinforcement | 4-6 layers radial patches, 300-400mm diameter |
| Panel layout | Cross-cut or tri-radial (both acceptable at this size) |
| Leech line | Internal, 3mm pre-stretched polyester |
| Telltales | 2 pairs minimum (hank-on visibility is limited) |
| Corner | Fitting | Specification |
|---|
| Head | Pressed ring (#4-#5) or webbing loop | Must accept halyard snap shackle |
| Tack | Heavy-duty D-ring or O-ring (#5-#6) | Webbing anchor, load-rated to forestay loads |
| Clew | Pressed ring (#5-#6) + webbing reinforcement | Must handle dynamic sheet loads in gusting conditions |
For ring specifications, see Corner Fittings & Rings.
| Method | Description | Best For |
|---|
| Piston hanks | Bronze or stainless piston snaps, 250-350mm spacing | Standard — reliable, independent of furler |
| Inner forestay | Dedicated inner stay with hanks or mini-furler | Offshore boats with cutter rig |
| Removable forestay | Dedicated storm stay, set up when needed | Racing boats without inner forestay |
Critical: Storm jibs should NOT rely on the roller furler. If the furler jams in heavy weather, you lose your ability to set headsails. The storm jib should have an independent attachment system.
| Requirement | Specification |
|---|
| ISAF/World Sailing | High-visibility orange panels required |
| Standard | International Orange (Pantone 172C or 1655C) |
| Panel coverage | Minimum 2 panels visible from both sides |
| Sail number | Optional but recommended (required in some classes) |
| Rule | Requirement |
|---|
| World Sailing OSR 4.26 | Storm jib must be capable of being set independently of forestay |
| ISAF Cat 1-3 | Storm jib required, <5% foretriangle area |
| IRC Rule | Storm jib included in sail inventory declaration |
| ORC | Measured as part of sail wardrobe |
- Storage: Pre-packed in dedicated bag with hanks pre-attached
- Location: Easily accessible from cockpit or companionway — NOT buried in forepeak
- Practice: Crew should practice deployment at least once per season in moderate conditions
- Pre-rigging: Consider pre-attaching halyard and sheets before heavy weather arrival